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Picoliter H-1 NMR Spectroscopy
Minard, Kevin R.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Wind, Robert A.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)
A RF probe that fits inside the bore of a small gradient coil package is described for routine 1H-NMR microscopy measurements on small samples. The probe operates at 500 MHz and houses a 267-um-diameter solenoid transceiver. When used in three dimensional chemical shift imaging (3D-CSI) experiments, the measured signal-to-noise ratio (SNR) is shown to be within 20-30 percent of theoretical limits formulated by only considering the solenoid's resistive losses. This is illustrated using a 100-um-diameter globule of triacylglycerols ({approx}900mM) that may be an oocyte precursor in young Xenopus Laevis frogs, and water sample containing choline at a concentration often found in live cells ({approx}33mM). In chemical shift images generated using a few thousand scans, the choline methyl line is found to have an acceptable SNR in resolved from just 5 picoliters in the Xenopus globule. It is concluded that the probe's sensitivity is sufficient for performing 1H-NMR on picoliter-scale volumes in biological cells and tissues.
Dynamic High-Resolution H-1 and P-31 NMR Spectroscopy and H-1 T-2 Measurements in Postmortem Rabbit Muscles Using Slow Magic Angle Spinning
Bertram, Hanne Christine; Hu, Jian Zhi; Rommereim, Donald N.; Wind, Robert A.; Andersen, Henrik J.
Postmortem changes in rabbit muscle tissue with different glycogen status (normal vs low) were followed continuously from 13 min postmortem until 8 h postmortem and again 20 h postmortem using simultaneous magic angle spinning 1H and 31P NMR spectroscopy together with measurement of the transverse relaxation time, T2, of the muscle water. The 1H metabolite spectra were measured using the phase-altered spinning sidebands (PASS) technique at a spinning rate of 40 Hz. pH values calculated from the 31P NMR spectra using the chemical shifts of the C-6 line of histidine in the 1H spectra and the chemical shifts of inorganic phosphate in the 31P spectra confirmed the different muscle glycogen status in the tissues. High-resolution 1H spectra obtained from the PASS technique revealed the presence of a new resonance line at 6.8 ppm during the postmortem period, which were absent in muscles with low muscle glycogen content. This new resonance line may originate from the aminoprotons in creatine, and its appearance may be a result of a pH effect on the exchange rate between the amino and the water protons and thereby the NMR visibility. Alternatively, the new resonance line may originate from the aromatic protons in tyrosine, and its appearance may be a result of a pH-induced protein unfolding exposing hydrophobic amino acid residues to the aqueous environment. Further studies are needed to evaluate these hypotheses. Finally, distributed analysis of the water T2 relaxation data revealed three relaxation populations and an increase in the population believed to reflect extramyofibrillar water through the postmortem period. This increase was significantly reduced (p < 0.0001) in samples from animals with low muscle glycogen content, indicating that the pH is controlling the extent of postmortem expulsion of water from myofibrillar structures. The significance of the postmortem increase in the amount extramyofibrillar water on the water-holding capacity was verified by centrifugation, which showed a reduced centrifugation loss in muscles with low preslaughter glycogen status (0.9 vs 1.9%, p 0.07).
Two dimensional NMR spectroscopy
Schram, J.; Bellama, J.M.
Two dimensional NMR represents a significant achievement in the continuing effort to increase solution in NMR spectroscopy. This book explains the fundamentals of this new technique and its analytical applications. It presents the necessary information, in pictorial form, for reading the ''2D NMR,'' and enables the practicing chemist to solve problems and run experiments on a commercial spectrometer by using the software provided by the manufacturer.
Sch³ler, Axel
is investigated. 5. Methodological development of selective NMR pulse sequences for the application in bioorganic. Bioorganic & Medicinal Chemistry Volume 19, Issue 11 (2011), 3497Ł3501. PROTEINENGINEERINGANDBIOANALYTICS
Introduction to NMR Spectroscopy and Physics. C-13 NMR in more detail than "Summary" 83 Chem 355 Jasperse C-13 NMR
Jasperse, Craig P.
-active nuclei: H-1, C-13, N-15, F-19, P-31, Si-29, Se-79, Sn-119 Some NMR-inactive nuclei: C-12, N-14, O-16Introduction to NMR Spectroscopy and Physics. C-13 NMR in more detail than "Summary" 83 Chem 355 Jasperse C-13 NMR I. Introduction to Spectroscopy Spectroscopy involves gaining information from
Extended hopane derivatives in sediments - Identification by H-1 NMR
NASA Technical Reports Server (NTRS)
Taylor, J.; Wardroper, A. M. K.; Maxwell, J. R.
Sedimentary C32 hopanoic acid, one of the most abundant in nature and of probable bacterial origin, has been isolated for the first time as a single component and characterized by H-1 NMR. The 17 alpha H, 21 beta H configuration of the C31 alkane has been similarly confirmed.
Gerhard Wider: Technical aspects of NMR spectroscopy with biological macromolecules .... Technical aspects of NMR spectroscopy
Wider, Gerhard
Gerhard Wider: Technical aspects of NMR spectroscopy with biological macromolecules .... -1- Technical aspects of NMR spectroscopy with biological macromolecules and studies of hydration in solution aspects of NMR spectroscopy with biological macromolecules .... -2- Contents 1. Introduction 5 2. Basic
Understanding NMR Spectroscopy
NSDL National Science Digital Library
Keeler, James
This site provides links to a series of PDF files that represent chapters of an e-text on the basics of NMR. While many other textbooks on NMR are available, the chief merit of this one is that it has a nice chapter on the NMR instrumentation (ch. 5) which should be accessible to undergraduates. The text also provides a relatively mathematics-free or maybe more accurately Dirac bracket notation-free introduction to 1-D and 2-D (COSY and NOESY) experiments that would be appreciated by advanced undergraduates or beginning graduate students involved in undergraduate research experiences using NMR.
NSDL National Science Digital Library
Lord, J.R.
This web site begins with a simple quantum description of NMR and proceeds to introduce resonance absorption, relaxation, chemical shifts, and scalar couplings. This site will be useful for advanced undergraduate students needing a description of NMR that is more detailed than that given in most introductory Organic texts.
Modern NMR spectroscopy: a guide for chemists
Sanders, J.K.M.; Hunter, B.K.
The aim of the authors of Modern NMR Spectroscopy is to bridge the communication gap between the chemist and the spectroscopist. The approach is nonmathematical, descriptive, and pictorial. To illustrate the ideas introduced in the text, the authors provide original spectra obtained specially for this purpose. Examples include spectroscopy of protons, carbon, and less receptive nuclei of interest to inorganic chemists. The authors succeed in making high-resolution NMR spectroscopy comprehensible for the average student or chemist.
Scalable NMR spectroscopy with semiconductor chips
Ha, Dongwan; Paulsen, Jeffrey; Sun, Nan; Song, Yi-Qiao; Ham, Donhee
State-of-the-art NMR spectrometers using superconducting magnets have enabled, with their ultrafine spectral resolution, the determination of the structure of large molecules such as proteins, which is one of the most profound applications of modern NMR spectroscopy. Many chemical and biotechnological applications, however, involve only small-to-medium size molecules, for which the ultrafine resolution of the bulky, expensive, and high-maintenance NMR spectrometers is not required. For these applications, there is a critical need for portable, affordable, and low-maintenance NMR spectrometers to enable in-field, on-demand, or online applications (e.g., quality control, chemical reaction monitoring) and co-use of NMR with other analytical methods (e.g., chromatography, electrophoresis). As a critical step toward NMR spectrometer miniaturization, small permanent magnets with high field homogeneity have been developed. In contrast, NMR spectrometer electronics capable of modern multidimensional spectroscopy have thus far remained bulky. Complementing the magnet miniaturization, here we integrate the NMR spectrometer electronics into 4-mm2 silicon chips. Furthermore, we perform various multidimensional NMR spectroscopies by operating these spectrometer electronics chips together with a compact permanent magnet. This combination of the spectrometer-electronics-on-a-chip with a permanent magnet represents a useful step toward miniaturization of the overall NMR spectrometer into a portable platform. PMID:25092330
New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoaceticum metabolic profiles
Xue, Junfeng; Isern, Nancy G.; Ewing, R James; Liyu, Andrey V.; Sears, Jesse A.; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R.; Ahring, Birgitte K.; Majors, Paul D.
An in-situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch-growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution, high sensitivity NMR (HR-NMR) spectroscopy. In-situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at an NMR frequency of 500 MHz, and aliquots of the bioreactor contents were taken for 600 MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in-situ NMR bioreactor facilitated monitoring of the fermentation process in real time, enabling identification of intermediate and end-point metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with the HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.
Rapid 3D MAS NMR Spectroscopy at Critical Sensitivity
Matsuki, Yoh
Sensitive SIFTing: Multidimensional non-uniform sampling (NUS) NMR spectroscopy is extended to the severely sensitivity-limited regime typical of MAS NMR of biomacromolecules by the use of spectroscopy by the integration ...
New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.
Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D
An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts. PMID:24946863
H-1 NMR study of ternary ammonia-alkali metal-graphite intercalation compounds
NASA Technical Reports Server (NTRS)
Tsang, T.; Fronko, R. M.; Resing, H. A.; Qian, X. W.; Solin, S. A.
For the first-stage ternary ammonia-alkali metal-graphite intercalation compounds M(NH3)(x)C24(x of about 4, M = K, Rb, Cs), three sets of triplet H-1 NMR spectral lines have been observed at various temperatures and orientations due to the H-1 - H-1 and N-14 - H-1 dipolar interactions. The structures of these compounds have been inferred as mobile (liquid-like) intercalant layers of planar M(NH3)4 ions in between the carbon layers. For the intercalated ammonia molecules, the potential barrier is about 0.2 eV and the molecular geometry is very close to the free NH3 in gas phase.
Molecular Structure and Dynamics by NMR Spectroscopy
NSDL National Science Digital Library
Edison, Arthur S.
This site provides PowerPoint slides for a lecture for a graduate-level course in NMR spectroscopy. The slides include useful animations which help to demonstrate the concepts described. While the casual student may find it hard to follow everything on the slides without an accompanying lecture, the files should be very useful for advanced students or educators putting together similar courses.
Solid-state NMR studies of the prion protein H1 fragment.
Heller, J.; Kolbert, A. C.; Larsen, R.; Ernst, M.; Bekker, T.; Baldwin, M.; Prusiner, S. B.; Pines, A.; Wemmer, D. E.
Conformational changes in the prion protein (PrP) seem to be responsible for prion diseases. We have used conformation-dependent chemical-shift measurements and rotational-resonance distance measurements to analyze the conformation of solid-state peptides lacking long-range order, corresponding to a region of PrP designated H1. This region is predicted to undergo a transformation of secondary structure in generating the infectious form of the protein. Solid-state NMR spectra of specifically 13C-enriched samples of H1, residues 109-122 (MKHMAGAAAAGAVV) of Syrian hamster PrP, have been acquired under cross-polarization and magic-angle spinning conditions. Samples lyophilized from 50% acetonitrile/50% water show chemical shifts characteristic of a beta-sheet conformation in the region corresponding to residues 112-121, whereas samples lyophilized from hexafluoroisopropanol display shifts indicative of alpha-helical secondary structure in the region corresponding to residues 113-117. Complete conversion to the helical conformation was not observed and conversion from alpha-helix back to beta-sheet, as inferred from the solid-state NMR spectra, occurred when samples were exposed to water. Rotational-resonance experiments were performed on seven doubly 13C-labeled H1 samples dried from water. Measured distances suggest that the peptide is in an extended, possibly beta-strand, conformation. These results are consistent with the experimental observation that PrP can exist in different conformational states and with structural predictions based on biological data and theoretical modeling that suggest that H1 may play a key role in the conformational transition involved in the development of prion diseases. PMID:8844854
Effects and mechanisms of acetyl-L-cysteine in rats with chronic mountain sickness with H1-NMR metabolomics methods
Maimaitiyiming, Dilinuer; Aikemu, Ainiwaer; Kamilijiang, Mayila; Salamu, Adila; Zhang, Xiangyang
Background We established a rat model of chronic mountain sickness using acetyl-L-cysteine. Then we studied the effects and mechanisms of acetyl-L-cysteine (Da) in rats with chronic mountain sickness using nuclear magnetic resonance (H1-NMR) metabolomics methods. Material/Methods Using NMR spectroscopy combined with pattern recognition and orthogonal partial least squares discriminant analysis, we analyzed the impact of Da on blood metabolism in rats with chronic mountain sickness by determining different metabolites and changes in metabolic network in the blood of rats with mountain sickness after the intragastric administration of different doses of Da suspension. Results Increased levels of amino acids (valine, tyrosine, 1-methyl-histidine, leucine, phenylalanine, and methionine) were detected in the blood of rats in the chronic mountain sickness group, yet significantly decreased levels were detected in control rats. At the same time, ?-glucose and ?-glucose levels were markedly elevated in the blood of rats in the model group but decreased in the chronic mountain sickness group, which indicated a statistically significant difference compared with the chronic altitude sickness model group (P<0.05). Conclusions Da has a significant impact on the metabolism of rats with chronic mountain sickness. Da may act on the disturbed glucose metabolism and amino acid metabolism in rats triggered by chronic mountain sickness, resulting in the treatment and prevention of this disease. PMID:24816079
Access to NMR Spectroscopy for Two-Year College Students: The NMR Site at Trinity University
ERIC Educational Resources Information Center
Mills, Nancy S.; Shanklin, Michael
Students at two-year colleges and small four-year colleges have often obtained their exposure to NMR spectroscopy through "canned" spectra because the cost of an NMR spectrometer, particularly a high-field spectrometer, is prohibitive in these environments. This article describes the design of a NMR site at Trinity University in which spectralģ
Stacking structure of confined 1-butanol in SBA-15 investigated by solid-state NMR spectroscopy.
Lin, Yun-Chih; Chou, Hung-Lung; Sarma, Loka Subramanyam; Hwang, Bing-Joe
Understanding the complex thermodynamic behavior of confined amphiphilic molecules in biological or mesoporous hosts requires detailed knowledge of the stacking structures. Here, we present detailed solid-state NMR spectroscopic investigations on 1-butanol molecules confined in the hydrophilic mesoporous SBA-15 host. A range of NMR spectroscopic measurements comprising of (1)H spin-lattice (T(1)), spin-spin (T(2)) relaxation, (13)C cross-polarization (CP), and (1)H,(1)H two-dimensional nuclear Overhauser enhancement spectroscopy ((1)H,(1)H 2D NOESY) with the magic angle spinning (MAS) technique as well as static wide-line (2)H NMR spectra have been used to investigate the dynamics and to observe the stacking structure of confined 1-butanol in SBA-15. The results suggest that not only the molecular reorientation but also the exchange motions of confined molecules of 1-butanol are extremely restricted in the confined space of the SBA-15 pores. The dynamics of the confined molecules of 1-butanol imply that the (1)H,(1)H 2D NOESY should be an appropriate technique to observe the stacking structure of confined amphiphilc molecules. This study is the first to observe that a significant part of confined 1-butanol molecules are orientated as tilted bilayered structures on the surface of the host SBA-15 pores in a time-average state by solid-state NMR spectroscopy with the (1)H,(1)H 2D NOESY technique. PMID:19746482
Exploring RNA polymerase regulation by NMR spectroscopy.
Dr÷gem³ller, Johanna; Strau▀, Martin; Schweimer, Kristian; W÷hrl, Birgitta M; Knauer, Stefan H; R÷sch, Paul
RNA synthesis is a central process in all organisms, with RNA polymerase (RNAP) as the key enzyme. Multisubunit RNAPs are evolutionary related and are tightly regulated by a multitude of transcription factors. Although Escherichia coli RNAP has been studied extensively, only little information is available about its dynamics and transient interactions. This information, however, are crucial for the complete understanding of transcription regulation in atomic detail. To study RNAP by NMR spectroscopy we developed a highly efficient procedure for the assembly of active RNAP from separately expressed subunits that allows specific labeling of the individual constituents. We recorded [(1)H,(13)C] correlation spectra of isoleucine, leucine, and valine methyl groups of complete RNAP and the separately labeled ?' subunit within reconstituted RNAP. We further produced all RNAP subunits individually, established experiments to determine which RNAP subunit a certain regulator binds to, and identified the ? subunit to bind NusE. PMID:26043358
NMR Analysis of Unknowns: An Introduction to 2D NMR Spectroscopy
ERIC Educational Resources Information Center
Alonso, David E.; Warren, Steven E.
A study combined 1D (one-dimensional) and 2D (two-dimensional) NMR spectroscopy to solve structural organic problems of three unknowns, which include 2-, 3-, and 4-heptanone. Results showed [to the first power]H NMR and [to the thirteenth power]C NMR signal assignments for 2- and 3-heptanone were more challenging than for 4-heptanone owing to theģ
The Continuous Wavelet Transform, an Analysis Tool for NMR Spectroscopy
D. Barache; J. P. Antoine; J. M. Dereppe
The discrete wavelet transform has been used in NMR spectroscopy by several authors. We show here that the continuous wavelet transform (CWT) is also an efficient tool in that context. After reviewing briefly the analysis of spectral lines with the CWT, we discuss two applications specific to NMR, namely the removal of a large unwanted line and the rephasing of
Identification of natural epimeric flavanone glycosides by NMR spectroscopy
Federica Maltese; Cornelis Erkelens; Frank van der Kooy; Young Hae Choi; Robert Verpoorte
Recently advanced analytical technology has provided evidence of the existence of stereoisomers of many natural products. Particularly, flavanones which might have two different configurations at C-2 exist in many food additives, e.g., citrus fruits. In this study, the possible stereoisomers of flavanone glycosides were identified by NMR spectroscopy. Based on NMR spectra of common flavanone glycosides such as naringin, hesperidin,
ORIGINAL PAPER NMR spectroscopy as a screening tool to validate
Paris-Sud XI, Universitķ de
for the rapid routine analysis of milk and milk substitutes. (NMR) (400 MHz 1 H)"" (SIMCA)(, ), (PLS) Dairy intolerance . Milk . Milk substitutes . Soy milk . Dairy products . . . . . . 1 Introduction DueORIGINAL PAPER NMR spectroscopy as a screening tool to validate nutrition labeling of milk, lactose
Investigation of Zeolite Nucleation and Growth Using NMR SpectroscopyĀ
Rivas Cardona, Alejandra
and control of the zeolite properties. The primary objective of this dissertation is to determine the strength of organicinorganic interactions (i.e., the adsorption Gibbs energy) in transparent synthesis mixtures using PFG NMR spectroscopy, in order...
1H-detected 1H- 1H correlation spectroscopy of a stereo-array isotope labeled amino acid under fast magic-angle spinning
NASA Astrophysics Data System (ADS)
Takahashi, Hiroki; Kainosho, Masatsune; Akutsu, Hideo; Fujiwara, Toshimichi
The combined use of selective deuteration, stereo-array isotope labeling (SAIL), and fast magic-angle spinning effectively suppresses the 1H- 1H dipolar couplings in organic solids. This method provided the high-field 1H NMR linewidths comparable to those achieved by combined rotation and multiple-pulse spectroscopy. This technique was applied to two-dimensional 1H-detected 1H- 1H polarization transfer CHH experiments of valine. The signal sensitivity for the 1H-detected CHH experiments was greater than that for the 13C-detected 1H- 1H polarization transfer experiments by a factor of 2-4. We obtained the 1H- 1H distances in SAIL valine by CHH experiments with an accuracy of about 0.2 ┼ by using a theory developed for 1H- 1H polarization transfer in 13C-labeled organic compounds.
Fragment-Based Drug Discovery Using NMR Spectroscopy
Harner, Mary J.; Frank, Andreas O.; Fesik, Stephen W.
Nuclear magnetic resonance (NMR) spectroscopy has evolved into a powerful tool for fragment-based drug discovery over the last two decades. While NMR has been traditionally used to elucidate the three-dimensional structures and dynamics of biomacromolecules and their interactions, it can also be a very valuable tool for the reliable identification of small molecules that bind to proteins and for hit-to-lead optimization. Here, we describe the use of NMR spectroscopy as a method for fragment-based drug discovery and how to most effectively utilize this approach for discovering novel therapeutics based on our experience. PMID:23686385
FAST-NMR: Functional Annotation Screening Technology Using NMR Spectroscopy
Powers, Robert
.; Fellenberg, M.; Heumann, K.; Mewes, H.-W. Nucleic Acids Res. 2003, 31, 207. (4) Kanehisa, M.; Goto, S.; Kawashima, S.; Okuno, Y.; Hattori, M. Nucleic Acids Res. 2004, 32, D277. Figure 1. Functional information-ligand interactions are determined through a tiered NMR screen using a library composed of compounds with known
Proton-Detected Solid-State NMR Spectroscopy of Bone with Ultrafast Magic Angle Spinning
Mroue, Kamal H.; Nishiyama, Yusuke; Kumar Pandey, Manoj; Gong, Bo; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy
While obtaining high-resolution structural details from bone is highly important to better understand its mechanical strength and the effects of aging and disease on bone ultrastructure, it has been a major challenge to do so with existing biophysical techniques. Though solid-state NMR spectroscopy has the potential to reveal the structural details of bone, it suffers from poor spectral resolution and sensitivity. Nonetheless, recent developments in magic angle spinning (MAS) NMR technology have made it possible to spin solid samples up to 110?kHz frequency. With such remarkable capabilities, 1H-detected NMR experiments that have traditionally been challenging on rigid solids can now be implemented. Here, we report the first application of multidimensional 1H-detected NMR measurements on bone under ultrafast MAS conditions to provide atomistic-level elucidation of the complex heterogeneous structure of bone. Our investigations demonstrate that two-dimensional 1H/1H chemical shift correlation spectra for bone are obtainable using fp-RFDR (finite-pulse radio-frequency-driven dipolar recoupling) pulse sequence under ultrafast MAS. Our results infer that water exhibits distinct 1H?1H dipolar coupling networks with the backbone and side-chain regions in collagen. These results show the promising potential of proton-detected ultrafast MAS NMR for monitoring structural and dynamic changes caused by mechanical loading and disease in bone. PMID:26153138
Solid-State NMR Spectroscopy for the Physical Chemistry Laboratory
ERIC Educational Resources Information Center
Kinnun, Jacob J.; Leftin, Avigdor; Brown, Michael F.
Solid-state nuclear magnetic resonance (NMR) spectroscopy finds growing application to inorganic and organic materials, biological samples, polymers, proteins, and cellular membranes. However, this technique is often neither included in laboratory curricula nor typically covered in undergraduate courses. On the other hand, spectroscopy andģ
Protonproton Overhauser NMR spectroscopy with polypeptide chains in large structures
Wider, Gerhard
© rich, Switzerland; ¦Howard Hughes Medical Institute and Department of Genetics, Yale University School maromolecular assemblies in solution. 1HŁ1H NOE GroE chaperonine system NMR assignments protein structure connectivities for sequential assignment of the backbone 1 HN , 15 N, 13 C , and 13 CO resonances (1
Metabolism of human gliomas: Assessment with H-1 MR spectroscopy and F-18 fluorodeoxyglucose PET
Alger, J.R.; Frank, J.A.; Bizzi, A.; Fulham, M.J.; DeSouza, B.X.; Duhaney, M.O.; Inscoe, S.W.; Black, J.L.; van Zijl, P.C.; Moonen, C.T. (National Institute of Neurological Disorders and Stroke, National Institutes of Health (NIH), Bethesda, MD (USA))
Localized hydrogen-1 magnetic resonance (MR) spectroscopy and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) were employed to obtain metabolic information from intracranial gliomas. Advantages and difficulties associated with comparison of results from the two modalities were realized. Forty patients were studied with H-1 MR spectroscopy. MR signal intensities from lactate, N-acetylaspartate (NAA), choline, and creatine from a volume of interest containing the tumor and a contralateral volume were obtained and evaluated. NAA signal intensities were generally decreased in the tumor spectra, and choline signal intensities were elevated. H-1 MR spectroscopy was unsuccessful in eight patients, and FDG PET scans were not obtained in four of the patients with successful MR spectroscopic examinations. Lactate signal intensity was detected in 10 of the 28 patients who had successful H-1 MR spectroscopic and FDG PET studies. Lactate signal intensities were observed in lesions shown at FDG PET to be hypermetabolic, as well as in lesions found to be hypometabolic.
Nanoscale NMR spectroscopy and imaging of multiple nuclear species.
DeVience, Stephen J; Pham, Linh M; Lovchinsky, Igor; Sushkov, Alexander O; Bar-Gill, Nir; Belthangady, Chinmay; Casola, Francesco; Corbett, Madeleine; Zhang, Huiliang; Lukin, Mikhail; Park, Hongkun; Yacoby, Amir; Walsworth, Ronald L
Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple nuclear species in bulk matter, with wide-ranging applications from basic physics and chemistry to biomedical imaging. However, the spatial resolution of conventional NMR and MRI is limited to several micrometres even at large magnetic fields (>1?T), which is inadequate for many frontier scientific applications such as single-molecule NMR spectroscopy and in vivo MRI of individual biological cells. A promising approach for nanoscale NMR and MRI exploits optical measurements of nitrogen-vacancy (NV) colour centres in diamond, which provide a combination of magnetic field sensitivity and nanoscale spatial resolution unmatched by any existing technology, while operating under ambient conditions in a robust, solid-state system. Recently, single, shallow NV centres were used to demonstrate NMR of nanoscale ensembles of proton spins, consisting of a statistical polarization equivalent to ?100-1,000 spins in uniform samples covering the surface of a bulk diamond chip. Here, we realize nanoscale NMR spectroscopy and MRI of multiple nuclear species ((1)H, (19)F, (31)P) in non-uniform (spatially structured) samples under ambient conditions and at moderate magnetic fields (?20?mT) using two complementary sensor modalities. PMID:25559712
Nuclear magnetic resonance (NMR) spectroscopy has been utilized for assessing ecotoxicity in small fish models by means of metabolomics. Two fundamental challenges of NMR-based metabolomics are the detection limit and characterization of metabolites (or NMR resonance assignments...
Quantitative 2H NMR spectroscopy with 1H lock extender.
Vignali, Carlo; Caligiani, Augusta; Palla, Gerardo
An inexpensive external unit that allows the use of the commercial high-resolution NMR spectrometer for (2)H observation with an (1)H lock system is described. The external unit does not require any tuning, is extremely easy to use, and could be a cheaper and more straightforward alternative to the more expensive (19)F lock configuration. An application for the quantitative determination of the natural isotopic ratio (2)H/(1)H of ethanol and acetic acid is reported. PMID:17485230
'Shim pulses' for NMR spectroscopy in inhomogeneous magneticfields
Daniel Topgaard; Rachel W. Martin; Dimitris Sakellariou; Carlos Meriles; Alexander Pines
NMR spectroscopy conveys information about chemical structure through ppm-scale shifts of the resonance frequency depending on the chemical environment. In order to observe these small shifts, magnets with highly homogeneous magnetic field BŌ are used. The high cost and large size of these magnets are a consequence of the requirement for high homogeneity. In this contribution we introduce a new
Sandia National Laboratories is working with the EPA to evaluate and develop mathematical tools for analysis of the collected NMR spectroscopy data. Initially, we have focused on the use of Multivariate Curve Resolution (MCR) also known as molecular factor analysis (MFA), a tech...
Characterizing protein-glycosaminoglycan interactions using solution NMR spectroscopy.
Joseph, Prem Raj B; Poluri, Krishna Mohan; Sepuru, Krishna Mohan; Rajarathnam, Krishna
Solution nuclear magnetic resonance (NMR) spectroscopy and, in particular, chemical shift perturbation (CSP) titration experiments are ideally suited for characterizing the binding interface of macromolecular complexes. (1)H-(15)?N-HSQC-based CSP studies have become the method of choice due to their simplicity, short time requirements, and not requiring high-level NMR expertise. Nevertheless, CSP studies for characterizing protein-glycosaminoglycan (GAG) interactions have been challenging due to binding-induced aggregation/precipitation and/or poor quality data. In this chapter, we discuss how optimizing experimental variables such as protein concentration, GAG size, and sensitivity of NMR instrumentation can overcome these roadblocks to obtain meaningful structural insights into protein-GAG interactions. PMID:25325963
Optimal control in NMR spectroscopy: Numerical implementation in SIMPSON
NASA Astrophysics Data System (ADS)
ToÜner, Zden?k; Vosegaard, Thomas; Kehlet, Cindie; Khaneja, Navin; Glaser, Steffen J.; Nielsen, Niels Chr.
We present the implementation of optimal control into the open source simulation package SIMPSON for development and optimization of nuclear magnetic resonance experiments for a wide range of applications, including liquid- and solid-state NMR, magnetic resonance imaging, quantum computation, and combinations between NMR and other spectroscopies. Optimal control enables efficient optimization of NMR experiments in terms of amplitudes, phases, offsets etc. for hundreds-to-thousands of pulses to fully exploit the experimentally available high degree of freedom in pulse sequences to combat variations/limitations in experimental or spin system parameters or design experiments with specific properties typically not covered as easily by standard design procedures. This facilitates straightforward optimization of experiments under consideration of rf and static field inhomogeneities, limitations in available or desired rf field strengths (e.g., for reduction of sample heating), spread in resonance offsets or coupling parameters, variations in spin systems etc. to meet the actual experimental conditions as close as possible. The paper provides a brief account on the relevant theory and in particular the computational interface relevant for optimization of state-to-state transfer (on the density operator level) and the effective Hamiltonian on the level of propagators along with several representative examples within liquid- and solid-state NMR spectroscopy.
Structural Transitions in Short-Chain Lipid Assemblies Studied by P-NMR Spectroscopy
Kleinschmidt, J÷rg H.
Structural Transitions in Short-Chain Lipid Assemblies Studied by 31 P-NMR Spectroscopy Jo© rg HCnPG), and diacylphosphatidylserine (diCnPS) were investigated by 31 P nuclear magnetic resonance (NMR) spectroscopy as a function diacylphospholipid classes and the 31 P-NMR spectra provided evidence for a tubular network that appeared
Characterization of amorphous material in shocked quartz by NMR spectroscopy
Assink, R.A.; Boslough, M.B.; Cygan, R.T.
Nuclear magnetic resonance (NMR) analysis of the recovered products from a series of controlled explosive shock-loading experiments on quartz powders was performed to investigate shock-induced amorphization processes. Silicon-29 NMR spectroscopy is an excellent probe of the local bonding environment of silicon in minerals and is capable of detecting and characterizing amorphous and disordered components. NMR spectra obtained for the recovered material exhibit a narrow resonance associated with the shocked crystalline material, and a broad component consistent with an amorphous phase despite the absence of evidence for glass from optical microscopy. The NMR measurements were performed over a range of recycle times from 1 to 3 {times} 10{sup 5} S. Results demonstrate that the magnetization in both the crystalline and amorphous material following power-law behavior as a function of recycle time. The amorphous component dominates the spectra for short NMR recycle times due to its shorter relaxation time relative to the crystalline material. Fractal analysis of the power-law relations suggests a fractal dimension of 2 for the amorphous phase and 3 for the crystalline phase.
Measuring protein reduction potentials using 15N HSQC NMR spectroscopy.
Taylor, Samantha L; Crawley-Snowdon, Harriet; Wagstaff, Jane L; Rowe, Michelle L; Shepherd, Mark; Williamson, Richard A; Howard, Mark J
NMR spectroscopy was used to measure reduction potentials of four redox proteins by following multiple (15)N HSQC protein resonances across a titration series using mixtures of oxidised and reduced glutathione. Results for PDI a, PDI ab and DsbA agree with the literature and our result for ERp18 confirms this protein as an oxidoreductase of comparable or greater reducing strength than PDI a. PMID:23360928
Measuring protein reduction potentials using 15N HSQC NMR spectroscopyå
Taylor, Samantha L.; Crawley-Snowdon, Harriet; Wagstaff, Jane L.; Rowe, Michelle L.; Shepherd, Mark; Williamson, Richard A.; Howard, Mark J.
NMR spectroscopy was used to measure reduction potentials of four redox proteins by following multiple 15N HSQC protein resonances across a titration series using mixtures of oxidised and reduced glutathione. Results for PDI a, PDI ab and DsbA agree with the literature and our result for ERp18 confirms this protein as an oxidoreductase of comparable or greater reducing strength than PDI a. PMID:23360928
Optimization of THz Wave Coupling into Samples in DNP/NMR Spectroscopy
Barnes, Alexander
High power millimeter wave and terahertz sources are used in DNP/NMR spectroscopy to greatly enhance the NMR signal. A key issue is the efficient coupling of the source power to the sample. We present HFSS calculations ...
Proton-proton Overhauser NMR spectroscopy with polypeptide chains in large structures.
Horst, Reto; Wider, Gerhard; Fiaux, Jocelyne; Bertelsen, Eric B; Horwich, Arthur L; W³thrich, Kurt
The use of 1H-1H nuclear Overhauser effects (NOE) for structural studies of uniformly deuterated polypeptide chains in large structures is investigated by model calculations and NMR experiments. Detailed analysis of the evolution of the magnetization during 1H-1H NOE experiments under slow-motion conditions shows that the maximal 1H-1H NOE transfer is independent of the overall rotational correlation time, even in the presence of chemical exchange with the bulk water, provided that the mixing time is adjusted for the size of the structure studied. 1H-1H NOE buildup measurements were performed for the 472-kDa complex of the 72-kDa cochaperonin GroES with a 400-kDa single-ring variant of the chaperonin GroEL (SR1). These experiments demonstrate that multidimensional NOESY experiments with cross-correlated relaxation-enhanced polarization transfer and transverse relaxation-optimized spectroscopy elements can be applied to structures of molecular masses up to several hundred kilodaltabs, which opens new possibilities for studying functional interactions in large maromolecular assemblies in solution. PMID:17032756
Magnesium silicate dissolution investigated by S1-29 MAS, H-1 Si-29 CPMAS, Mg-25 QCPMG, and H-1 Mg-25 CP QCPMG NMR
Davis, M C [Oak Ridge National Laboratory (ORNL); Brouwer, Piet W [ORNL; Wesolowski, David J [ORNL; Anovitz, Lawrence {Larry} M [ORNL
Olivine-(Mg,Fe){sub 2}SiO{sub 4}-has been the subject of frequent investigation in the earth sciences because of its simple structure and rapid dissolution kinetics. Several studies have observed a preferential release of the divalent cation with respect to silicon during weathering under acidic conditions, which has been correlated to the formation of a silicon-rich leached layer. While leached layer formation has been inferred through the changing solution chemistry, a thorough spectroscopic investigation of olivine reacted under acidic conditions has not been conducted. The pure magnesium end member of the olivine series (forsterite-Mg2SiO4) was chosen for detailed investigations in this study because paramagnetic iron hinders NMR investigations by providing an extra mode of relaxation for neighboring nuclei, causing lineshapes to become significantly broadened and unobservable in the NMR spectrum. For reacting forsterite, spectroscopic interrogations using nuclear magnetic resonance (NMR) can elucidate the changing magnesium coordination and bonding environment. In this study, we combine analysis of the changing solution chemistry with advanced NMR techniques ({sup 29}Si MAS, {sup 1}H-{sup 29}Si CP MAS, {sup 25}Mg QCPMG, and {sup 1}H-{sup 25}Mg CP QCPMG NMR) to probe leached layer formation and secondary phase precipitation during the dissolution of forsterite at 150 C.
13C NMR spectroscopy applications to brain energy metabolism
Rodrigues, Tiago B.; Valette, Julien; Bouzier-Sore, Anne-Karine
13C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of 13C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the 13C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of 13C NMR data. Finally, new perspectives and applications offered by 13C hyperpolarization are described. PMID:24367329
Ultrafast two-dimensional NMR spectroscopy using constant acquisition gradients
NASA Astrophysics Data System (ADS)
Shrot, Yoav; Frydman, Lucio
Multidimensional NMR spectroscopy plays an important role in the characterization of molecular structure and dynamics. A new methodology for acquiring this kind of spectra has been recently demonstrated, endowed with the potential to compress arbitrary multidimensional NMR acquisitions into a single scan. This "ultrafast" nD acquisition protocol is based on a spatiotemporal encoding of the indirect-domain spin evolution, followed by a repetitive decoding and reencoding of the information thus stored employing a train of alternating-sign gradients. Such train of switching gradients extending throughout the course of the data acquisition may pose extreme demands on a magnetic resonance system, particularly when dealing with nonshielded gradients, strong eddy currents, or rapidly relaxing spin systems. Limits to the in vivo applicability of such fast-switching scheme may also arise due to gradient-induced perineural stimulation. The present study describes a new approach to ultrafast nD NMR that reduces the number of gradient switchings during the acquisition period to zero, leading in essence to a constant-gradient acquisition scheme. This approach operates on the basis of a novel spatiotemporal encoding including discrete, temporally overlapping, frequency-shifted pulses. Principles and examples of this new approach are given; sensitivity limitations and signal-enhancing prospects of such constant-gradient acquisitions are also discussed and exemplified.
Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain Investigations
Frydman, Lucio
Ultrafast 2D NMR Spectroscopy Using Sinusoidal Gradients: Principles and Ex Vivo Brain ultrafast acquisitions of 2D NMR spectra with suitable spectral widths on a microimaging probe (for both Wiley-Liss, Inc. Key words: ultrafast 2D NMR; magnetic resonance spectros- copy; brain metabolites; 2D
Solid-State Dipolar INADEQUATE NMR Spectroscopy with a Large Double-Quantum Spectral Width
Hong, Mei
Solid-State Dipolar INADEQUATE NMR Spectroscopy with a Large Double-Quantum Spectral Width Mei Hong Academic Press Key Words: solid-state NMR; INADEQUATE; double-quan- tum; C7; dipolar recoupling. Recently, solid-state homonuclear double-quantum NMR spec- troscopy has been increasingly employed to obtain
Structure of a Conserved Retroviral RNA Packaging Element by NMR Spectroscopy and Cryo-Electron Tomography
Miyazaki, Yasuyuki; Irobalieva, Rossitza N.; Tolbert, Blanton; Smalls-Mantey, Adjoa; Iyalla, Kilali; Loeliger, Kelsey; DÆSouza, Victoria; Khant, Htet; Schmid, Michael F.; Garcia, Eric; Telesnitsky, Alice; Chiu, Wah; Summers, Michael F.
The 5?-untranslated regions (5?-UTRs) of all gammaretroviruses contain a conserved ōdouble hairpin motifö (?CD) that is required for genome packaging. Both hairpins (SL-C and SL-D) contain GACG tetraloops that, in isolated RNAs, are capable of forming ōkissingö interactions stabilized by two intermolecular G-C base pairs. We have determined the three-dimensional structure of the double hairpin from the Moloney Murine Leukemia Virus (MoMuLV) ([?CD]2, 132-nucleotides, 42.8 kDaltons) using a 2H-edited NMR spectroscopy-based approach. This approach enabled the detection of 1H-1H dipolar interactions that were not observed in previous studies of isolated SL-C and SL-D hairpin RNAs using traditional 1H-1H correlated and 1H-13C-edited NMR methods. The hairpins participate in intermolecular cross-kissing interactions (SL-C to SL-DÆ and SLCÆ to SL-D), and stack in an end-to-end manner (SL-C to SL-D and SL-CÆ to SL-DÆ) that gives rise to an elongated overall shape (ca. 95 ┼ by 45 ┼ by 25 ┼). The global structure was confirmed by cryo-electron tomography (cryo-ET), making [?CD]2 simultaneously the smallest RNA to be structurally characterized to date by cryo-ET and among the largest to be determined by NMR. Our findings suggest that, in addition to promoting dimerization, [?CD]2 functions as a scaffold that helps initiate virus assembly by exposing a cluster of conserved UCUG elements for binding to the cognate nucleocapsid domains of assembling viral Gag proteins. PMID:20933521
Spin-Noise-Detected Two-Dimensional Fourier-Transform NMR Spectroscopy
We introduce two-dimensional NMR spectroscopy detected by recording and processing the noise originating from nuclei that have not been subjected to any radio frequency excitation. The method relies on cross-correlation of two noise blocks that bracket the evolution and mixing periods. While the sensitivity of the experiment is low in conventional NMR setups, spin-noise-detected NMR spectroscopy has great potential for use with extremely small numbers of spins, thereby opening a way to nanoscale multidimensional NMR spectroscopy. PMID:24294412
An Oil Spill in a Tube: An Accessible Approach for Teaching Environmental NMR Spectroscopy
ERIC Educational Resources Information Center
Simpson, Andre┤ J.; Mitchell, Perry J.; Masoom, Hussain; Mobarhan, Yalda Liaghati; Adamo, Antonio; Dicks, Andrew P.
NMR spectroscopy has great potential as an instrumental method for environmental chemistry research and monitoring but may be underused in teaching laboratories because of its complexity and the level of expertise required in operating the instrument and interpreting data. This laboratory experiment introduces environmental NMR spectroscopy toģ
NMR spectroscopy as a novel approach to the monitoring of renal transplant function
Peta J D Foxall; George J Mellotte; Michael R Bending; John C Lindon; Jeremy K Nicholson
NMR spectroscopy as a novel approach to the monitoring of renal transplant function. High field 1H NMR spectroscopy was used for the rapid multicomponent analysis of low molecular wt compounds in urine in order to investigate the patterns of metabolic changes associated with early renal allograft dysfunction. Urine samples were collected daily for 14 days from 33 patients who underwent
Dynamics-based selective 2D (1)H/(1)H chemical shift correlation spectroscopy under ultrafast MAS conditions.
Zhang, Rongchun; Ramamoorthy, Ayyalusamy
Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90░ RF pulses) to selectively measure the correlation of (1)H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90░ pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of (1)H/(1)H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials. PMID:26026440
Dynamics-based selective 2D 1H/1H chemical shift correlation spectroscopy under ultrafast MAS conditions
NASA Astrophysics Data System (ADS)
Zhang, Rongchun; Ramamoorthy, Ayyalusamy
Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90░ RF pulses) to selectively measure the correlation of 1H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90░ pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of 1H/1H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials.
H1 -NMR spin-echo measurements of the spin dynamic properties in ?-(BETS)2FeCl4
NASA Astrophysics Data System (ADS)
Wu, Guoqing; Ranin, P.; Gaidos, G.; Clark, W. G.; Brown, S. E.; Balicas, L.; Montgomery, L. K.
H1 -NMR spin-echo measurements of the spin-echo decay M(2?) with a decay rate 1/T2 under applied magnetic field B0=9T along the a axis over the temperature (T) range of 2.0-180K are reported for a single crystal of the organic conductor ?-(BETS)2FeCl4 . It provides the spin dynamic properties in the paramagnetic metal (PM) and antiferromagnetic insulator (AFI) states as well as across the PM-AFI phase transition. A large slow beat structure in the spin-echo decay is observed with a typical beat frequency of fBś7kHz that varies across the spectrum. Its origin is attributed to the interactions between protons that are very strongly detuned by the large inhomogeneous field on a microscopic distance scale that is generated by the Fe3+ moments (spin Sd=5/2 ). A simple phenomenological model provides an excellent fit to the data. The values of 1/T2 in the PM phase are consistent with a T -independent contribution from the proton-proton dipole interaction plus the proton spin-lattice relaxation rate (1/T1) [W. G. Clark , Appl. Magn. Reson. 27, 279 (2004)], which has a significant contribution only above ś20K . At the PM-AFI transition (3.5K) , there is a discontinuous drop in 1/T2 by ś34% , indicating that the transition is first order, consistent with prior reports. Two possible main contributions to this drop are discussed. They are based upon the change in the local magnetic field caused by the change in the orientation of the Fe3+ moments at the transition.
Multiplicative or t1 Noise in NMR Spectroscopy
Granwehr, Josef
The signal in an NMR experiment is highly sensitive to fluctuations of the environment of the sample. If, for example, the static magnetic field B{sub 0}, the amplitude and phase of radio frequency (rf) pulses, or the resonant frequency of the detection circuit are not perfectly stable and reproducible, the magnetic moment of the spins is altered and becomes a noisy quantity itself. This kind of noise not only depends on the presence of a signal, it is in fact proportional to it. Since all the spins at a particular location in a sample experience the same environment at any given time, this noise primarily affects the reproducibility of an experiment, which is mainly of importance in the indirect dimensions of a multidimensional experiment, when intense lines are suppressed with a phase cycle, or for difference spectroscopy techniques. Equivalently, experiments which are known to be problematic with regard to their reproducibility, like flow experiments or experiments with a mobile target, tend to be affected stronger by multiplicative noise. In this article it is demonstrated how multiplicative noise can be identified and characterized using very simple, repetitive experiments. An error estimation approach is developed to give an intuitive, yet quantitative understanding of its properties. The consequences for multidimensional NMR experiments are outlined, implications for data analysis are shown, and strategies for the optimization of experiments are summarized.
Limits of detection of polydimethylsiloxane in (29)Si NMR spectroscopy.
Semchyschyn, D J; Macdonald, P M
Limits of detection for neat poly(dimethylsiloxane) (PDMS), as detected via (29)Si NMR spectroscopy, were determined by the IUPAC, graphical, and propagation of errors methods from calibration curves obtained using a 7.05 Tesla superconducting magnet equipped with a magic angle spinning (MAS) NMR probe. Under conditions permitting full relaxation of the nuclear spins (recycle time >150 sec), the limit of detection with 128 transients was 1.7, 2.2, and 3.7 mg PDMS (23, 30, and 50 micromoles elemental Si) for the IUPAC, graphical, and propagation of errors methods, respectively. A higher limit of detection results when additional sources of uncertainty are considered. From the strict dependence of the limit of detection on the inverse of the square root of the number of transients signal-averaged, it is possible to extrapolate to a limit of detection of 183 microg PDMS (2.47 micromoles elemental Si) for a 24-hr signal averaging period. This limit of detection is 3 orders of magnitude higher than silicon levels found in human blood. PMID:10748438
NMR planar micro coils for micro spectroscopy: design and characterisation.
Baxan, N; Rengle, A; ChŌteaux, J-F; Briguet, A; Pasquet, G; Morin, P; Fakri-Bouchet, L
The goal of this study is to determine the concentration sensitivity and the limit of detection of a SNMR receiver planar micro coil with ellipsoidal geometry 1000x500 microm, fabricated using an electroplating technique and used as SNMR receiver coil at 200 MHz. The maximum signal intensity on the NMR images and simulation of RF field distribution allows defining an active volume of 0.8 microL. The localised spectroscopy based on a PRESS sequence shows that the concentration sensitivity is closed to S(C)=2.33 M(-1) and the limit of detection LOD=0.8 M. This micro-system offers the possibility of new investigation techniques based on implantable micro coils used for in vivo study of local cerebral metabolites occupying a small volume (microL to nL order). PMID:17945835
Ceramic cells for high pressure NMR spectroscopy of proteins
NASA Astrophysics Data System (ADS)
Erlach, Markus Beck; Munte, Claudia E.; Kremer, Werner; Hartl, Rainer; Rochelt, D÷rte; Niesner, Dieter; Kalbitzer, Hans Robert
Application of high pressure to biological macromolecules can be used to find new structural states with a smaller specific volume of the system. High pressure NMR spectroscopy is a most promising analytical tool for the study of these states at atomic resolution. High pressure quartz cells are difficult to handle, high quality sapphire high pressure cells are difficult to obtain commercially. In this work, we describe the use of high pressure ceramic cells produced from yttrium stabilized ZrO 2 that are capable of resisting pressures up to 200 MPa. Since the new cells should also be usable in the easily damageable cryoprobes a completely new autoclave for these cells has been constructed, including an improved method for pressure transmission, an integrated safety jacket, a displacement body, and a fast self-closing emergency valve.
Detection of Taurine in Biological Tissues by 33S NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Musio, Roberta; Sciacovelli, Oronzo
The potential of 33S NMR spectroscopy for biochemical investigations on taurine (2-aminoethanesulfonic acid) is explored. It is demonstrated that 33S NMR spectroscopy allows the selective and unequivocal identification of taurine in biological samples. 33S NMR spectra of homogenated and intact tissues are reported for the first time, together with the spectrum of a living mollusc. Emphasis is placed on the importance of choosing appropriate signal processing methods to improve the quality of the 33S NMR spectra of biological tissues.
Multichannel visible spectroscopy diagnostic for particle transport studies in the H-1 heliac
NASA Astrophysics Data System (ADS)
Punzmann, H.; Shats, M. G.; Solomon, W. M.; Xia, H.
A multichannel spectroscopy diagnostic has been developed to study cross-field particle transport in the radiation-dominated low-temperature plasmas (Te<100 eV) in the H-1 heliac. The optical setup covers the full plasma minor radius in the poloidal plane collecting light from ten parallel chords arranged tangentially to the flux surfaces. The light collected from the plasma is coupled into optical fibers and through interference filters into photomultipliers. Two such ten-fiber arrays are aligned parallel to one another to allow the simultaneous monitoring of two different spectral lines. The net radial electron particle flux is determined from the continuity equation by integrating over the ionization source term in the steady-state partially ionized plasma. The diagnostic measures the neutral line intensities and their ratios (in case of helium using the line ratio technique) and also measures excited neutral and ion spectral lines (in case of the argon plasma transport studies). A comparative analysis of the radial particle transport in the low- and high-confinement regimes is presented.
Dynamic nuclear polarization enhanced NMR spectroscopy for pharmaceutical formulations.
Rossini, Aaron J; Widdifield, Cory M; Zagdoun, Alexandre; Lelli, Moreno; Schwarzwõlder, Martin; Copķret, Christophe; Lesage, Anne; Emsley, Lyndon
Dynamic nuclear polarization (DNP) enhanced solid-state NMR spectroscopy at 9.4 T is demonstrated for the detailed atomic-level characterization of commercial pharmaceutical formulations. To enable DNP experiments without major modifications of the formulations, the gently ground tablets are impregnated with solutions of biradical polarizing agents. The organic liquid used for impregnation (here 1,1,2,2-tetrachloroethane) is chosen so that the active pharmaceutical ingredient (API) is minimally perturbed. DNP enhancements (?) of between 40 and 90 at 105 K were obtained for the microparticulate API within four different commercial formulations of the over-the-counter antihistamine drug cetirizine dihydrochloride. The different formulations contain between 4.8 and 8.7 wt % API. DNP enables the rapid acquisition with natural isotopic abundances of one- and two-dimensional (13)C and (15)N solid-state NMR spectra of the formulations while preserving the microstructure of the API particles. Here this allowed immediate identification of the amorphous form of the API in the tablet. API-excipient interactions were observed in high-sensitivity (1)H-(15)N correlation spectra, revealing direct contacts between povidone and the API. The API domain sizes within the formulations were determined by measuring the variation of ? as a function of the polarization time and numerically modeling nuclear spin diffusion. Here we measure an API particle radius of 0.3 ?m with a single particle model, while modeling with a Weibull distribution of particle sizes suggests most particles possess radii of around 0.07 ?m. PMID:24410528
Improving the resolution in proton-detected through-space heteronuclear multiple quantum correlation NMR spectroscopy
NASA Astrophysics Data System (ADS)
Shen, Ming; Trķbosc, J.; Lafon, O.; Pourpoint, F.; Hu, Bingwen; Chen, Qun; Amoureux, J.-P.
Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong 1H-1H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t1 evolution period of dipolar-mediated HMQC (D-HMQC) experiment. We demonstrate that 1H-1H dipolar decoupling sequences during t1, such as symmetry-based schemes, phase-modulated Lee-Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave 1H irradiation. We also report that high resolution requires the preservation of 1H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D-HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t1 period. Moreover, we show that 1H-1H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t1-noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D 1H-{13C} D-HMQC experiments on [U-13C]-L-histidine?HCl?H2O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t1 period enable the detection of heteronuclear correlation between aliphatic protons and ammonium 14N sites in L-histidine?HCl?H2O.
Applications of Diffusion Ordered Spectroscopy (DOSY-NMR)
Technology Transfer Automated Retrieval System (TEKTRAN)
Diffusion-ordered NMR (DOSY-NMR) is a powerful, but under-utilized, technique for the investigation of mixtures based on translational diffusion rates. DOSY spectra allow for determination by NMR of components that may differ in molecular weight, geometry or complexation. Typical applications coul...
Development of a micro flow-through cell for high field NMR spectroscopy.
Alam, Todd Michael; McIntyre, Sarah K.
A highly transportable micro flow-through detection cell for nuclear magnetic resonance (NMR) spectroscopy has been designed, fabricated and tested. This flow-through cell allows for the direct coupling between liquid chromatography (LC) and gel permeation chromatography (GPC) resulting in the possibility of hyphenated LC-NMR and GPC-NMR. The advantage of the present flow cell design is that it is independent and unconnected to the detection probe electronics, is compatible with existing commercial high resolution NMR probes, and as such can be easily implemented at any NMR facility. Two different volumes were fabricated corresponding to between {approx}3.8 and 10 {micro}L detection volume. Examples of the performance of the cell on different NMR instruments, and using different NMR detection probes were demonstrated.
Parallel Atomic Force Microscopy and NMR Spectroscopy To Investigate Self-Assembled Protein-Nucleotide Aggregates
Dellaire, Graham
collagen monomer contains no phosphorus, unlike the triphosphate group of the ATP, thus making 31 P NMR spectroscopy a highly specific probe for the location and interaction of ATP. The changes in the 31 P NMR is found to correlate with decreased mobility of all three 31 P nuclei of ATP, as evinced by appreciable
Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings
Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R
A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.
Molecular areas of phospholipids as determined by 2H NMR spectroscopy
Brown, Michael F.
structures and membrane protein function. We have used 2H NMR spectroscopy to compare the properties of 1; EDTA, ethylenediaminetetraacetic acid; egg PE, egg yolk phosphatidylethanolamine; 2H NMR, deuterium chromatog- raphy; Tm, main (gel to liquid-crystalline) phase transition tempera- ture; T,,d, reduced
Preparation of Uniformly Isotope-labeled DNA Oligonucleotides for NMR Spectroscopy*
Clore, G. Marius
Preparation of Uniformly Isotope-labeled DNA Oligonucleotides for NMR Spectroscopy* (Received for the large scale preparation of uni- formly isotope-labeled DNA for NMR studies have been developed grown with 15 N- and 13 C-enriched nutrients (7Ł11). Isotope labeling of DNA has been difficult and most
Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)
ERIC Educational Resources Information Center
Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.
Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical andģ
Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy
Debelouchina, Galia T.
Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that confer the extraordinary ...
Observation of 1H-13C and 1H-1H proximities in a paramagnetic solid by NMR at high magnetic field under ultra-fast MAS.
Li, Shenhui; Trķbosc, Julien; Lafon, Olivier; Zhou, Lei; Shen, Ming; Pourpoint, Frķdķrique; Amoureux, Jean-Paul; Deng, Feng
The assignment of NMR signals in paramagnetic solids is often challenging since: (i) the large paramagnetic shifts often mask the diamagnetic shifts specific to the local chemical environment, and (ii) the hyperfine interactions with unpaired electrons broaden the NMR spectra and decrease the coherence lifetime, thus reducing the efficiency of usual homo- and hetero-nuclear NMR correlation experiments. Here we show that the assignment of (1)H and (13)C signals in isotopically unmodified paramagnetic compounds with moderate hyperfine interactions can be facilitated by the use of two two-dimensional (2D) experiments: (i) (1)H-(13)C correlations with (1)H detection and (ii) (1)H-(1)H double-quantum?single-quantum correlations. These methods are experimentally demonstrated on isotopically unmodified copper (II) complex of l-alanine at high magnetic field (18.8 T) and ultra-fast Magic Angle Spinning (MAS) frequency of 62.5 kHz. Compared to (13)C detection, we show that (1)H detection leads to a 3-fold enhancement in sensitivity for (1)H-(13)C 2D correlation experiments. By combining (1)H-(13)C and (1)H-(1)H 2D correlation experiments with the analysis of (13)C longitudinal relaxation times, we have been able to assign the (1)H and (13)C signals of each l-alanine ligand. PMID:25557861
Coherence selection in double CP MAS NMR spectroscopy
NASA Astrophysics Data System (ADS)
Yang, Jen-Hsien; Chou, Fang-Chieh; Tzou, Der-Lii M.
Applications of double cross-polarization (CP) magic-angle spinning (MAS) NMR spectroscopy, via 1H/ 15N and then 15N/ 13C coherence transfers, for 13C coherence selection are demonstrated on a 15N/ 13C-labeled N-acetyl-glucosamine (GlcNAc) compound. The 15N/ 13C coherence transfer is very sensitive to the settings of the experimental parameters. To resolve explicitly these parameter dependences, we have systematically monitored the 13C{ 15N/ 1H} signal as a function of the rf field strength and the MAS frequency. The data reveal that the zero-quantum coherence transfer, with which the 13C effective rf field is larger than that of the 15N by the spinning frequency, would give better signal sensitivity. We demonstrate in one- and two-dimensional double CP experiments that spectral editing can be achieved by tailoring the experimental parameters, such as the rf field strengths and/or the MAS frequency.
Investigating gabapentin polymorphism using solid-state NMR spectroscopy.
Dempah, Kassibla E; Barich, Dewey H; Kaushal, Aditya M; Zong, Zhixin; Desai, Salil D; Suryanarayanan, Raj; Kirsch, Lee; Munson, Eric J
Solid-state NMR spectroscopy (SSNMR), coupled with powder X-ray diffraction (PXRD), was used to identify the physical forms of gabapentin in samples prepared by recrystallization, spray drying, dehydration, and milling. Four different crystalline forms of gabapentin were observed: form I, a monohydrate, form II, the most stable at ambient conditions, form III, produced by either recrystallization or milling, and an isomorphous desolvate produced from desolvating the monohydrate. As-received gabapentin (form II) was ball-milled for 45 min in both the presence and absence of hydroxypropylcellulose (HPC). The samples were then stored for 2 days at 50░C under 0% relative humidity and analyzed by 13C SSNMR and PXRD. High-performance liquid chromatography was run on the samples to determine the amount of degradation product formed before and after storage. The 1HT1 values measured for the sample varied from 130 s for the as-received unstressed material without HPC to 11 s for the material that had been ball-milled in the presence of HPC. Samples with longer 1HT1 values were substantially more stable than samples that had shorter T1 values. Samples milled with HPC had detectable form III crystals as well. These results suggest that SSNMR can be used to predict gabapentin stability in formulated products. PMID:23180225
Magnesium silicate dissolution investigated by Si-29 MAS, H-1-Si-29 CPMAS, Mg-25 QCPMG NMR.
Davis, M C [Oak Ridge National Laboratory (ORNL); Wesolowski, David J [ORNL
Olivine-(Mg,Fe){sub 2}SiO{sub 4}-has been the subject of frequent investigation in the earth sciences because of its simple structure and rapid dissolution kinetics. Several studies have observed a preferential release of the divalent cation with respect to silicon during weathering under acidic conditions, which has been correlated to the formation of a silicon-rich leached layer. While leached layer formation has been inferred through the changing solution chemistry, a thorough spectroscopic investigation of olivine reacted under acidic conditions has not been conducted. The pure magnesium end member of the olivine series (forsterite-Mg{sub 2}SiO{sub 4}) was chosen for detailed investigations in this study because paramagnetic iron hinders NMR investigations by providing an extra mode of relaxation for neighboring nuclei, causing lineshapes to become significantly broadened and unobservable in the NMR spectrum. For reacting forsterite, spectroscopic interrogations using nuclear magnetic resonance (NMR) can elucidate the changing magnesium coordination and bonding environment. In this study, we combine analysis of the changing solution chemistry with advanced NMR techniques ({sup 29}Si MAS, {sup 1}H-{sup 29}Si CP MAS, {sup 25}Mg QCPMG, and {sup 1}H-{sup 25}Mg CP QCPMG NMR) to probe leached layer formation and secondary phase precipitation during the dissolution of forsterite at 150 C.
Interaction between DNA and chromosomal proteins HMGB1 and H1 studied by IR/VCD spectroscopy
NASA Astrophysics Data System (ADS)
Polyanichko, Alexander; Chikhirzhina, Elena
Binary complexes of calf thymus DNA with calf thymus non-histone chromosomal protein HMGB1 and linker histone H1 were studied using FTIR/VCD spectroscopy. The spectroscopic data showed that the interaction of the protein HMGB1 and histone H1 with DNA resulted in formation of two different types of the macromolecular complexes. Histone H1 retained its native structure even at high concentrations and induced DNA condensation upon binding at the protein to DNA ratio r (w/w) in the complex r ? 0.3. HMGB1 demonstrated the ability to form soluble complexes at considerably higher protein to DNA ratios. The obtained data suggest that the HMGB1 also participated in the protein-protein interactions via its C-terminal domain.
Mobility and Diffusion-Ordered Two-Dimensional NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Morris, Kevin Freeman
Mobility and diffusion-ordered two-dimensional nuclear magnetic resonance spectroscopy experiments have been developed for the analysis of mixtures. In the mobility -ordered experiments, the full range of positive and negative electrophoretic mobilities is displayed in one dimension and chemical shifts are displayed in the other. A concentric cylindrical tube electrophoresis chamber was designed to reduce the effective pathlength for current and to provide unidirectional flow for ions of interest. Techniques based upon the reverse precession method were also implemented to recover the signs of the mobilities and improved resolution in the mobility dimension was obtained by replacing Fourier transformation of truncated data sets with a linear prediction analysis. In the diffusion-ordered two-dimensional NMR experiments, the conventional chemical shift spectrum is resolved in one dimension and spectra of diffusion rates or molecular radii are resolved in the other. Diffusion dependent pulsed field gradient NMR data sets were inverted by means of the computer programs SPLMOD or DISCRETE, when discrete diffusion coefficients were present, and CONTIN when continuous distributions were present. Since the inversion is ill -conditioned, it was necessary to introduce additional information to limit the range of the solutions. In addition to prior knowledge of the decay kernels and non-negativity of amplitudes and damping constants, a set of rejection criteria was constructed for the discrete analysis case that took into account physical limits on diffusion coefficients, experimentally accessible values, and variations in effective decay kernels resulting from instrumental non-linearities. Examples of analyses of simulated data and experimental data for mixtures are presented as well as two-dimensional spectra generated by CONTIN for polydisperse polymer samples. Also, resolution in the diffusion dimension was increased by performing experiments on hydrophobic molecules in the presence of surfactant micelles. Finally, the diffusion-ordered experiment was used to study the polymer induced breakdown of micelles consisting of cetyltrimethylammonium bromide and sodium salicylate. Addition of the polymer poly(vinyl methyl ether) resulted in an increase in the micelle diffusion coefficient and at high polymer concentrations and elevated temperatures the polymer and micelle were observed to diffuse at the same rate.
[Non-invasive analysis of proteins in living cells using NMR spectroscopy].
Tochio, Hidehito; Murayama, Shuhei; Inomata, Kohsuke; Morimoto, Daichi; Ohno, Ayako; Shirakawa, Masahiro
NMR spectroscopy enables structural analyses of proteins and has been widely used in the structural biology field in recent decades. NMR spectroscopy can be applied to proteins inside living cells, allowing characterization of their structures and dynamics in intracellular environments. The simplest "in-cell NMR" approach employs bacterial cells; in this approach, live Escherichia coli cells overexpressing a specific protein are subjected to NMR. The cells are grown in an NMR active isotope-enriched medium to ensure that the overexpressed proteins are labeled with the stable isotopes. Thus the obtained NMR spectra, which are derived from labeled proteins, contain atomic-level information about the structure and dynamics of the proteins. Recent progress enables us to work with higher eukaryotic cells such as HeLa and HEK293 cells, for which a number of techniques have been developed to achieve isotope labeling of the specific target protein. In this review, we describe successful use of electroporation for in-cell NMR. In addition, (19)F-NMR to characterize protein-ligand interactions in cells is presented. Because (19)F nuclei rarely exist in natural cells, when (19)F-labeled proteins are delivered into cells and (19)F-NMR signals are observed, one can safely ascertain that these signals originate from the delivered proteins and not other molecules. PMID:25759048
Phosphorus speciation in a eutrophic lake by │╣P NMR spectroscopy.
Read, Emily K; Ivancic, Monika; Hanson, Paul; Cade-Menun, Barbara J; McMahon, Katherine D
For eutrophic lakes, patterns of phosphorus (P) measured by standard methods are well documented but provide little information about the components comprising standard operational definitions. Dissolved P (DP) and particulate P (PP) represents important but rarely characterized nutrient pools. Samples from Lake Mendota, Wisconsin, USA were characterized using 31-phosphorus nuclear magnetic resonance spectroscopy ((31)P NMR) during the open water season of 2011 in this unmatched temporal study of aquatic P dynamics. A suite of organic and inorganic P forms was detected in both dissolved and particulate fractions: orthophosphate, orthophosphate monoesters, orthophosphate diesters, pyrophosphate, polyphosphate, and phosphonates. Through time, phytoplankton biomass, temperature, dissolved oxygen, and water clarity were correlated with changes in the relative proportion of P fractions. Particulate P can be used as a proxy for phytoplankton-bound P, and in this study, a high proportion of polyphosphate within particulate samples suggested P should not be a limiting factor for the dominant primary producers, cyanobacteria. Hypolimnetic particulate P samples were more variable in composition than surface samples, potentially due to varying production and transport of sinking particles. Surface dissolved samples contained less P than particulate samples, and were typically dominated by orthophosphate, but also contained monoester, diester, polyphosphate, pyrophosphate, and phosphonate. Hydrologic inflows to the lake contained more orthophosphate and orthophosphate monoesters than in-lake samples, indicating transformation of P from inflowing waters. This time series explores trends of a highly regulated nutrient in the context of other water quality metrics (chlorophyll, mixing regime, and clarity), and gives insight on the variability of the structure and occurrence of P-containing compounds in light of the phosphorus-limited paradigm. PMID:24956605
Functional groups identified by solid state 13C NMR spectroscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...
Fast Proton Exchange in Histidine: Measurement of Rate Constants through Indirect Detection by NMR Spectroscopy
Sehgal, Akansha Ashvani; Duma, Luminita; Bodenhausen, Geoffrey; Pelupessy, Philippe
Owing to its imidazole side chain, histidine participates in various processes such as enzyme catalysis, pH regulation, metal binding, and phosphorylation. The determination of exchange rates of labile protons for such a system is important for understanding its functions. However, these rates are too fast to be measured directly in an aqueous solution by using NMR spectroscopy. We have obtained the exchange rates of the NH3+ amino protons and the labile NH?2 and NH?1 protons of the imidazole ring by indirect detection through nitrogen-15 as a function of temperature (272?K
Quantitative Determination of Carthamin in Carthamus Red by 1H-NMR Spectroscopy.
Yoshida, Takamitsu; Terasaka, Kazuyoshi; Kato, Setsuko; Bai, Fan; Sugimoto, Naoki; Akiyama, Hiroshi; Yamazaki, Takeshi; Mizukami, Hajime
Carthamus Red is a food colorant prepared from the petals of Carthamus tinctorius (Asteraceae) whose major pigment is carthamin. Since an authentic carthamin standard is difficult to obtain commercially for the preparation of calibration curves in HPLC assays, we applied (1)H-NMR spectroscopy to the quantitative determination of carthamin in commercial preparations of Carthamus Red. Carthamus Red was repeatedly extracted in methanol and the extract was dissolved in pyridine-d(5) containing hexamethyldisilane (HMD) prior to (1)H-NMR spectroscopic analysis. The carthamin contents were calculated from the ratios of singlet signal intensities at approximately ?: 9.3 derived from H-16 of carthamin to those of the HMD signal at ?: 0. The integral ratios exhibited good repeatability among NMR spectroscopic analyses. Both the intra-day and inter-day assay variations had coefficients of variation of <5%. Based on the coefficient of absorption, the carthamin contents of commercial preparations determined by (1)H-NMR spectroscopy correlated well with those determined by colorimetry, although the latter were always approximately 1.3-fold higher than the former, irrespective of the Carthamus Red preparations. In conclusion, the quantitative (1)H-NMR spectroscopy used in the present study is simple and rapid, requiring no carthamin standard for calibration. After HMD concentration has been corrected using certified reference materials, the carthamin contents determined by (1)H-NMR spectroscopy are System of Units (SI)-traceable. PMID:24436958
NMR Stark Spectroscopy: New Methods to Calibrate NMR Sensitivity to Electric Fields
NASA Astrophysics Data System (ADS)
Tarasek, Matthew R.
The influence of electrostatics on NMR parameters is well accepted. Thus, NMR is a promising route to probe electrical features within molecules and materials. However, applications of NMR Stark effects (E-field induced changes in spin energy levels) have been elusive. I have developed new approaches to resolve NMR Stark effects from an applied E field. This calibrates nuclear probes whose spectral response might later be used to evaluate internal E fields that are critical to function, such as those due to local charge distributions or sample structure. I will present two novel experimental approaches for direct calibration of NMR quadrupolar Stark effects (QSEs). In the first, steady-state (few-second) excitation by an E field at twice the NMR frequency (2? 0) is used to saturate spin magnetization. The extent of saturation vs. E-field amplitude calibrates the QSE response rate, while measurements vs sample orientation determine tensorial character. The second method instead synchronizes short (few Ąs) pulses of the 2?0 E field with a multiple-pulse NMR sequence. This, ōPOWERö (Perturbations Observed With Enhanced Resolution) approach enables more accurate measure of small QSEs (i.e. few Hz spectral changes). A 2nd key advantage is the ability to define tensorial response without reorienting the sample, but instead varying the phase of the 2?0 field. I will describe these experiments and my home-built NMR ōStark probeö, employed on a conventional wide-bore solid-state NMR system. Results with GaAs demonstrate each method, while extensions to a wider array of molecular and material systems may now be possible using these methods.
Ultrafast high-resolution magic-angle-spinning NMR spectroscopy.
Andrķ, Marion; Piotto, Martial; Caldarelli, Stefano; Dumez, Jean-Nicolas
We demonstrate the acquisition of ultrafast 2D NMR spectra of semi-solid samples, with a high-resolution magic-angle-spinning setup. Using a recent double-quantum NMR pulse sequence in optimised synchronisation conditions, high-quality 2D spectra can be recorded for a sample under magic-angle spinning. An illustration is given with a semi-solid sample of banana pulp. PMID:25946235
Synthesis and characterization of polyphosphazene copolymers using phosphorus-31 NMR spectroscopy
Stewart, F.F.; Peterson, E.S.; Stone, M.L. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States); Singler, R.E. [Military Academy, West Point, NY (United States). Dept. of Chemistry
It was observed that competitive nucleophilic addition processes may be observed by {sup 31}P NMR spectroscopy. Methoxyethoxyethanol (MEE) and p-methoxyphenol readily substitute for chlorineonto phosphorus and the relative rates are generally comparable to each other. Sterically, the phenol presents is slightly larger than MEE but this does not appear to effect substitution judging by the observed PN(OAr){sub 2} NMR signal. These processes are still being studied.
Conversion factors for carbohydrate analysis by hydrolysis and 1 H-NMR spectroscopy
Soo-Jeong Shin; Nam-Seok Cho
Conversion factor to calibrate the lower xylan content in carbohydrate compositional analysis in wood by 1H-NMR spectroscopy was investigated. During acid hydrolysis, xylan monomer was dehydrated as furfural, and that furfural was\\u000a further degraded or condensed in acidic reaction condition. Anomeric hydrogen peaks integration in 1H-NMR spectroscopic method excluded xylose reacted products (such as furfural and their condensed or degraded
Polydimethylsiloxane: a general matrix for high-performance chromatographic NMR spectroscopy.
Huang, Shaohua; Gao, Jun; Wu, Rui; Li, Shengying; Bai, Zhengwu
The detection and structural characterization of the components of a mixture is a challenging task. Therefore, the development of a facile and general method that enables both the separation and the structural characterization of the components is desired. Diffusion-ordered NMR spectroscopy (DOSY) with the aid of a matrix is a promising tool for this purpose. However, because the currently existing matrices only separate limited components, the application of the DOSY technique is restricted. Herein we introduce a new versatile matrix, poly(dimethylsiloxane), which can fully separate many mixtures of different structural types by liquid-state NMR spectroscopy. With poly(dimethylsiloxane), liquid-state chromatographic NMR spectroscopy could become a general approach for the structural elucidation of mixtures of compounds. PMID:25196825
Applications of toroids in high-pressure NMR spectroscopy
Klingler, R.J.; Rathke, J.W.; Woelk, K. [and others
Toroid detectors have distinct NMR sensitivity and imaging advantages. The magnetic field lines are nearly completely contained within the active volume element of a toroid. This results in high NMR signal sensitivity. In addition, the toroid detector may be placed next to the metallic walls of a containment vessel with minimal signal loss due to magnetic coupling with the metal container. Thus, the toroid detector is ideal for static high pressure or continuous flow monitoring systems. Toroid NMR detectors have been used to follow the hydroformylation of olefins in supercritical fluids under industrial process conditions. Supercritical fluids are potentially ideal media for conducting catalytic reactions that involve gaseous reactants, including H{sub 2}, CO, and CO{sub 2}. The presence of a single homogeneous reaction phase eliminates the gas-liquid mixing problem of alternative two-phase systems, which can limit process rates and adversely affect hydroformylation product selectivities. A second advantage of toroid NMR detectors is that they exhibit a well-defined gradient in the rf field. This magnetic field gradient can be used for NMR imaging applications. Distance resolutions of 20 {mu} have been obtained.
Applications of toroids in high-pressure NMR spectroscopy
Klingler, R.J.; Rathke, J.W.; Woelk, K.; Kramarz, K.W.; Gerald, R. [Argonne National Lab., IL (United States)
Toroid detectors have distinct NMR sensitivity and imaging advantages. The magnetic field lines are nearly completely contained within the active volume element of a toroid. This results in high NMR signal sensitivity. In addition, the toroid detector may be placed next to the metallic walls of a containment vessel with minimal signal loss due to magnetic coupling with the metal container. Thus, the toroid detector is ideal for static high pressure or continuous flow monitoring systems. Toroid NMR detectors have been used to follow the hydroformylation of olefins in supercritical fluids under industrial process conditions. Supercritical fluids are potentially ideal media for conducting catalytic reactions that involve gaseous reactants, including H{sub 2}, CO, and CO{sub 2}. The presence of a single homogeneous reaction phase eliminates the gas-liquid mixing problem of alternative two-phase systems, which can limit process rates and adversely affect hydroformylation product selectivities. A second advantage of toroid NMR detectors is that they exhibit a well-defined gradient in the rf field. This magnetic field gradient can be used for NMR imaging applications. Distance resolutions of 20 {mu} have been obtained.
Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises
ERIC Educational Resources Information Center
Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda
This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrationalģ
Ratio Analysis NMR Spectroscopy (RANSY) for Selective Metabolite Identification in Complex Samples
Wei, Siwei; Zhang, Jian; Liu, Lingyan; Ye, Tao; Nagana Gowda, G. A.; Tayyari, Fariba; Raftery, Daniel
Metabolite identification in the complex NMR spectra of biological samples is a challenging task due to significant spectral overlap and limited signal to noise. In this study we present a new approach, RANSY (Ratio Analysis NMR Spectroscopy), which identifies all the peaks of a specific metabolite based on the ratios of peak heights or integrals. We show that the spectrum for an individual metabolite can be generated by exploiting the fact that the peak ratios for any metabolite in the NMR spectrum are fixed and proportional to the relative numbers of magnetically distinct protons. When the peak ratios are divided by their coefficient of variations derived from a set of NMR spectra, the generation of an individual metabolite spectrum is enabled. We first tested the performance of this approach using one-dimensional (1D) and two-dimensional (2D) NMR data of mixtures of synthetic analogues of common body fluid metabolites. Subsequently, the method was applied to 1H NMR spectra of blood serum samples to demonstrate the selective identification of a number of metabolites. The RANSY approach, which does not need any additional NMR experiments for spectral simplification, is easy to perform and has the potential to aid in the identification of unknown metabolites using 1D or 2D NMR spectra in virtually any complex biological mixture. PMID:21894988
Characterization of the essential oil of Agastache rugosa by NMR spectroscopy
NASA Astrophysics Data System (ADS)
Skakovskii, E. D.; Kiselev, W. P.; Tychinskaya, L. Yu.; Schutova, A. G.; Gonsharova, L. W.; Spiridowish, E. W.; Bovdey, N. A.; Kiselev, P. A.; Gaidukevich, O. A.
The composition of essential oil from Agastache rugosa (Fish. et Mey) O.Kuntze was studied by 1H and 13C NMR spectroscopy. Essential oil was isolated from the aerial part of plants growing in the Central Botanical Garden of the NAS of Belarus during flowering and fruiting. The oil chemical composition was found to depend little on the sampling time. It was shown that NMR spectroscopy could be successfully used to both monitor the content of the hepatotoxic substance (pulegone) and characterize the quality and authenticity of essential oils.
Quantitating Metabolites in Protein Precipitated Serum Using NMR Spectroscopy
Quantitative NMR-based metabolite profiling is challenged by the deleterious effects of abundant proteins in the intact blood plasma/serum, which underscores the need for alternative approaches. Protein removal by ultrafiltration using low molecular weight cutoff filters thus represents an important step. However, protein precipitation, an alternative and simple approach for protein removal, lacks detailed quantitative assessment for use in NMR based metabolomics. In this study, we have comprehensively evaluated the performance of protein precipitation using methanol, acetonitrile, perchloric acid, and trichloroacetic acid and ultrafiltration approaches using 1D and 2D NMR, based on the identification and absolute quantitation of 44 human blood metabolites, including a few identified for the first time in the NMR spectra of human serum. We also investigated the use of a ōsmart isotope tag,ö 15N-cholamine for further resolution enhancement, which resulted in the detection of a number of additional metabolites. 1H NMR of both protein precipitated and ultrafiltered serum detected all 44 metabolites with comparable reproducibility (average CV, 3.7% for precipitation; 3.6% for filtration). However, nearly half of the quantified metabolites in ultrafiltered serum exhibited 10¢74% lower concentrations; specifically, tryptophan, benzoate, and 2-oxoisocaproate showed much lower concentrations compared to protein precipitated serum. These results indicate that protein precipitation using methanol offers a reliable approach for routine NMR-based metabolomics of human blood serum/plasma and should be considered as an alternative to ultrafiltration. Importantly, protein precipitation, which is commonly used by mass spectrometry (MS), promises avenues for direct comparison and correlation of metabolite data obtained from the two analytical platforms to exploit their combined strength in the metabolomics of blood. PMID:24796490
High-resolution solid-state NMR spectroscopy in studies of conversions of hydrocarbons and alcohols on zeolites
NASA Astrophysics Data System (ADS)
Stepanov, Alexander G.
The review surveys advances in high-resolution solid-state 1H and 13C NMR spectroscopy applied to studies of conversions of hydrocarbons and alcohols on zeolite catalysts of an acidic nature. The potential of NMR spectroscopy in studies of mechanisms of chemical reactions and analysis of compounds formed in situ is considered. The bibliography includes 134 references.
Analysis of illegally manufactured formulations of tadalafil (Cialis «) by 1H NMR, 2D DOSY 1H NMR and Raman spectroscopy
Saleh Trefi; Corinne Routaboul; Saleh Hamieh; Vķronique Gilard; Myriam Malet-Martino; Robert Martino
Counterfeit and\\/or imitation medicines are becoming a major health problem not only in developing countries but also in wealthier countries. The need of new and easy analytical methods for quality control of drugs is essential. We describe the use of Raman spectroscopy, 1H nuclear magnetic resonance (NMR) and 2D diffusion-ordered spectroscopy (DOSY) NMR to analyse genuine Cialis« and seven illegally
From Molecular Structure to Global Processes : NMR Spectroscopy in Analytical/Environmental Chemistry
NASA Astrophysics Data System (ADS)
Simpson, A.
NMR Spectroscopy is arguably the most powerful tool to elucidate structure and probe molecular interactions. A range of NMR approaches will be introduced with emphasis on addressing and understanding structure and reactivity of soil organic matter at the molecular level. The presentation will be split into three main sections. The first section will look at evidence from advanced NMR based approaches that when considered synergistically describes the major structural components in soil organic matter. Multidimensional NMR spectroscopy (1-3D NMR), automated pattern matching, spectral simulations, diffusion NMR and hybrid-diffusion NMR will be introduced in context of molecular structure. Finally the structural components in soil will be contrasted to those found in aquatic dissolved organic matter. Secondly molecular interactions of natural organic matter will be considered. Advanced structural studies have provided detailed spectral assignments which in turn permit the reactivity of various soil components to be elucidated. Aggregation and self-association of soil and dissolved organic matter will be discussed along with the structural components likely responsible for aggregation/colloid formation. Interactions of soil organic matter with anthropogenic chemicals will also be considered and NMR techniques based on "Saturation Transfer Difference" introduced. These techniques are extremely powerful and can be used to both; describe mechanistically how anthropogenic chemicals sorb to whole soils and identify the structural components (lignin, protein, cellulose, etc..) that are responsible for the binding/sorption in soil. In the last section, the "big questions" and challenges facing the field will be considered along with some novel experimental NMR based approaches that should, in future, assist in providing answers to these questions.
Ultrafast two-dimensional NMR spectroscopy using constant acquisition gradients
Frydman, Lucio
of such fast-switching scheme may also arise due to gradient-induced perineural stimulation. The present study magnetic resonance nD NMR plays a central role in numerous areas of contempo- rary research. It serves as a basis for numerous in vitro analy- ses of molecular structure and dynamics, and acts as a basic tool
NMR Planar Micro coils for micro spectroscopy: Design and characterisation
N. Baxan; A. Rengle; J.-F. Chateaux; A. Briguet; G. Pasquet; P. Morin; L. Fakri-Bouchet
The goal of this study is to determine the concentration sensitivity and the limit of detection of a SNMR receiver planar micro coil with ellipsoidal geometry 1000times500 mum, fabricated using an electroplating technique and used as SNMR receiver coil at 200 MHz. The maximum signal intensity on the NMR images and simulation of RF field distribution allows defining an active
Protein folding and unfolding studied at atomic resolution by fast two-dimensional NMR spectroscopy
Schanda, Paul; Forge, Vincent; Brutscher, Bernhard
Atom-resolved real-time studies of kinetic processes in proteins have been hampered in the past by the lack of experimental techniques that yield sufficient temporal and atomic resolution. Here we present band-selective optimized flip-angle short transient (SOFAST) real-time 2D NMR spectroscopy, a method that allows simultaneous observation of reaction kinetics for a large number of nuclear sites along the polypeptide chain of a protein with an unprecedented time resolution of a few seconds. SOFAST real-time 2D NMR spectroscopy combines fast NMR data acquisition techniques with rapid sample mixing inside the NMR magnet to initiate the kinetic event. We demonstrate the use of SOFAST real-time 2D NMR to monitor the conformational transition of ?-lactalbumin from a molten globular to the native state for a large number of amide sites along the polypeptide chain. The kinetic behavior observed for the disappearance of the molten globule and the appearance of the native state is monoexponential and uniform along the polypeptide chain. This observation confirms previous findings that a single transition state ensemble controls folding of ?-lactalbumin from the molten globule to the native state. In a second application, the spontaneous unfolding of native ubiquitin under nondenaturing conditions is characterized by amide hydrogen exchange rate constants measured at high pH by using SOFAST real-time 2D NMR. Our data reveal that ubiquitin unfolds in a gradual manner with distinct unfolding regimes. PMID:17592113
The use of NMR spectroscopy to validate NMR logs from deeply buried reservoir sandstones
H RueslÕtten; T Eidesmo; K. A Lehne; O. M Relling
A Lower Jurassic deeply buried sandstone oil reservoir offshore Mid Norway was logged with NUMAR's MRIL-C tool. The NML data have been compared with standard logs as well as laboratory NMR and standard petrophysical core measurements. The two formations studied are in the oil zone, Formation A being characterised by an extensive distribution of pore lining chlorite, while asphalt staining
A review of Blind Source Separation in NMR Spectroscopy
2014 Author manuscript, published in "Progress in Nuclear Magnetic Resonance Spectroscopy 81 (2014) 37 products or elusive metabolites) or to extract cumulative spectral features descriptive of a sample
Geometry of tricyclic quinolizidine-piperidine alkaloids in solution by NMR spectroscopy
NASA Astrophysics Data System (ADS)
Brukwicki, Tadeusz; Wysocka, Waleria
The Haasnoot equation was used to determine HCCH spectroscopy dihedral angles from 1H NMR spectroscopy in tricyclic quinolizidine-piperidine alkaloids in solution: seco(11,12)- 12,13-didehydromultiflorine (1), seco(11,12)- 5,6-didehydromultiflorine (2) and angustifoline (3). Ring C in the three alkaloids has quite a regular chair conformation. Ring B is a flattened chair in 1 and 3 and a sofa in 2. The geometry of 2 is similar to that of cytisine (4).
Simultaneous 19F-1H medium resolution NMR spectroscopy for online reaction monitoring
NASA Astrophysics Data System (ADS)
Zientek, Nicolai; Laurain, Clķment; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael
Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16? fluorinated ethylene propylene (FEP) tube with an ID of 0.04? (1.02 mm) was used as a flow cell in combination with a 5 mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32 MHz and 40.68 MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500 MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16? FEP tube set-up with an ID of 1.02 mm was characterised regarding the limit of detection (LOQ (1H) = 0.335 mol L-1 and LOQ (19F) = 0.130 mol L-1 for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3 mL min-1. Thus, a series of single scan 19F and 1H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring.
Simultaneous (19)F-(1)H medium resolution NMR spectroscopy for online reaction monitoring.
Zientek, Nicolai; Laurain, Clķment; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael
Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16? fluorinated ethylene propylene (FEP) tube with an ID of 0.04? (1.02mm) was used as a flow cell in combination with a 5mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a (1)H Larmor frequency of 43.32MHz and 40.68MHz for (19)F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating (19)F and (1)H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16? FEP tube set-up with an ID of 1.02mm was characterised regarding the limit of detection (LOQ ((1)H)=0.335molL(-1) and LOQ ((19)F)=0.130molL(-1) for trifluoroethanol in D2O (single scan)) and maximum quantitative flow rates up to 0.3mLmin(-1). Thus, a series of single scan (19)F and (1)H NMR spectra acquired with this simple set-up already presents a valuable basis for quantitative reaction monitoring. PMID:25462947
Supramolecular complex formed by DNA oligonucleotide and thiacalix[4]arene. NMR-spectroscopy and molecular docking
NASA Astrophysics Data System (ADS)
Khairutdinov, Bulat; Ermakova, Elena; Sitnitsky, Aleksandr; Stoikov, Ivan; Zuev, Yuriy
The combination of NMR-spectroscopy and molecular docking was applied to investigate the complexation of thiacalix[4]arene with DNA. We have studied the structure of supramolecular complex formed by palindromic decamer DNA d(GCGTTAACGC)2 and tetrasubstituted at lower rim of p-tert-butyl thiacalix[4]arene in 1,3-alternate conformation. With the help of NMR it is shown that oligonucleotide in solution exists in two states: double-stranded helix (dominant structure in solution) and single-stranded form (minor structure) rolled up in a ōhairpinö with equilibrium between them. Both complementary methods, NMR and molecular docking, revealed the formation of molecular complex by thiacalix[4]arene and palindromic decamer DNA. Different possible conformations of the complexes were analyzed by means of molecular docking. We used the experimental constraints in molecular docking to identify the complexes, which were in agreement with the NMR data.
Slow-spinning low-sideband HR-MAS NMR spectroscopy: delicate analysis of biological samples
Renault, Marie; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano
High-Resolution Magic-Angle Spinning (HR-MAS) NMR spectroscopy has become an extremely versatile analytical tool to study heterogeneous systems endowed with liquid-like dynamics. Spinning frequencies of several kHz are however required to obtain NMR spectra, devoid of spinning sidebands, with a resolution approaching that of purely isotropic liquid samples. An important limitation of the method is the large centrifugal forces that can damage the structure of the sample. In this communication, we show that optimizing the sample preparation, particularly avoiding air bubbles, and the geometry of the sample chamber of the HR-MAS rotor leads to high-quality low-sideband NMR spectra even at very moderate spinning frequencies, thus allowing the use of well-established solution-state NMR procedures for the characterization of small and highly dynamic molecules in the most fragile samples, such as live cells and intact tissues. PMID:24284435
Slow-spinning low-sideband HR-MAS NMR spectroscopy: delicate analysis of biological samples
NASA Astrophysics Data System (ADS)
Renault, Marie; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano
High-Resolution Magic-Angle Spinning (HR-MAS) NMR spectroscopy has become an extremely versatile analytical tool to study heterogeneous systems endowed with liquid-like dynamics. Spinning frequencies of several kHz are however required to obtain NMR spectra, devoid of spinning sidebands, with a resolution approaching that of purely isotropic liquid samples. An important limitation of the method is the large centrifugal forces that can damage the structure of the sample. In this communication, we show that optimizing the sample preparation, particularly avoiding air bubbles, and the geometry of the sample chamber of the HR-MAS rotor leads to high-quality low-sideband NMR spectra even at very moderate spinning frequencies, thus allowing the use of well-established solution-state NMR procedures for the characterization of small and highly dynamic molecules in the most fragile samples, such as live cells and intact tissues.
Slow-spinning low-sideband HR-MAS NMR spectroscopy: delicate analysis of biological samples.
Renault, Marie; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano
High-Resolution Magic-Angle Spinning (HR-MAS) NMR spectroscopy has become an extremely versatile analytical tool to study heterogeneous systems endowed with liquid-like dynamics. Spinning frequencies of several kHz are however required to obtain NMR spectra, devoid of spinning sidebands, with a resolution approaching that of purely isotropic liquid samples. An important limitation of the method is the large centrifugal forces that can damage the structure of the sample. In this communication, we show that optimizing the sample preparation, particularly avoiding air bubbles, and the geometry of the sample chamber of the HR-MAS rotor leads to high-quality low-sideband NMR spectra even at very moderate spinning frequencies, thus allowing the use of well-established solution-state NMR procedures for the characterization of small and highly dynamic molecules in the most fragile samples, such as live cells and intact tissues. PMID:24284435
Citron and lemon under the lens of HR-MAS NMR spectroscopy.
Mucci, Adele; Parenti, Francesca; Righi, Valeria; Schenetti, Luisa
High Resolution Magic Angle Spinning (HR-MAS) is an NMR technique that can be applied to semi-solid samples. Flavedo, albedo, pulp, seeds, and oil gland content of lemon and citron were studied through HR-MAS NMR spectroscopy, which was used directly on intact tissue specimens without any physicochemical manipulation. HR-MAS NMR proved to be a very suitable technique for detecting terpenes, sugars, organic acids, aminoacids and osmolites. It is valuable in observing changes in sugars, principal organic acids (mainly citric and malic) and ethanol contents of pulp specimens and this strongly point to its use to follow fruit ripening, or commercial assessment of fruit maturity. HR-MAS NMR was also used to derive the molar percentage of fatty acid components of lipids in seeds, which can change depending on the Citrus species and varieties. Finally, this technique was employed to elucidate the metabolic profile of mold flavedo. PMID:23871074
A broad-banded z-rotation windowed phase-modulated Lee Goldburg pulse sequence for 1H spectroscopy in solid-state NMR
NASA Astrophysics Data System (ADS)
Leskes, Michal; Madhu, P. K.; Vega, Shimon
High-resolution 1H spectroscopy in solid-state NMR, rendered difficult due to the strong 1H- 1H homonuclear dipolar coupling, has been made possible under magic-angle spinning with homonuclear dipolar decoupling schemes, such as windowed phase-modulated Lee-Goldburg. Here, we outline the theory and implementation of a modification of this scheme with which an effective z-rotation for the magnetisation is obtained over a wide range of spectral window. Experimental results are presented for samples, such as glycine, histidine, and tryosine.
High-Resolution 1H NMR Micro spectroscopy using an Implantable Micro-coil
N. Baxan; A. Rengle; A. Briguet; L. Fakri-Bouchet; J.-F. Chateaux; G. Pasquet; P. Morin
This study presents a new concept of implantable micro coil (1000 times 500 mum2) fabricated using an electroplating technique, used as receiver coil at 200 MHz for the measurement of small volumes and concentrations samples by NMR spectroscopy. Our goal is to determine its concentration sensitivity Sc and its limit of detection LOD. The MRI and simulation of RF field
Sensitivity Enhancement in 1D Heteronuclear NMR Spectroscopy via Single-Scan Inverse
Frydman, Lucio
Sensitivity Enhancement in 1D Heteronuclear NMR Spectroscopy via Single-Scan Inverse Experiments of the present article to discuss the possi- bility of retaining some of the indirect-detection sensitivity ad, however, make the sensitivity of this kind of spec- troscopy inherently lower than that of comparable 1 H
High-Resolution Solid-State NMR Spectroscopy: Characterization of Polymorphism in Cimetidine, a Pharmaceutical Compound
ERIC Educational Resources Information Center
Pacilio, Julia E.; Tokarski, John T.; Qui±ones, Rosalynn; Iuliucci, Robbie J.
High-resolution solid-state NMR (SSNMR) spectroscopy has many advantages as a tool to characterize solid-phase material that finds applications in polymer chemistry, nanotechnology, materials science, biomolecular structure determination, and others, including the pharmaceutical industry. The technology associated with achieving high resolutionģ
Characterization of various fast pyrolysis bio-oils by NMR spectroscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
NMR spectroscopy, including 1H, 13 C and DEPT spectra were used to characterize fast pyrolysis oil from numerous energy crops and other agricultural feedstocks. The bio-oils studied were produced from swithchgrass, alfalfa stems, corn stover, guayule (whole plant and latex extracted bagasse) and ch...
Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy
Frydman, Lucio
Real-Time Monitoring of Chemical Transformations by Ultrafast 2D NMR Spectroscopy Maayan Gal, Mor concerns the monitoring of chemical transformations as they happen, in real time. The present paper dissolving a protonated protein in D2O, and (ii) real-time in situ tracking of a transient Meisenheimer
DHA and EPA Interaction with Raft Domains Observed With Solid-State 2 H NMR Spectroscopy
Zhou, Yaoqi
DHA and EPA Interaction with Raft Domains Observed With Solid-State 2 H NMR Spectroscopy Jacob J, and docosahexaenoic acid (DHA, 22:6), with 22 carbons and 6 double bonds. However, their molecular modes of action and PDPC with a perdeuterated palmitoyl sn-1 chain, showed that DHA has a greater tendency than EPA
Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory
ERIC Educational Resources Information Center
Pavel, John T.; Hyde, Erin C.; Bruch, Martha D.
This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possibleģ
NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation
Richards, T.
NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures.
Softening of Membrane Bilayers by Detergents Elucidated by Deuterium NMR Spectroscopy
Brown, Michael F.
Softening of Membrane Bilayers by Detergents Elucidated by Deuterium NMR Spectroscopy Do1rte Otten-sn-glycero-3-phosphocholine (DMPC) was compared with DMPC containing a nonionic detergent as an additive. Order (DMPC-d54). A reduction of the order parameters of DMPC-d54 in the presence of the detergent
High Resolution NMR Spectroscopy of Nanocrystalline Proteins at Ultra-High Magnetic Field
Sperling, Lindsay J.; Nieuwkoop, Andrew J.; Lipton, Andrew S.; Berthold, Deborah A.; Rienstra, Chad M.
Solid-state NMR (SSNMR) spectroscopy is a powerful tool for studying protein structure and function, uniquely able to address macroscopically disordered proteins. Insights from SSNMR include atomic-resolution structure, site-specific dynamics, metal center chemistry, and orientation of membrane proteins in bilayers.
Introducing High School Students to NMR Spectroscopy through Percent Composition Determination Using Low-Field Spectrometers
ERIC Educational Resources Information Center
Bonjour, Jessica L.; Pitzer, Joy M.; Frost, John A.
Mole to gram conversions, density, and percent composition are fundamental concepts in first year chemistry at the high school or undergraduate level; however, students often find it difficult to engage with these concepts. We present a simple laboratory experiment utilizing portable nuclear magnetic resonance spectroscopy (NMR) to determine theģ
Sensitivity enhancement of double quantum NMR spectroscopy by modified CPMG
NASA Astrophysics Data System (ADS)
Gowda, Chandrakala M.; Agarwal, Vipin; Kentgens, Arno P. M.
A modified Carr-Purcell-Meiboom-Gill (CPMG) sequence for sensitivity enhancement of dipolar coupled homonuclear spin pairs in static solid-state NMR is presented. The modified CPMG block uses the Hahn-solid-Hahn echo as basic element of the CPMG echo train to refocus the homonuclear dipolar coupling and chemical shift anisotropy. The new CPMG sequence is dubbed as Hahn-solid-Hahn Carr-Purcell-Meiboom-Gill (HSHCPMG). We demonstrate a gain in signal to noise ratio of approximately 4.2 using HSHCPMG sequence in double quantum filtered CP experiment for 5%-13C2-15N-glycine. The resulting gain in sensitivity in the spikelet spectrum does not compromise the anisotropic information that is available from static NMR lineshapes. As an example, relative orientation angles of chemical shift anisotropy tensors for the alpha and carbonyl carbons in glycine are determined from the 2D DOQSY experiment recorded with the HSHCPMG block in the acquisition dimension. The resultant relative orientation angles of the two CSA tensors are compared to those obtained from 2D DOQSY experiment acquired without sensitivity enhancement as well as to the data as available from single crystal NMR experiments.
NMRFAM-SPARKY: enhanced software for biomolecular NMR spectroscopy
Lee, Woonghee; Tonelli, Marco; Markley, John L.
Summary: SPARKY (Goddard and Kneller, SPARKY 3) remains the most popular software program for NMR data analysis, despite the fact that development of the package by its originators ceased in 2001. We have taken over the development of this package and describe NMRFAM-SPARKY, which implements new functions reflecting advances in the biomolecular NMR field. NMRFAM-SPARKY has been repackaged with current versions of Python and Tcl/Tk, which support new tools for NMR peak simulation and graphical assignment determination. These tools, along with chemical shift predictions from the PACSY database, greatly accelerate protein side chain assignments. NMRFAM-SPARKY supports automated data format interconversion for interfacing with a variety of web servers including, PECAN , PINE, TALOS-N, CS-Rosetta, SHIFTX2 and PONDEROSA-C/S. Availability and implementation: The software package, along with binary and source codes, if desired, can be downloaded freely from http://pine.nmrfam.wisc.edu/download_packages.html. Instruction manuals and video tutorials can be found at http://www.nmrfam.wisc.edu/nmrfam-sparky-distribution.htm. Contact: firstname.lastname@example.com or email@example.com Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25505092
Heteronuclear NMR spectroscopy as a surface-selective technique: a unique look at the hydroxyl groups of ?-alumina.
Taoufik, Mostafa; Szeto, Kai C; Merle, Nicolas; Del Rosal, Iker; Maron, Laurent; Trķbosc, Julien; Tricot, Grķgory; Gauvin, Rķgis M; Delevoye, Laurent
The surface hydroxyl groups of ?-alumina dehydroxylated at 500?░C were studied by a combination of one- and two-dimensional homo- and heteronuclear (1)H and (27)Al NMR spectroscopy at high magnetic field. In particular, by harnessing (1)H-(27) Al dipolar interactions, a high selectivity was achieved in unveiling the topology of the alumina surface. The terminal versus bridging character of the hydroxyl groups observed in the (1)H magic-angle spinning (MAS) NMR spectrum was demonstrated thanks to (1)H-(27) Al RESPDOR (resonance-echo saturation-pulse double-resonance). In a further step the hydroxyl groups were assigned to their aluminium neighbours thanks to a {(1)H}-(27) Al dipolar heteronuclear multiple quantum correlation (D-HMQC), which was used to establish a first coordination map. Then, in combination with (1)H-(1) H double quantum (DQ) MAS, these elements helped to reveal intimate structural features of the surface hydroxyls. Finally, the nature of a peculiar reactive hydroxyl group was demonstrated following this methodology in the case of CO2 reactivity with alumina. PMID:24604836
Identification of endogenous metabolites in human sperm cells using proton nuclear magnetic resonance ((1) H-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).
Paiva, C; Amaral, A; Rodriguez, M; Canyellas, N; Correig, X; BallescÓ, J L; Ramalho-Santos, J; Oliva, R
The objective of this study was to contribute to the first comprehensive metabolomic characterization of the human sperm cell through the application of two untargeted platforms based on proton nuclear magnetic resonance ((1) H-NMR) spectroscopy and gas chromatography coupled to mass spectrometry (GC-MS). Using these two complementary strategies, we were able to identify a total of 69 metabolites, of which 42 were identified using NMR, 27 using GC-MS and 4 by both techniques. The identity of some of these metabolites was further confirmed by two-dimensional (1) H-(1) H homonuclear correlation spectroscopy (COSY) and (1) H-(13) C heteronuclear single-quantum correlation (HSQC) spectroscopy. Most of the metabolites identified are reported here for the first time in mature human spermatozoa. The relationship between the metabolites identified and the previously reported sperm proteome was also explored. Interestingly, overrepresented pathways included not only the metabolism of carbohydrates, but also of lipids and lipoproteins. Of note, a large number of the metabolites identified belonged to the amino acids, peptides and analogues super class. The identification of this initial set of metabolites represents an important first step to further study their function in male gamete physiology and to explore potential reasons for dysfunction in future studies. We also demonstrate that the application of NMR and MS provides complementary results, thus constituting a promising strategy towards the completion of the human sperm cell metabolome. PMID:25854681
Characterisation of oxidised 7Fe dicluster ferredoxins with NMR spectroscopy.
Hannan, J P; Busch, J L; Breton, J; James, R; Thomson, A J; Moore, G R; Davy, S L
Dicluster ferredoxins (Fds) from Sulfolobus acidocaldarius and Desulfovibrio africanus (FdIII) have been studied using 1H NMR. Both wild-type proteins contain a [3Fe-4S]+/0 and a [4Fe-4S]2+/+ cluster as isolated. The [4Fe-4S]2+/+ cluster (cluster II) is bound by cysteine residues arranged in a classic ferredoxin motif: CysI-(Xaa)2-CysII-(Xaa)2-CysIII-(Xaa)n-CysIV-Pro , whilst the binding motif of the [3Fe-4S]+/0 cluster (cluster I) has a non-ligating aspartic acid (Asp14) at position II, i.e. CysI-(Xaa)2-Asp-(Xaa)2-CysIII. D. africanus FdIII undergoes facile cluster transformation from the 7Fe form to the 8Fe form, but S. acidocaldarius Fd does not. Many factors determine the propensity of a cluster to undergo interconversion, including the presence, and correct orientation, of a suitable ligand. We have investigated this using 1H NMR by introducing a potential fourth ligand into the binding motif of cluster I of D. africanus FdIII. Asp14 has been mutated to cysteine (D14C), glutamic acid (D14E) and histidine (D14H). Cluster incorporation was performed in vitro. The cluster types present were identified from the chemical shift patterns and temperature-dependent behaviour of the hyperfine-shifted resonances. Factors influencing cluster ligation and cluster interconversion, in vitro, are discussed. Furthermore, the data have established that the residue at position II in the cluster binding motif of cluster I is influential in determining the chemical shift pattern observed for a [3Fe-4S]+ cluster when a short/symmetric binding motif is present. Based on this, a series of rules for characterising the 1H NMR chemical shifts of mono- and di-cluster [3Fe-4S]+ cluster-containing ferredoxins is given. PMID:10968614
Pushing the Limits of NMR Spectroscopy: In Situ analysis of Organic Matter in Natural Waters
NASA Astrophysics Data System (ADS)
Simpson, A.; Lam, B.
Dissolved Organic Matter (DOM) is ubiquitous in all natural waters and is known to play important roles in the carbon and nitrogen cycles, the transport and transformation of contaminants and nutrients, and health and biodiversity of aquatic species. Thus there is a great scientific need to further understand the composition, variability and reactivity of dissolved organic matter in the environment. Of all the analytical approaches employed to study DOM, NMR spectroscopy has provided the greatest insights into its general composition. However, conventional NMR studies often require a considerable amount of isolated DOM (mg quantities) and are adversely influenced by high salt and/or metal content which can result from sample concentration. Also there is concern that DOM can be altered during chemical isolation to varying extents and may not be completely representative of the material in its natural state. Here we demonstrate, that while very difficult, it is possible to obtain NMR spectra of Organic Matter in situ for practically all major bodies of water including groundwater, rainwater, seawater, and water from lakes and rivers. In sea water DOM is present at ~1ppm, and thus with a standard 5mm NMR probe (assuming ~300ĄL volume inside the coil), only ~300ng of DOM is present. Furthermore, considering that the intensity of the water signal is many orders of magnitude greater than the weak signals from the DOM (itself a heterogeneous mixture) it is clear that such applications challenge the limits of modern NMR spectroscopy.
New methods and applications in solid-state NMR spectroscopy of quadrupolar nuclei.
Ashbrook, Sharon E; Sneddon, Scott
Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future. PMID:25296129
RNA nucleosides as chiral sensing agents in NMR spectroscopy.
Lokesh, N; Sachin, S L; Narendra, L V; Arun, K; Suryaprakash, N
The study reports chiral sensing properties of RNA nucleosides. Adenosine, guanosine, uridine and cytidine are used as chiral derivatizing agents to differentiate chiral 1░-amines. A three component protocol has been adopted for complexation of nucleosides and amines. The chiral differentiating ability of nucleosides is examined for different amines based on the (1)H NMR chemical shift differences of diastereomers (??(R,S)). Enantiomeric differentiation has been observed at multiple chemically distinct proton sites. Adenosine and guanosine exhibit large chiral differentiation (??(R,S)) due to the presence of a purine ring. The diastereomeric excess (de) measured by using adenosine is in good agreement with the gravimetric values. PMID:26054739
Mobility and relaxation determinations of lithium in lithium aluminate ceramics using solid-state NMR spectroscopy
Stewart, F.F.; Peterson, E.S. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Stebbins, J.F. [Stanford Univ., CA (United States)] [and others
Lithium aluminate is one of the materials being considered for fusion reactor blankets. When preparing the ceramic, it is important to be able to monitor the microstructures since it is a controlling factor in the rate of tritium release from the blanket. Nuclear magnetic resonance spectroscopy (NMR) has been shown to be a useful tool for the nondestructive analysis of ceramics. Studies detailed in this paper include spectral acquisition, assignment, spin-lattice relaxation time measurements, temperature effects, their correlation to structure, and material purity. The ceramic of interest was lithium aluminate, LiAl{sub 5}O{sub 8}. This material was studied by observation of the NMR active nuclei {sup 6}Li, {sup 7}Li, and {sup 27}Al. For these nuclei, spin-lattice relaxation times (T{sub 1}) were measured and were found to vary considerably, correlating to the presence of paramagnetic impurities within the crystalline lattice. Previous research has shown that the coordination about the aluminum nucleus can be determined using {sup 27}Al NMR spectroscopy. Aluminum-27 NMR spectroscopy was successfully applied, and it provided valuable insight into composition of the ceramic. 20 refs., 4 figs., 3 tabs.
Water Behavior in Bacterial Spores by Deuterium NMR Spectroscopy
Dormant bacterial spores are able to survive long periods of time without nutrients, withstand harsh environmental conditions, and germinate into metabolically active bacteria when conditions are favorable. Numerous factors influence this hardiness, including the spore structure and the presence of compounds to protect DNA from damage. It is known that the water content of the spore core plays a role in resistance to degradation, but the exact state of water inside the core is a subject of discussion. Two main theories present themselves: either the water in the spore core is mostly immobile and the core and its components are in a glassy state, or the core is a gel with mobile water around components which themselves have limited mobility. Using deuterium solid-state NMR experiments, we examine the nature of the water in the spore core. Our data show the presence of unbound water, bound water, and deuterated biomolecules that also contain labile deuterons. Deuterium¢hydrogen exchange experiments show that most of these deuterons are inaccessible by external water. We believe that these unreachable deuterons are in a chemical bonding state that prevents exchange. Variable-temperature NMR results suggest that the spore core is more rigid than would be expected for a gel-like state. However, our rigid core interpretation may only apply to dried spores whereas a gel core may exist in aqueous suspension. Nonetheless, the gel core, if present, is inaccessible to external water. PMID:24950158
Positional isotope exchange studies on enzyme using NMR spectroscopy
Matsunaga, T.O.
The isotopically enriched compounds, /sup 18/O-..beta..,..gamma..-ATP and /sup 18/O bridge-labeled pyrophosphate, synthesized previously in this laboratory, were used to investigate and measure the exchange vs. turnover of substrates and products from their central complexes in four selected enzyme systems. Using hi-field /sup 31/P NMR, we were able to differentiate between /sup 18/O labeled in the bridge vs. the non-bridge positions by virtue of the isotope shift upon the phosphorus nuclei. The bridge to non-bridge scrambling of the label was quantitated and the exchange vs. turnover ratios under a variety of conditions was determined. Using the substrate inhibitor carboxycreatinine, PIX experiments with /sup 18/O-..beta..,..gamma..-ATP and creatine kinase were conducted. It was shown that carboxycreatinine and creatine kinase promoted exchange of the /sup 18/O label as determined by NMR. We have concluded that carboxycreatinine is either a substrate that catalyzes very slow turnover or it catalyzes exchange by a dissociative (SN/sub 1//sub P/) type of mechanism
Insights into Atomic-level Interaction between Mefenamic Acid and Eudragit« EPO in a Supersaturated Solution by High-Resolution Magic-Angle Spinning NMR Spectroscopy
Higashi, Kenjirou; Yamamoto, Kazutoshi; Pandey, Manoj Kumar; Mroue, Kamal H.; Moribe, Kunikazu; Yamamoto, Keiji; Ramamoorthy, Ayyalusamy
The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble non-steroidal anti-inflammatory drug, and Eudragit« EPO (EPO), a water-soluble polymer, is investigated in their supersaturated solution using high-resolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable supersaturated solution with a high MFA concentration of 3.0 mg/mL is prepared by dispersing the amorphous solid dispersion into a d-acetate buffer at pH 5.5 and 37 ░C. By virtue of MAS at 2.7 kHz, the extremely broad and unresolved 1H resonances of MFA in one-dimensional 1H NMR spectrum of the supersaturated solution are well resolved, thus enabling the complete assignment of MFA 1H resonances in the aqueous solution. Two-dimensional (2D) 1H/1H nuclear Overhauser effect spectroscopy (NOESY) and radio frequency-driven recoupling (RFDR) under MAS conditions reveal the interaction of MFA with EPO in the supersaturated solution at an atomic level. The strong cross-correlations observed in the 2D 1H/1H NMR spectra indicate a hydrophobic interaction between the aromatic group of MFA and the backbone of EPO. Furthermore, the aminoalkyl group in the side chain of EPO forms a hydrophilic interaction, which can be either electrostatic or hydrogen bonding, with the carboxyl group of MFA. We believe these hydrophobic and hydrophilic interactions between MFA and EPO molecules play a key role in the formation of this extremely stable supersaturated solution. In addition, 2D 1H/1H RFDR demonstrates that the molecular MFA-EPO interaction is quite flexible and dynamic. PMID:24283196
Chemical-shift-resolved ╣?F NMR spectroscopy between 13.5 and 135 MHz: Overhauser-DNP-enhanced diagonal suppressed correlation spectroscopy.
George, Christy; Chandrakumar, Narayanan
Overhauser-DNP-enhanced homonuclear 2D (19)F correlation spectroscopy with diagonal suppression is presented for small molecules in the solution state at moderate fields. Multi-frequency, multi-radical studies demonstrate that these relatively low-field experiments may be operated with sensitivity rivalling that of standard 200-1000?MHz NMR spectroscopy. Structural information is accessible without a sensitivity penalty, and diagonal suppressed 2D NMR correlations emerge despite the general lack of multiplet resolution in the 1D ODNP spectra. This powerful general approach avoids the rather stiff excitation, detection, and other special requirements of high-field (19)F?NMR spectroscopy. PMID:24962142
Probing electric fields in proteins in solution by NMR spectroscopy.
Hass, Mathias A S; Jensen, Malene Ringkj°bing; Led, Jens J
Electric fields generated in native proteins affect almost every aspect of protein function. We present a method that probes changes in the electric field at specific locations within a protein. The method utilizes the dependence of the amide (1)H and (15)N NMR chemical shifts on electric charges in proteins. Charges were introduced at different positions in the blue copper protein plastocyanin, by protonation of side chains or by substitution of the metal ion. It is found that the associated chemical shift perturbations (CSPs) stem mainly from long-range electric field effects caused by the change in the electric charge. It is demonstrated that the CSPs can be used to estimate the dielectric constant at different locations in the protein, estimate the nuclear shielding polarizability, or position charges in proteins. PMID:18214953
NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation
Richards, T.; Budinger, T.F.
NMR imaging, NMR spectroscopy, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the rodent brain after in vivo helium beam irradiation with single doses of 10, 20, 30, and 50 Gy. Two-dimensional Fourier transform spin-echo imaging and saturation recovery with projection reconstruction were used to measure the NMR relaxation parameters. These parameters were correlated with proton spectroscopy and histopathology. Additional high resolution in vitro proton spectroscopy was performed on brain extracts to observe chemical changes that could not be seen in vivo. The major findings from these experiments were that at 4-14 days postirradiation, image intensity and T1 relaxation time decreased on the irradiated side and increased on the nonirradiated side relative to nonirradiated control animals. In vivo surface coil proton spectroscopy methods demonstrated changes in lipid and phosphatidylcholine (p-choline) peaks. In vitro studies of the aqueous fraction of brain extracts showed radiation-induced changes in lactate, 4-aminobutyric acid, and p-choline peak areas. In the organic fraction, radiation-induced changes were observed in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. With histology and Evans blue injections, blood-brain barrier alterations were seen as early as 4 days after a dose of 50 Gy.
Metabolomic differentiation of Cannabis sativa cultivars using 1H NMR spectroscopy and principal component analysis.
Choi, Young Hae; Kim, Hye Kyong; Hazekamp, Arno; Erkelens, Cornelis; Lefeber, Alfons W M; Verpoorte, Robert
The metabolomic analysis of 12 Cannabis sativa cultivars was carried out by 1H NMR spectroscopy and multivariate analysis techniques. Principal component analysis (PCA) of the 1H NMR spectra showed a clear discrimination between those samples by principal component 1 (PC1) and principal component 3 (PC3) in cannabinoid fraction. The loading plot of PC value obtained from all 1)H NMR signals shows that Delta9-tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA) are important metabolites to differentiate the cultivars from each other. The discrimination of the cultivars could also be obtained from a water extract containing carbohydrates and amino acids. The level of sucrose, glucose, asparagine, and glutamic acid are found to be major discriminating metabolites of these cultivars. This method allows an efficient differentiation between cannabis cultivars without any prepurification steps. PMID:15217272
Target-Based Whole-Cell Screening by 1H?NMR Spectroscopy**
Ma, Junhe; Cao, Qing; McLeod, Sarah M; Ferguson, Keith; Gao, Ning; Breeze, Alexander L; Hu, Jun
An NMR-based approach marries the two traditional screening technologies (phenotypic and target-based screening) to find compounds inhibiting a specific enzymatic reaction in bacterial cells. Building on a previous study in which it was demonstrated that hydrolytic decomposition of meropenem in living Escherichia coli cells carrying New Delhi metallo-?-lactamase subclass 1 (NDM-1) can be monitored in real time by NMR spectroscopy, we designed a cell-based NMR screening platform. A strong NDM-1 inhibitor was identified with cellular IC50 of 0.51??m, which is over 300-fold more potent than captopril, a known NDM-1 inhibitor. This new screening approach has great potential to be applied to targets in other cell types, such as mammalian cells, and to targets that are only stable or functionally competent in the cellular environment. PMID:25693499
Orientational ordering studies of fluorinated thermotropic liquid crystals by NMR spectroscopy.
Calucci, Lucia; Geppi, Marco; Urban, Stanislaw
Fluorinated calamitic thermotropic liquid crystals represent an important class of materials for high-tech applications, especially in the field of liquid crystal displays. The investigation of orientational ordering in these systems is fundamental owing to the dependence of their applications on the anisotropic nature of macroscopic optical, dielectric, and visco-elastic properties. NMR spectroscopy is the most powerful technique for studying orientational order in liquid crystalline systems at a molecular level thanks to the possibility of exploiting different anisotropic observables (chemical shift, dipolar couplings, and quadrupolar coupling) and nuclei ((2)H, (13)C, and (19)F). In this paper, the basic theory and NMR experiments useful for the investigation of orientational order on fluorinated calamitic liquid crystals are reported, and a review of the literature published on this subject is given. Finally, orientational order parameters determined by NMR data are discussed in comparison to those obtained by optical and dielectric anisotropy measurements. PMID:25042970
Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy
Schwartz, D.J.
NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.
Perilla frutescens (L.) Britton: honeybee forage and preliminary results on the metabolic profiling by NMR spectroscopy.
Consonni, Roberto; Cagliani, Laura Ruth; Docimo, Teresa; Romane, Abderrahmane; Ferrazzi, Paola
Nuclear magnetic resonance (NMR) spectroscopy has emerged as a technology for metabolite characterisation of both foods and plants. NMR technique allows to analyse metabolite content in a single experiment, in a non-destructive way and with a very simple sample preparation. This study characterises the metabolites of Perilla frutescens var. crispa leaf and flower for the first time by NMR. Our results showed higher metabolite content in leaves compared to flowers, highlighting the presence of amino acids, organic acids, saccharides and large amounts of aromatic compounds, mainly in the form of rosmarinic acid. Moreover, we cultivated Perilla, an important medicinal plant native to Asia, in a low mountain environment in Italy, to continue its evaluation as a honeybee attractive species. Interestingly, even in this type of environment, Perilla has been confirmed to be a good bee plant for both nectar and pollen. PMID:23240606
Analytical 13 C NMR spectroscopy of fatty quaternary amines
E. H. Fairchild
Natural abundance13C nuclear magnetic resonance spectroscopy (CMR) has been used for the rapid, nondestructive analysis of fatty quaternary ammonium\\u000a compounds. Quantitative analysis of mixtures of mono-, di-and tri-fatty ammonium chlorides can be accommpublished under conditions\\u000a that do not involve heat or extremes of pH and that are independent of solvent present. In order to determine optimal conditions\\u000a for quantitative studies,
Magic angle spinning NMR spectroscopy: a versatile technique for structural and dynamic analysis of solid-phase systems.
Polenova, Tatyana; Gupta, Rupal; Goldbourt, Amir
Magic Angle Spinning (MAS) NMR spectroscopy is a powerful method for analysis of a broad range of systems, including inorganic materials, pharmaceuticals, and biomacromolecules. The recent developments in MAS NMR instrumentation and methodologies opened new vistas to atomic-level characterization of a plethora of chemical environments previously inaccessible to analysis, with unprecedented sensitivity and resolution. PMID:25794311
Quantification of human amniotic fluid constituents by high resolution proton nuclear magnetic resonance (NMR) spectroscopy.
Sims, C J; Fujito, D T; Burholt, D R; Dadok, J; Giles, H R; Wilkinson, D A
We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal alpha-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mM phosphate buffer and 6.02 mM disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were 'NMR visible' in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 microM. Good agreement with literature values based on other analytical techniques was obtained. PMID:8396770
Cis-trans isomerisation of azobenzenes studied by NMR spectroscopy with in situ laser irradiation and DFT calculationsĀ
Wazzan, Nuha
NMR spectroscopy with in situ laser irradiation has been used to investigate the photo- and thermal isomerisation of eight azobenzene derivatives; diphenyldiazene (azobenzene), p-phenylazoaniline (p-aminoazobenzene), 4-(dimethylamino...
Rapid quantitation of thermal oxidation products in fats and oils by 1H-NMR spectroscopy.
Yang, C M; Grey, A A; Archer, M C; Bruce, W R
This work describes the application of high-resolution proton nuclear magnetic resonance (1H-NMR) spectroscopy to the study of the thermal peroxidation of beef tallow and corn oil under standardized conditions. The approach provides a rapid, quantitative method for determining the degree of oxidation of unsaturated fatty acids in animal and vegetable fats and oils by quantitating the decreasing intensities of 1H-NMR peaks for allylic and olefinic protons in unsaturated fatty acid chains of triglycerides and the increasing peak intensities of hydroperoxide and saturated and alpha, beta-unsaturated aldehydic protons in relation to the less labile protons in the triglyceride molecule. Two-dimensional correlation spectroscopy analysis of highly oxidized beef tallow (180 degrees C for 24 h) suggested that the unsaturated aldehydes that persisted were apparently associated with carboxy groups. PMID:9507515
Facile backbone structure determination of human membrane proteins by NMR spectroscopy
Klammt, Christian; Maslennikov, Innokentiy; Bayrhuber, Monika; Eichmann, Cķdric; Vajpai, Navratna; Chiu, Ellis Jeremy Chua; Blain, Katherine Y; Esquivies, Luis; Kwon, June Hyun Jung; Balana, Bartosz; Pieper, Ursula; Sali, Andrej; Slesinger, Paul A; Kwiatkowski, Witek; Riek, Roland; Choe, Senyon
Although nearly half of todayÆs major pharmaceutical drugs target human integral membrane proteins (hIMPs), only 30 hIMP structures are currently available in the Protein Data Bank, largely owing to inefficiencies in protein production. Here we describe a strategy for the rapid structure determination of hIMPs, using solution NMR spectroscopy with systematically labeled proteins produced via cell-free expression. We report new backbone structures of six hIMPs, solved in only 18 months from 15 initial targets. Application of our protocols to an additional 135 hIMPs with molecular weight <30 kDa yielded 38 hIMPs suitable for structural characterization by solution NMR spectroscopy without additional optimization. PMID:22609626
Fundamental studies of supported bimetallic catalysts by NMR spectroscopy
Savargaonkar, N.
Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.
Broadband "infinite-speed" magic-angle spinning NMR spectroscopy.
Hu, Yan-Yan; Levin, E M; Schmidt-Rohr, Klaus
High-resolution magic-angle spinning NMR of high-Z spin-1/2 nuclei such as (125)Te, (207)Pb, (119)Sn, (113)Cd, and (195)Pt is often hampered by large (>1000 ppm) chemical-shift anisotropies, which result in strong spinning sidebands that can obscure the centerbands of interest. In various tellurides with applications as thermoelectrics and as phase-change materials for data storage, even 22-kHz magic-angle spinning cannot resolve the center- and sidebands broadened by chemical-shift dispersion, which precludes peak identification or quantification. For sideband suppression over the necessary wide spectral range (up to 200 kHz), radio frequency pulse sequences with few, short pulses are required. We have identified Gan's two-dimensional magic-angle-turning (MAT) experiment with five 90 degrees pulses as a promising broadband technique for obtaining spectra without sidebands. We have adapted it to broad spectra and fast magic-angle spinning by accounting for long pulses (comparable to the dwell time in t(1)) and short rotation periods. Spectral distortions are small and residual sidebands negligible even for spectra with signals covering a range of 1.5 gammaB(1), due to a favorable disposition of the narrow ranges containing the signals of interest in the spectral plane. The method is demonstrated on various technologically interesting tellurides with spectra spanning up to 170 kHz, at 22 kHz MAS. PMID:19489580
Structural Studies of Biomaterials Using Double-Quantum Solid-State NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Drobny, G. P.; Long, J. R.; Karlsson, T.; Shaw, W.; Popham, J.; Oyler, N.; Bower, P.; Stringer, J.; Gregory, D.; Mehta, M.; Stayton, P. S.
Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composites technologies. Here, we describe both the theory and practice of double-quantum solid-state NMR (ssNMR) structure-determination techniques, as they are used to determine the secondary structures of surface-adsorbed peptides and proteins. In particular, we have used ssNMR dipolar techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxyapatite (HAP) surface. Here, we also review NMR data on peptides designed to adsorb from aqueous solutions onto highly porous hydrophobic surfaces with specific helical secondary structures. The adsorption or covalent attachment of biological macromolecules onto polymer materials to improve their biocompatibility has been pursued using a variety of approaches, but key to understanding their efficacy is the verification of the structure and dynamics of the immobilized biomolecules using double-quantum ssNMR spectroscopy.
Monitoring the Electrochemical Processes in the Lithium¢Air Battery by Solid State NMR Spectroscopy
A multi-nuclear solid-state NMR approach is employed to investigate the lithium¢air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13C ssNMR provides evidence for carbonate formation on the surface of the carbon cathode, the carbonate being removed at high charging voltages in the first cycle, but accumulating in later cycles. Small amounts of lithium hydroxide and formate are also detected in discharged cathodes and while the hydroxide formation is reversible, the formate persists and accumulates in the cathode upon further cycling. The results indicate that the rechargeability of the battery is limited by both the electrolyte and the carbon cathode stability. The utility of ssNMR spectroscopy in directly detecting product formation and decomposition within the battery is demonstrated, a necessary step in the assessment of new electrolytes, catalysts, and cathode materials for the development of a viable lithium¢oxygen battery. PMID:24489976
Analytical Expressions for the b Matrix in NMR Diffusion Imaging and Spectroscopy
NASA Astrophysics Data System (ADS)
Mattiello, J.; Basser, P. J.; Lebihan, D.
General analytical expressions are presented for the b matrix used in diffusion NMR imaging and spectroscopy. These expressions are evaluated in the case of a two-dimensional Fourier-transform spin-echo imaging sequence and show the effect of "cross terms" between gradient pulses. The diagonal and off-diagonal components of the b matrix are calculated for the anisotropic diffusion tenser. The proposed analysis allows diffusion coefficients and tensors to be determined accurately and with greater efficiency.
Locust flight metabolism studied in vivo by 31 P NMR spectroscopy
Gerhard Wegener; Nicholas M. Bolas; Andrķ A. G. Thomas
Flight metabolism of locusts has been extensively studied, but biochemical and physiological methods have led to conflicting results. For this reason the non-invasive and non-destructive method of 31P NMR spectroscopy was used to study migratory locusts, Locusta migratoria, at rest and during flight.1.In the flight muscle of resting locusts the ratio of phosphoarginine to ATP was the same whether determined
Gyrotron FU CW VII for 300 MHz and 600 MHz DNP-NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Idehara, Toshitaka; Kosuga, Kosuke; Agusu, La; Ogawa, Isamu; Takahashi, Hiroki; Smith, Mark E.; Dupree, Ray
Gyrotron FU CW VII, one of the FU CW Series Gyrotrons, has been designed, constructed and completed operational tests successfully in the Research Center for Development of Far Infrared Region, University of Fukui (FIR FU). The gyrotron operates at around 200 GHz for the fundamental cyclotron resonances and at around 400 GHz for the second harmonics. These radiation frequencies will be applied to 300 MHz and 600 MHz DNP enhanced NMR spectroscopy.
Two-dimensional 2 H NMR exchange spectroscopy on conducting ionic crystals
J. Totzt; D. Michel; Yu. N. Ivanov; I. P. Aleksandrova; J. Petersson; A. Kl÷pperpieper
The two-dimensional (2-D) deuterium nuclear magnetic resonance (NMR) exchange spectroscopy is applied to two types of conducting\\u000a ionic crystals for the study of hydrogen mobility and conductivity, viz. partially deuterated ammonium hydrogen selenate,\\u000a NH4HSO4 (AHSe), and partially deuterated mixed crystals of betaine phosphate (DBP) and betaine phosphite (DBPI), DBP1?x\\u000a DBPIx. In both crystals chemical exchange processes of deuterons between different
Analysis of epoxy resin formulations by ┬╣┬│C NMR spectroscopy
R. A. Assink; F. T. Gurule
The chloroform soluble components of several epoxy resin formulations were analyzed by ┬╣┬│C NMR spectroscopy. The technique permits the components of an epoxy resin formulation to be identified on a routine basis with a high degree of confidence. Narmco's 5208 contained MY-720 and EpiRez SU-7 or SU-8. Two versions of Ferro's CE-9000 contained ERL-0510 and EpiRez SU-7 or SU-8. Although
Structural Transitions in Short-Chain Lipid Assemblies Studied by 31P-NMR Spectroscopy
J÷rg H. Kleinschmidt; Lukas K. Tamm
The self-assembled supramolecular structures of diacylphosphatidylcholine (diCnPC), diacylphosphatidylethanolamine (diCnPE), diacylphosphatidyglycerol (diCnPG), and diacylphosphatidylserine (diCnPS) were investigated by 31P nuclear magnetic resonance (NMR) spectroscopy as a function of the hydrophobic acyl chain length. Short-chain homologs of these lipids formed micelles, and longer-chain homologs formed bilayers. The shortest acyl chain lengths that supported bilayer structures depended on the headgroup of the lipids.
Intracellular Free Calcium Concentration Measured with 19F NMR Spectroscopy in Intact Ferret Hearts
Eduardo Marban; Masafumi Kitakaze; Hideo Kusuoka; James K. Porterfield; David T. Yue; V. P. Chacko
Changes in the intracellular free Ca2+ concentration, [Ca2+]i, mediate excitation-contraction coupling in the heart and contribute to cellular injury during ischemia and reperfusion. To study these processes directly, we measured [Ca2+]i in perfused ferret (Mustela putorius furo) hearts using 19F NMR spectroscopy to detect the 5,5'-difluoro derivative of the Ca2+ chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'- tetraacetic acid (BAPTA). To load cells, hearts were
Nanotechnology for biomaterials engineering: structural characterization of amphiphilic polymeric nanoparticles by 1H NMR spectroscopy
Jeffrey S. Hrkach; Maria Teresa Peracchia; Avi Bomb; noah Lotan; Robert Langer
Nanoparticles composed of diblock poly(d,l-lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG) or a branched, multiblock PLA-(PEG)3 were prepared by the single emulsion technique. Results of previous studies of these nanoparticles suggested that their structure is of the core-corona type with a polyester core and an outer PEG coating. In the present study, 1H NMR spectroscopy was utilized to provide direct evidence of the structure
Bernhard Bl³mich; Federico Casanova; Ernesto Danieli; Qingxia Gong; Marcus Greferath; Agnes Haber; J³rgen Kolz; Juan Perlo
Initiated by the use of NMR for well logging, portable NMR instruments are being developed for a variety of novel applications in materials testing and process analysis and control. Open sensors enable non-destructive testing of large objects, and small, cup-size magnets become available for high throughput analysis by NMR relaxation and spectroscopy. Some recent developments of mobile NMR are reviewed
Insights into reaction mechanisms in heterogeneous catalysis revealed by in situ NMR spectroscopy.
Blasco, Teresa
This tutorial review intends to show the possibilities of in situ solid state NMR spectroscopy in the elucidation of reaction mechanisms and the nature of the active sites in heterogeneous catalysis. After a brief overview of the more usual experimental devices used for in situ solid state NMR spectroscopy measurements, some examples of applications taken from the recent literature will be presented. It will be shown that in situ NMR spectroscopy allows: (i) the identification of stable intermediates and transient species using indirect methods, (ii) to prove shape selectivity in zeolites, (iii) the study of reaction kinetics, and (iv) the determination of the nature and the role played by the active sites in a catalytic reaction. The approaches and methodology used to get this information will be illustrated here summarizing the most relevant contributions on the investigation of the mechanisms of a series of reactions of industrial interest: aromatization of alkanes on bifunctional catalysts, carbonylation reaction of methanol with carbon monoxide, ethylbenzene disproportionation, and the Beckmann rearrangement reaction. Special attention is paid to the research carried out on the role played by carbenium ions and alkoxy as intermediate species in the transformation of hydrocarbon molecules on solid acid catalysts. PMID:20976339
Phase-alternated composite pulses for zero-field NMR spectroscopy of spin 1 systems
NASA Astrophysics Data System (ADS)
Ramamoorthy, A.
A set of composite pulses is described that compensates the effects of electric field gradient (EFG) inhomogeneity and resonance offset for zero-field NMR spectroscopy of a single crystal specimen containing physically equivalent spin 1 nuclei. These sequences are designed using the Magnus expansion approach. The phases of the RF pulses in the sequence are restricted to 0 and 180 only. The phase restriction drastically reduces the complexity and computation time involved in the numerical search of composite pulses via the Magnus expansion method. The derivation of phase-alternating composite pulses and the computer simulations which describe their performance against offset and EFG inhomogeneity effects are presented. It is inferred that the performance of these composite pulses is symmetric with respect to the sign of the offset and independent of asymmetry in EFG tensor. Based on these, a 45 135, composite pi/2 pulse, and a 315 225 90, broadband population inversion pulse, are proposed for the zero-field NMR spectroscopy of solids. Composite pulses reported here are applicable also to the high field NMR spectroscopy of spin 1 nuclei.
Three-dimensional solution structure of Cucurbita maxima trypsin inhibitor-V determined by NMR spectroscopy.
Cai, M; Gong, Y; Kao, J L; Krishnamoorthi, R
The solution structure of Cucurbita maxima trypsin inhibitor-V (CMTI-V), which is also a specific inhibitor of the blood coagulation protein, factor XIIa, was determined by 1H NMR spectroscopy in combination with a distance-geometry and simulated annealing algorithm. Sequence-specific resonance assignments were made for all the main-chain and most of the side-chain hydrogens. Stereospecific assignments were also made for some of the beta-, gamma-, delta-, and epsilon-hydrogens and valine methyl hydrogens. The ring conformations of all six prolines in the inhibitor were determined on the basis of 1H-1H vicinal coupling constant patterns; most of the proline ring hydrogens were stereospecifically assigned on the basis of vicinal coupling constant and intraresidue nuclear Overhauser effect (NOE) patterns. Distance constraints were determined on the basis of NOEs between pairs of hydrogens. Dihedral angle constraints were determined from estimates of scalar coupling constants and intraresidue NOEs. On the basis of 727 interproton distance and 111 torsion angle constraints, which included backbone phi angles and side-chain chi 1, chi 2, chi 3, and chi 4 angles, 22 structures were calculated by a distance geometry algorithm and refined by energy minimization and simulated annealing methods. Both main-chain and side-chain atoms are well-defined, except for a loop region, two terminal residues, and some side-chain atoms located on the molecular surface. The average root mean squared deviation in the position for equivalent atoms between the 22 individual structures and the mean structure obtained by averaging their coordinates is 0.58 +/- 0.06 A for the main-chain atoms and 1.01 +/- 0.07 A for all the non-hydrogen atoms of residues 3-40 and 49-67. These structures were compared to the X-ray crystallographic structure of another protein of the same inhibitor family-chymotrypsin inhibitor-2 from barley seeds [CI-2; McPhalen, C. A., & James, M. N. G. (1987) Biochemistry 26, 261-269]. The main-chain folding patterns are highly similar for the two proteins, which possess 62% sequence differences. However, major differences are noted in the N- and C-terminal segments, which may be due to the presence of a disulfide bridge in CMTI-V, but not in CI-2. PMID:7711040
Nuclear charge-distribution effects on the NMR spectroscopy parameters
NASA Astrophysics Data System (ADS)
Maldonado, Alejandro F.; Gimķnez, Carlos A.; Aucar, Gustavo A.
We present here a systematic study about the influence of the size and type of nuclear charge-distribution models (Gaussian and point-like) on the NMR spectroscopic parameters, the nuclear magnetic shielding ? and the indirect nuclear spin J-coupling. We found that relativistic effects largely enhance the nuclear charge-distribution effects (NChDE) on those parameters being them quite sensitive to the nuclear model adopted for calculations. Results for two rare gas atoms (Kr, Rn) and few molecular systems like HX, (X = Br, I, At), CH4, SnH4, SnIH3, SnI2H2, and PbIH3 are presented. J-couplings are more sensitive than shieldings in both, relativistic and non-relativistic (NR) regimes. The highest effect (close to 11% of variation in relativistic calculations with that two different nuclear models) is observed for J(Pb-I) in PbIH3. A similar effect is found for J(Pb-H) in the same molecule, close to 9%. The NChDE for ?(Sn) in SnI4-nHn with n = 1, 2 is as large as few ppm (between 3 and 8.56 ppm). For J(Sn-H) in this set of molecules, it goes from 37 Hz for SnH4 to 54 Hz for SnI2H2. Furthermore, we found that the vicinal NChDE is very small though not zero. For 1J(Sn-H) in SnIH3, the NChDE of iodine is close to 2 Hz (0.1%). We also studied the NChDE on the ground state electronic energies of atoms and molecules. We found that these effects are only important within the relativistic regime but not within the NR one. They are in good agreement with previous works.
HRMAS-NMR spectroscopy and multivariate analysis meat characterisation.
Ritota, Mena; Casciani, Lorena; Failla, Sebastiana; Valentini, Massimiliano
╣H-High resolution magic angle spinning-nuclear magnetic resonance spectroscopy was employed to gain the metabolic profile of longissimus dorsi and semitendinosus muscles of four different breeds: Chianina, Holstein Friesian, Maremmana and Buffalo. Principal component analysis, partial least squares projection to latent structure - discriminant analysis and orthogonal partial least squares projection to latent structure - discriminant analysis were used to build models capable of discriminating the muscle type according to the breed. Data analysis led to an excellent classification for Buffalo and Chianina, while for Holstein Friesian the separation was lower. In the case of Maremmana the use of intelligent bucketing was necessary due to some resonances shifting allowed improvement of the discrimination ability. Finally, by using the Variable Importance in Projection values the metabolites relevant for the classification were identified. PMID:22819725
Structural basis of the green-blue color switching in proteorhodopsin as determined by NMR spectroscopy.
Mao, Jiafei; Do, Nhu-Nguyen; Scholz, Frank; Reggie, Lenica; Mehler, Michaela; Lakatos, Andrea; Ong, Yean-Sin; Ullrich, Sandra J; Brown, Lynda J; Brown, Richard C D; Becker-Baldus, Johanna; Wachtveitl, Josef; Glaubitz, Clemens
Proteorhodopsins (PRs) found in marine microbes are the most abundant retinal-based photoreceptors on this planet. PR variants show high levels of environmental adaptation, as their colors are tuned to the optimal wavelength of available light. The two major green and blue subfamilies can be interconverted through a L/Q point mutation at position 105. Here we reveal the structural basis behind this intriguing color-tuning effect. High-field solid-state NMR spectroscopy was used to visualize structural changes within green PR directly within the lipid bilayer upon introduction of the green-blue L105Q mutation. The observed effects are localized within the binding pocket and close to retinal carbons C14 and C15. Subsequently, magic-angle spinning (MAS) NMR spectroscopy with sensitivity enhancement by dynamic nuclear polarization (DNP) was applied to determine precisely the retinal structure around C14-C15. Upon mutation, a significantly stretched C14-C15 bond, deshielding of C15, and a slight alteration of the retinal chain's out-of-plane twist was observed. The L105Q blue switch therefore acts locally on the retinal itself and induces a conjugation defect between the isomerization region and the imine linkage. Consequently, the S0-S1 energy gap increases, resulting in the observed blue shift. The distortion of the chromophore structure also offers an explanation for the elongated primary reaction detected by pump-probe spectroscopy, while chemical shift perturbations within the protein can be linked to the elongation of late-photocycle intermediates studied by flash photolysis. Besides resolving a long-standing problem, this study also demonstrates that the combination of data obtained from high-field and DNP-enhanced MAS NMR spectroscopy together with time-resolved optical spectroscopy enables powerful synergies for in-depth functional studies of membrane proteins. PMID:25415762
Stereochemistry of 16a-hydroxyfriedelin and 3-Oxo-16-methylfriedel-16-ene established by 2D NMR spectroscopy.
Duarte, Lucienir Pains; Silva de Miranda, Roqueline Rodrigues; Rodrigues, SalomŃo Bento Vasconcelos; de Fßtima Silva, Grßcia Divina; Vieira Filho, Sidney Augusto; Knupp, Vagner Fernandes
Friedelin (1), 3beta-friedelinol (2), 28-hydroxyfriedelin (3), 16alpha-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16alpha,28-dihydroxyfriedelin (6) were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl(3) solution, 16alpha-hydroxyfriedelin (4) reacted turning into 3-oxo-16-methylfriedel-16-ene (7). This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl(3) solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY) spectroscopy and mass spectrometry (GC-MS). It is also the first time that all the (13)C-NMR and 2D NMR spectral data are reported for compounds 4 and 7. PMID:19214150
NMR-based approach to the analysis of radiopharmaceuticals: radiochemical purity, specific activity, and radioactive concentration values by proton and tritium NMR spectroscopy.
Schenk, David J; Dormer, Peter G; Hesk, David; Pollack, Scott R; Lavey, Carolee Flader
Compounds containing tritium are widely used across the drug discovery and development landscape. These materials are widely utilized because they can be efficiently synthesized and produced at high specific activity. Results from internally calibrated (3) H and (1) H nuclear magnetic resonance (NMR) spectroscopy suggests that at least in some cases, this calibrated approach could supplement or potentially replace radio-high-performance liquid chromatography for radiochemical purity, dilution and scintillation counting for the measurement of radioactivity per volume, and liquid chromatography/mass spectrometry analysis for the determination of specific activity. In summary, the NMR-derived values agreed with those from the standard approaches to within 1% to 9% for solution count and specific activity. Additionally, the NMR-derived values for radiochemical purity deviated by less than 5%. A benefit of this method is that these values may be calculated at the same time that (3) H NMR analysis provides the location and distribution of tritium atoms within the molecule. Presented and discussed here is the application of this method, advantages and disadvantages of the approach, and a rationale for utilizing internally calibrated (1) H and (3) H NMR spectroscopy for specific activity, radioactive concentration, and radiochemical purity whenever acquiring (3) H NMR for tritium location. PMID:26014438
Lithium ion diffusion in Li ?-alumina single crystals measured by pulsed field gradient NMR spectroscopy
Chowdhury, Mohammed Tareque, E-mail: email@example.com; Takekawa, Reiji; Iwai, Yoshiki; Kuwata, Naoaki; Kawamura, Junichi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai 980-8577 (Japan)] [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai 980-8577 (Japan)
The lithium ion diffusion coefficient of a 93% Li ?-alumina single crystal was measured for the first time using pulsed field gradient (PFG) NMR spectroscopy with two different crystal orientations. The diffusion coefficient was found to be 1.2 ū 10{sup ?11} m{sup 2}/s in the direction perpendicular to the c axis at room temperature. The Li ion diffusion coefficient along the c axis direction was found to be very small (6.4 ū 10{sup ?13} m{sup 2}/s at 333 K), which suggests that the macroscopic diffusion of the Li ion in the ?-alumina crystal is mainly two-dimensional. The diffusion coefficient for the same sample was also estimated using NMR line narrowing data and impedance measurements. The impedance data show reasonable agreement with PFG-NMR data, while the line narrowing measurements provided a lower value for the diffusion coefficient. Line narrowing measurements also provided a relatively low value for the activation energy and pre-exponential factor. The temperature dependent diffusion coefficient was obtained in the temperature range 297¢333 K by PFG-NMR, from which the activation energy for diffusion of the Li ion was estimated. The activation energy obtained by PFG-NMR was smaller than that obtained by impedance measurements, which suggests that thermally activated defect formation energy exists for 93% Li ?-alumina single crystals. The diffusion time dependence of the diffusion coefficient was observed for the Li ion in the 93% Li ?-alumina single crystal by means of PFG-NMR experiments. Motion of Li ion in fractal dimension might be a possible explanation for the observed diffusion time dependence of the diffusion coefficient in the 93% Li ?¢alumina system.
Identifying metabolites related to nitrogen mineralisation using 1H NMR spectroscopy
NASA Astrophysics Data System (ADS)
. T McDonald, Noeleen; Graham, Stewart; Watson, Catherine; Gordon, Alan; Lalor, Stan; Laughlin, Ronnie; Elliott, Chris; . P Wall, David
Exploring new analysis techniques to enhance our knowledge of the various metabolites within our soil systems is imperative. Principally, this knowledge would allow us to link key metabolites with functional influences on critical nutrient processes, such as the nitrogen (N) mineralisation in soils. Currently there are few studies that utilize proton nuclear magnetic resonance spectroscopy (1H NMR) to characterize multiple metabolites within a soil sample. The aim of this research study was to examine the effectiveness of 1H NMR for isolating multiple metabolites that are related to the mineralizable N (MN) capacity across a range of 35 Irish grassland soils. Soils were measured for MN using the standard seven day anaerobic incubation (AI-7). Additionally, soils were also analysed for a range of physio-chemical properties [e.g. total N, total C, mineral N, texture and soil organic matter (SOM)]. Proton NMR analysis was carried on these soils by extracting with 40% methanol:water, lyophilizing and reconstituting in deuterium oxide and recording the NMR spectra on a 400MHz Bruker AVANCE III spectrometer. Once the NMR data were spectrally processed and analysed using multivariate statistical analysis, seven metabolites were identified as having significant relationships with MN (glucose, trimethylamine, glutamic acid, serine, aspartic acid, 4-aminohippuirc acid and citric acid). Following quantification, glucose was shown to explain the largest percentage variability in MN (72%). These outcomes suggest that sources of labile carbon are essential in regulating N mineralisation and the capacity of plant available N derived from SOM-N pools in these soils. Although, smaller in concentration, the amino acids; 4-aminohippuirc acid, glutamic acid and serine also significantly (P<0.05) explained 43%, 27% and 19% of the variability in MN, respectively. This novel study highlights the effectiveness of using 1H NMR as a practical approach to profile multiple metabolites in soils simultaneously, and increasing the potential to identify those related to various soil processes.
Novel monosaccharide fermentation products in Caldicellulosiruptor saccharolyticus identified using NMR spectroscopy
Background Caldicellulosiruptor saccharolyticus is a thermophilic, Gram-positive, non-spore forming, strictly anaerobic bacterium of interest in potential industrial applications, including the production of biofuels such as hydrogen or ethanol from lignocellulosic biomass through fermentation. High-resolution, solution-state nuclear magnetic resonance (NMR) spectroscopy is a useful method for the identification and quantification of metabolites that result from growth on different substrates. NMR allows facile resolution of isomeric (identical mass) constituents and does not destroy the sample. Results Profiles of metabolites produced by the thermophilic cellulose-degrading bacterium Caldicellulosiruptor saccharolyticus DSM 8903 strain following growth on different monosaccharides (D-glucose, D-mannose, L-arabinose, D-arabinose, D-xylose, L-fucose, and D-fucose) as carbon sources revealed several unexpected fermentation products, suggesting novel metabolic capacities and unexplored metabolic pathways in this organism. Both 1H and 13C nuclear magnetic resonance (NMR) spectroscopy were used to determine intracellular and extracellular metabolite profiles. One dimensional 1H NMR spectral analysis was performed by curve fitting against spectral libraries provided in the Chenomx software; 2-D homonuclear and heteronuclear NMR experiments were conducted to further reduce uncertainties due to unassigned, overlapping, or poorly-resolved peaks. In addition to expected metabolites such as acetate, lactate, glycerol, and ethanol, several novel fermentation products were identified: ethylene glycol (from growth on D-arabinose), acetoin and 2,3-butanediol (from growth on D-glucose, L-arabinose, and D-xylose), and hydroxyacetone (from growth on D-mannose, L-arabinose, and D-xylose). Production of ethylene glycol from D-arabinose was particularly notable, with around 10% of the substrate carbon converted into this uncommon fermentation product. Conclusions The present research shows that C. saccharolyticus, already of substantial interest due to its capability for biological ethanol and hydrogen production, has further metabolic potential for production of higher molecular weight compounds, such as acetoin and 2,3-butanediol, as well as hydroxyacetone and the uncommon fermentation product ethylene glycol. In addition, application of nuclear magnetic resonance (NMR) spectroscopy facilitates identification of novel metabolites, which is instrumental for production of desirable bioproducts from biomass through microbial fermentation. PMID:23552326
High resolution sup 27 Al NMR spectroscopy of the aluminophosphate molecular sieve VPI-5
Wu, Y.; Chmelka, B.F.; Pines, A. (Lawrence Berkeley Lab., CA (United States)); Davis, M.E. (State Univ., Blacksburg, VA (United States)); Grobet, P.J.; Jacobs, P.A. (Catholic Univ. of Leuven (Belgium))
Aluminium plays an important part in determining the properties of many materials, such as the catalytic behavior of zeolites. Aluminophosphate molecular sieves, in particular, have useful applications as superlattice hosts in the fabrication of quantum-effect devices. Although nuclear magnetic resonance (NMR) spectroscopy is often a sensitive probe of solids, the use of {sup 27}Al NMR to investigate the structure of aluminosilicates and aluminophosphates has been severely limited because anisotropic second-order quadrupolar interactions, responsible for spectral broadening, cannot be eliminated by conventional magic-angle-spinning or multiple-pulse techniques. Here the authors report the first high-resolution NMR spectra of {sup 27}Al in a solid using double rotation and demonstrate its usefulness for probing subtle structural perturbations in the aluminophosphate molecular sieve VPI-5. From their results, they conclude that high-resolution {sup 27}Al NMR is capable of resolving discrete framework aluminium sites, permitting quantitative investigation of site-specific adsorbate interactions with the VPI-5 host.
Characterisation of germinating and non-germinating wheat seeds by nuclear magnetic resonance (NMR) spectroscopy.
Krishnan, P; Joshi, D K; Nagarajan, Shantha; Moharir, A V
Experiments were conducted to characterise the changes, especially of water status in germinating and non-germinating wheat seeds by nuclear magnetic resonance (NMR) spectroscopy. NMR relaxation time ( T(2)) measurements showed tri-phasic or bi-phasic characteristics during different stages of hydration, depending on the seed's ability to germinate. Component analysis of T(2) data revealed the existence of only two components, bound and bulk water, in dry seeds. In contrast, both the germinating and non-germinating wheat seeds had a three-component water proton system (bound, bulk and free water) in phase I of hydration. During the lag phase (phase II) of hydration, bulk water component of non-germinating seeds disappeared completely, resulting in a two component water proton system. Nevertheless, the three component water proton system was observed in the germinating seeds in phase II. Following phase II, rapid hydration (phase III) was observed in germinating seeds only. Water protons were re-organised and there were increases in bulk and free water but decreases in bound water concomitantly. Comparison of the physical state of water in these seeds by NMR spectroscopy with that of tissue leachate conductivity measurement suggests that the seed membrane system was affected more evidently in non-germinating seeds, leading to the disorganised cell structure. The present study provides evidence that the reorganisation of physical state of water in germinating wheat seeds during hydration is essential for its subsequent event of germination. PMID:12904911
Mapping Inhibitor Binding Modes on an Active Cysteine Protease via NMR Spectroscopy
Lee, Gregory M.; Balouch, Eaman; Goetz, David H.; Lazic, Ana; McKerrow, James H.; Craik, Charles S.
Cruzain is a member of the papain/cathepsin-L family of cysteine proteases, and the major cysteine protease of the protozoan Trypanosoma cruzi, the causative agent of ChagasÆ disease. We report an auto-induction methodology that provides soluble-cruzain at high yields (> 30 mg per liter in minimal media). These increased yields provide sufficient quantities of active enzyme for use in NMR-based ligand mapping. Using CD and NMR spectroscopy, we also examined the solution-state structural dynamics of the enzyme in complex with a covalently bound vinyl sulfone inhibitor (K777). We report the backbone amide and side chain carbon chemical shift assignments of cruzain in complex with K777. These resonance assignments were used to identify and map residues located in the substrate binding pocket, including the catalytic Cys25 and His162. Selective 15N-Cys, 15N-His, and 13C-Met labeling was performed to quickly assess cruzain-ligand interactions for a set of eight low molecular weight compounds exhibiting micromolar binding or inhibition. Chemical shift perturbation mapping verifies that six of the eight compounds bind to cruzain at the active site. Three different binding modes were delineated for the compounds, namely covalent, non-covalent, and non-interacting. These results provide examples of how NMR spectroscopy can be used to screen compounds for fast evaluation of enzyme-inhibitor interactions in order to facilitate lead compound identification and subsequent structural studies. PMID:23181936
Design and application of robust rf pulses for toroid cavity NMR spectroscopy
Thomas E. Skinner; Michael Braun; Klaus Woelk; Naum I. Gershenzon; Steffen J. Glaser
We present robust radio frequency (rf) pulses that tolerate a factor of six inhomogeneity in the B1 field, significantly enhancing the potential of toroid cavity resonators for NMR spectroscopic applications. Both point-to-point (PP) and unitary rotation (UR) pulses were optimized for excitation, inversion, and refocusing using the gradient ascent pulse engineering (GRAPE) algorithm based on optimal control theory. In addition, the optimized parameterization (OP) algorithm applied to the adiabatic BIR-4 UR pulse scheme enabled ultra-short (50 microsec) pulses with acceptable performance compared to standard implementations. OP also discovered a new class of non-adiabatic pulse shapes with improved performance within the BIR-4 framework. However, none of the OP-BIR4 pulses are competitive with the more generally optimized UR pulses. The advantages of the new pulses are demonstrated in simulations and experiments. In particular, the DQF COSY result presented here represents the first implementation of 2D NMR spectroscopy using a toroid probe.
Detoxification of organophosphorus pesticides and nerve agents through RSDL: efficacy evaluation by (31)P NMR spectroscopy.
Elsinghorst, Paul W; Worek, Franz; Koller, Marianne
Intoxication by organophosphorus compounds, especially by pesticides, poses a considerable risk to the affected individual. Countermeasures involve both medical intervention by means of antidotes as well as external decontamination to reduce the risk of dermal absorption. One of the few decontamination options available is Reactive Skin Decontamination Lotion (RSDL), which was originally developed for military use. Here, we present a (31)P NMR spectroscopy based methodology to evaluate the detoxification efficacy of RSDL with respect to a series of organophosphorus pesticides and nerve agents. Kinetic analysis of the obtained NMR data provided degradation half-lives proving that RSDL is also reasonably effective against organophosphorus pesticides. Unexpected observations of different RSDL degradation patterns are presented in view of its reported oximate-catalyzed mechanism of action. PMID:25597861
An instrument control and data analysis program for NMR imaging and spectroscopy
Roos, M.S.; Mushlin, R.A.; Veklerov, E.; Port, J.D.; Ladd, C.; Harrison, C.G.
We describe a software environment created to support real-time instrument control and signal acquisition as well as array-processor based signal and image processing in up to five dimensions. The environment is configured for NMR imaging and in vivo spectroscopy. It is designed to provide flexible tools for implementing novel NMR experiments in the research laboratory. Data acquisition and processing operations are programmed in macros which are loaded in assembled from to minimize instruction overhead. Data arrays are dynamically allocated for efficient use of memory and can be mapped directly into disk files. The command set includes primitives for real-time control of data acquisition, scalar arithmetic, string manipulation, branching, a file system and vector operations carried out by an array processor. 6 figs.
Application of /sup 31/P-NMR spectroscopy to the study of striated muscle metabolism
Meyer, R.A.; Kushmerick, M.J.; Brown, T.R.
This review presents the principles and limitations of phosphorus nuclear magnetic resonance (/sup 31/P-NMR) spectroscopy as applied to the study of striated muscle metabolism. Application of the techniques discussed include noninvasive measurement of high-energy phosphate, intracellular pH, intracellular free Mg/sup 2 +/, and metabolite compartmentation. In perfused cat biceps (fast-twitch) muscles, but not in soleus (slow-twitch), NMR spectra indicate a substantially lower (1 mM) free inorganic phosphate level than when measured chemically (6 mM). In addition, saturation and inversion spin-transfer methods that enable direct measurement of the unidirectional fluxes through creatine kinase are described. In perfused cat biceps muscle, results suggest that this enzyme and its substrates are in simple chemical equilibrium.
A dynamic nuclear polarization strategy for multi-dimensional Earth's field NMR spectroscopy.
Halse, Meghan E; Callaghan, Paul T
Dynamic nuclear polarization (DNP) is introduced as a powerful tool for polarization enhancement in multi-dimensional Earth's field NMR spectroscopy. Maximum polarization enhancements, relative to thermal equilibrium in the Earth's magnetic field, are calculated theoretically and compared to the more traditional prepolarization approach for NMR sensitivity enhancement at ultra-low fields. Signal enhancement factors on the order of 3000 are demonstrated experimentally using DNP with a nitroxide free radical, TEMPO, which contains an unpaired electron which is strongly coupled to a neighboring (14)N nucleus via the hyperfine interaction. A high-quality 2D (19)F-(1)H COSY spectrum acquired in the Earth's magnetic field with DNP enhancement is presented and compared to simulation. PMID:18926746
Microfabricated Inserts for Magic Angle Coil Spinning (MACS) Wireless NMR Spectroscopy
Badilita, Vlad; Fassbender, Birgit; Kratt, Kai; Wong, Alan; Bonhomme, Christian; Sakellariou, Dimitris; Korvink, Jan G.; Wallrabe, Ulrike
This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS) NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i) reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii) improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the ōmagic angleö of 54.74░ with respect to the direction of the magnetic field (magic angle spinning ¢ MAS), accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii) given the high spinning rates (tens of kHz) involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz) testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds. PMID:22936994
Arrangement and mobility of water in vermiculite hydrates followed by 1H NMR spectroscopy.
Sanz, J; Herrero, C P; Serratosa, J M
The arrangement of water molecules in one- and two-layer hydrates of high-charged vermiculites, saturated with alkaline (Li(+), Na(+)) and alkali-earth (Mg(2+), Ca(2+), Ba(2+)) cations, has been analyzed with (1)H NMR spectroscopy. Two different orientations for water molecules have been found, depending on the hydration state and the sites occupied by interlayer cations. As the amount of water increases, hydrogen bond interactions between water molecules increase at expenses of water-silicate interactions. This interaction favors water mobility in vermiculites. A comparison of the temperature dependence of relaxation times T(1) and T(2) for one and two-layer hydrates of Na-vermiculite shows that the rotations of water molecules around C(2)-axes and that of cation hydration shells around the c-axis is favored in the two-layer hydrate. In both hydrates, the anisotropic diffusion of water takes place at room temperature, preserving the orientation of water molecules relative to the silicate layers. Information obtained by NMR spectroscopy is compatible with that deduced by infrared spectroscopy and with structural studies carried out with X-ray and neutron diffraction techniques on single-crystals of vermiculite. PMID:16610877
Protein structure determination by high-resolution solid-state NMR spectroscopy: application to microcrystalline ubiquitin.
Zech, Stephan G; Wand, A Joshua; McDermott, Ann E
High-resolution solid-state NMR spectroscopy has become a promising method for the determination of three-dimensional protein structures for systems which are difficult to crystallize or exhibit low solubility. Here we describe the structure determination of microcrystalline ubiquitin using 2D (13)C-(13)C correlation spectroscopy under magic angle spinning conditions. High-resolution (13)C spectra have been acquired from hydrated microcrystals of site-directed (13)C-enriched ubiquitin. Inter-residue carbon-carbon distance constraints defining the global protein structure have been evaluated from 'dipolar-assisted rotational resonance' experiments recorded at various mixing times. Additional constraints on the backbone torsion angles have been derived from chemical shift analysis. Using both distance and dihedral angle constraints, the structure of microcrystalline ubiquitin has been refined to a root-mean-square deviation of about 1 A. The structure determination strategies for solid samples described herein are likely to be generally applicable to many proteins that cannot be studied by X-ray crystallography or solution NMR spectroscopy. PMID:15954766
September, 2004 (Adapted from Michael Sattler's Lectures at EMBL Heidelberg) Introduction to biomolecular NMR spectroscopy
Ritort, Felix
which can provide high-resolution structures of biological molecules such as proteins and nucleic acids ...................................................................................... 3 Methodological developments for structure determination by NMR ...........4 NMR in structural determination by solution NMR.....................................................14 NMR sample preparation
Dynamic processes and chemical composition of Lepidium sativum seeds determined by means of field-cycling NMR relaxometry and NMR spectroscopy.
Rachocki, A; Latanowicz, L; Tritt-Goc, J
Proton nuclear magnetic resonance (NMR) techniques, such as field-cycling relaxometry, wide-line NMR spectroscopy, and magic angle spinning NMR spectroscopy, were applied to study the seeds of cress, Lepidium sativum. Field-cycling NMR relaxometry was used for the first time to investigate the properties of the whole molecular system of dry cress seeds. This method not only allowed the dynamics to be studied, but was also successful in the differentiation among the solid (i.e., carbohydrates, proteins, or fats forming a solid form of lipids) and liquid-like (oil compounds) components of the seeds. The (1)H NMR relaxation dispersion of oils was interpreted as a superposition of intramolecular and intermolecular contributions. The intramolecular part was described in terms of a Lorentzian spectral density function, whereas a log-Gaussian distribution of correlation times was applied for the intermolecular dipole-dipole contribution. The models applied led to very good agreement with the experimental data and demonstrate that the contribution of the intermolecular relaxation to the overall relaxation should not be disregarded, especially at low frequencies. A power-law frequency dependence of the proton relaxation dispersion was used for the interpretation of the solid components. From the analysis of the (1)H wide-line NMR spectra of the liquid-like component of hydrated cress seeds, we can conclude that the contribution of oil protons should always be taken into account when evaluating the spin-lattice relaxation times values or measuring the moisture and oil content. The application of (1)H magic angle spinning NMR significantly improves resolution in the liquid-like spectrum of seeds and allows the determination of the chemical composition of cress seeds. PMID:23001307
Heteronuclear dipolar couplings, total spin coherence, and bilinear rotations in NMR spectroscopy
Garbow, J.R.
In Chapter 1 a variety of different introductory topics are presented. The potential complexity of the nuclear magnetic resonsnace (NMR) spectra of molecules dissolved in liquid crystal solvents serves to motivate the development of multiple quantum (MQ) spectroscopy. The basics of MQ NMR are reviewed in Chapter 2. An experimental search procedure for the optimization of MQ pulse sequences is introduced. Chapter 3 discusses the application of MQ NMR techniques to the measurement of dipolar couplings in heteronuclear spin systems. The advantages of MQ methods in such systems are developed and experimental results for partially oriented (1-/sup 13/C) benzene are presented. Several pulse sequences are introduced which employ a two-step excitation of heteronuclear MQ coherence. A new multiple pulse method, involving the simultaneous irradiation of both rare and abundant spin species, is described. The problem of the broadening of MQ transitions due to magnetic field inhomogeneity is considered in Chapter 4. The method of total spin coherence transfer echo spectroscopy (TSCTES) is presented, with experimets on partially oriented acetaldehyde serving to demonstrate this new technique. TSCTES results in MQ spectra which are sensitive to all chemical shifts and spin-spin couplings and which are free of inhomogeneous broadening. In Chapter 5 the spectroscopy of spin systems of several protons and a /sup 13/C nucleus in the isotropic phase is discussed. The usefulness of the heteronuclear bilinear rotation as a calculational tool is illustrated. Compensated bilinear ..pi.. rotations, which are relatively insensitive to timing parameter missets, are presented. A new technique for homonuclear proton decoupling, Bilinear Rotation Decoupling, is described and its success in weakly coupled systems is demonstrated.
Frontispiece: Labeling Strategy and Signal Broadening Mechanism of Protein NMR Spectroscopy in Xenopus laevis Oocytes.
Ye, Yansheng; Liu, Xiaoli; Chen, Yanhua; Xu, Guohua; Wu, Qiong; Zhang, Zeting; Yao, Chendie; Liu, Maili; Li, Conggang
NMR Spectroscopy In their Communication on page?8686?ff., C. Li et?al., demonstrate that (19) F labeling is a good first choice for studying globular and disordered proteins in Xenopus oocytes, especially compared with conventional (15) N- or (13) C-methyl enrichment. By using (19) F labeling, they found that, unlike E. coli cells, the viscosity in oocytes is only about 1.2?times that of water and that inhomogeneous broadening contributes 60-70?% to the line width. The labeling strategies and resonance broadening mechanisms in Xenopus oocytes were explored with the goal of expanding the application of this cell type. PMID:26017161
Stereochemical investigations on the diketopiperazine derivatives of enalapril and lisinopril by NMR spectroscopy
NASA Astrophysics Data System (ADS)
Demeter, ┴dßm; Fodor, Tamßs; Fischer, Jßnos
Stereochemical analysis of epimeric diketopiperazine (DKP) derivatives of enalapril and lisinopril has been performed by NMR spectroscopy. The present study focuses on the configurational assignment and conformational characteristics of the epimeric DKPs obtained from cyclization and subsequent base-catalyzed hydrolysis. We report full 1H and 13C assignments as obtained by a concerted use of 1D and 2D methods. The configuration of the respective stereogenic centres and the main conformational features were derived from the measured scalar and NOE connections. One conspicuous conformational feature of the sidechain is its tendency to bend over the piperazinedione ring.
Ultrafast Z-Spectroscopy for 129Xe NMR-Based Sensors
Boutin, Cķline; Lķonce, Estelle; Brotin, Thierry; Jerschow, Alexej; Berthault, Patrick
When working with hyperpolarized species, it is often difficult to maintain a stable level of magnetization over consecutive experiments, which renders their detection at the trace level cumbersome, even when combined with chemical exchange saturation transfer (CEST). We report herein the use of ultra-fast Z-spectroscopy as a powerful means to detect low concentrations of 129Xe NMR-based sensors and to measure the in-out xenon exchange. Modifications of the original sequence enable a multiplexed detection of several sensors, as well as the extraction of the exchange buildup rate constant in a single-shot fashion. PMID:24563724
1H and 2H NMR: Diagonal suppressed total correlation spectroscopy in spin echo mode
NASA Astrophysics Data System (ADS)
George, Christy; Chandrakumar, N.
We report a novel diagonal suppressed two-dimensional total correlation experiment in solution state and demonstrate its performance in 1H and 2H NMR. In DIagonal Suppressed spin echo TOtal Correlation SpectroscopY (DISTOCSY), diagonal peaks which occur around F1 = 0 in spin echo mode are removed by conversion to unobservable multiple quantum or longitudinal terms in each scan of a two scan procedure, on application of an appropriately phased 90░ pulse at the time of the echo maximum. The limitation of this approach to short FID acquisition times is discussed, and an alternative two-scan version of DISTOCSY for high resolution situations is presented.
1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems
NASA Astrophysics Data System (ADS)
Berns, Anne E.; Conte, Pellegrino
Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (?), such as protons, to the less abundant 13C nuclei with low ? values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; K÷gel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90░ x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched. The Hartmann-Hahn condition can be expressed as ?HB1H = ?CB1C, where ?H and ?C are the gyromagnetic ratios of protons and carbons, whereas B1H and B1C are the 1H and 13C radio-frequency (r.f.) fields applied to the nuclei. The Hartmann-Hahn condition is affected by the H-C dipolar interaction strength (Stejskal & Memory, 1994). All the factors affecting dipolar interactions may mismatch the Hartmann-Hahn condition and prevent a quantitative representation of the NOM chemical composition (Conte et al., 2004). It has been reported that under low speed MAS conditions, broad matching profiles are centered around the Hartmann-Hahn condition....... With increasing spinning speed the Hartmann-Hahn matching profiles break down in a series of narrow matching bands separated by the rotor frequency (Stejskal & Memory, 1994). In order to account for the instability of the Hartmann-Hahn condition at higher rotor spin rates (>10 kHz), variable amplitude cross-polarization techniques (RAMP-CP) have been developed (Metz et al., 1996). So far, to our knowledge, the prevailing way used to obtain quantitative 13C-CPMAS NMR results was to optimize the 1H and 13C spin lock r.f. fields on simple standard systems such as glycine and to use those r.f. field values to run experiments on unknown organic samples. The aim of the present study was to experimentally evidence that the stability of the Hartmann-Hahn condition was different for different samples with a known structure. Moreover, Hartmann-Hahn profiles of four different humic acids (HAs) were also provided in order to show that the 1H/13C r.f. spin lock field strength must also be tested on the HAs prior to a quantitative evaluation of their 13C-CPMAS NMR spectra. Baldock, J.A., Oades, J.M., Nelson, P.N., Skene, T.M., Golchin, A. & Clarke, P., 1997. Assessing the extent of decomposition of natural organic materials using solid-state C-13 NMR spectroscopy. Australian Journal of Soil Research, 35, 1061-1083. Conte, P., Piccolo, A., van Lagen, B., Buurman, P. & de Jager, P.A., 1997. Quantitative Aspects of So
Assignment of non-crystalline forms in cellulose I by CP\\/MAS 13C NMR spectroscopy
Kristina Wickholm; Per Tomas Larsson; Tommy Iversen
Non-crystalline forms of cellulose in birch pulp, cotton linters and Cladophora sp were studied by CP\\/MAS 13C NMR spectroscopy. New assignments were made for the NMR-signals in the lower shift part of the C-4 region (80¢86ppm). These signals were assigned to cellulose at accessible fibril surfaces, cellulose at inaccessible fibril surfaces and hemicellulose. Also, further evidence was found for para-crystalline
Orientation and Dynamics of an Antimicrobial Peptide in the Lipid Bilayer by Solid-State NMR Spectroscopy
Satoru Yamaguchi; Daniel Huster; Alan Waring; Robert I. Lehrer; William Kearney; Brian F. Tack; Mei Hong
The orientation and dynamics of an 18-residue antimicrobial peptide, ovispirin, has been investigated using solid-state NMR spectroscopy. Ovispirin is a cathelicidin-like model peptide (NH2-KNLRRIIRKIIHIIKKYG-COOH) with potent, broad-spectrum bactericidal activity. 15N NMR spectra of oriented ovispirin reconstituted into synthetic phospholipids show that the helical peptide is predominantly oriented in the plane of the lipid bilayer, except for a small portion of
Heterocyclic compounds used as corrosion inhibitors: correlation between 13C and 1H NMR spectroscopy and inhibition efficiency
E. m. m Sutter; F Ammeloot; M. J Pouet; C Fiaud; R Couffignal
Among the corrosion inhibitors of copper, four aromatic heterocyclic compounds, their corresponding sodium salts and Cu(I) complexes are studied using 13C NMR and 1H NMR spectroscopies in DMSO d6. With regard to the spectra of the neutral molecules, the spectra of the sodium salts are always shifted upfield. By contrast, the spectra of the copper complexes shift either downfield or
Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy
Ben Sellem, D.; Elbayed, K.; Neuville, A.; Moussallieh, F.-M.; Lang-Averous, G.; Piotto, M.; Bellocq, J.-P.; Namer, I. J.
Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient's survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using 1H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermore, a metabolic signature specific of serous (N-acetyl-aspartate) and mucinous (N-acetyl-lysine) carcinomas was found. The statistical models generated in this study are able to predict borderline tumors characterized by an intermediate metabolic pattern similar to the normal ovarian tissue. Finally and importantly, the statistical model of serous carcinomas provided good predictions of both patient's survival rates and the patient's response to chemotherapy. Conclusions. Despite the small number of samples used in this study, the results indicate that metabolomic analysis of intact tissues by HRMAS-NMR is a promising technique which might be applicable to the therapeutic management of patients. PMID:21577256
Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy.
Ben Sellem, D; Elbayed, K; Neuville, A; Moussallieh, F-M; Lang-Averous, G; Piotto, M; Bellocq, J-P; Namer, I J
Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient's survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using (1)H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermore, a metabolic signature specific of serous (N-acetyl-aspartate) and mucinous (N-acetyl-lysine) carcinomas was found. The statistical models generated in this study are able to predict borderline tumors characterized by an intermediate metabolic pattern similar to the normal ovarian tissue. Finally and importantly, the statistical model of serous carcinomas provided good predictions of both patient's survival rates and the patient's response to chemotherapy. Conclusions. Despite the small number of samples used in this study, the results indicate that metabolomic analysis of intact tissues by HRMAS-NMR is a promising technique which might be applicable to the therapeutic management of patients. PMID:21577256
Methylation patterns of aquatic humic substances determined by 13C NMR spectroscopy
Thorn, K.A.; Steelink, C.; Wershaw, R.L.
13C NMR spectroscopy is used to examine the hydroxyl group functionality of a series of humic and fulvic acids from different aquatic environments. Samples first are methylated with 13C-labeled diazomethane. The NMR spectra of the diazomethylated samples allow one to distinguish between methyl esters of carboxylic acids, methyl ethers of phenolic hydroxyls, and methyl ethers of phenolic hydroxyls adjacent to two substituents. Samples are then permethylated with 13C-labeled methyl iodide/NaH. 13C NMR spectra of permethylated samples show that a significant fraction of the hydroxyl groups is not methylated with diazomethane alone. In these spectra methyl ethers of carbohydrate and aliphatic hydroxyls overlap with methyl ethers of phenolic hydroxyls. Side reactions of the methyltion procedure including carbon methylation in the CH3I/NaH procedure, are also examined. Humic and fulvic acids from bog, swamp, groundwater, and lake waters showssome differences in their distribution of hydroxyl groups, mainly in the concentrations of phenolic hydroxyls, which may be attributed to their different biogeochemical origins. ?? 1987.
60ĀMHz (1)H NMR spectroscopy for the analysis of edible oils.
Parker, T; Limer, E; Watson, A D; Defernez, M; Williamson, D; Kemsley, E Kate
We report the first results from a new 60ĀMHz (1)H nuclear magnetic resonance (NMR) bench-top spectrometer, Pulsar, in a study simulating the adulteration of olive oil with hazelnut oil. There were qualitative differences between spectra from the two oil types. A single internal ratio of two isolated groups of peaks could detect hazelnut oil in olive oil at the level of ?13%w/w, whereas a whole-spectrum chemometric approach brought the limit of detection down to 11.2%w/w for a set of independent test samples. The Pulsar's performance was compared to that of Fourier transform infrared (FTIR) spectroscopy. The Pulsar delivered comparable sensitivity and improved specificity, making it a superior screening tool. We also mapped NMR onto FTIR spectra using a correlation-matrix approach. Interpretation of this heat-map combined with the established annotations of the NMR spectra suggested a hitherto undocumented feature in the IR spectrum at ?1130Ācm(-1), attributable to a double-bond vibration. PMID:24850979
Sensitivity and Resolution Enhancement in Solid-State NMR Spectroscopy of Bicelles
Dvinskikh, Sergey V.; Yamamoto, Kazutoshi; D³rr, Ulrich H. N.; Ramamoorthy, Ayyalusamy
Magnetically aligned bicelles are becoming attractive model membranes to investigate the structure, dynamics, geometry, and interaction of membrane-associated peptides and proteins using solution- and solid-state NMR experiments. Recent studies have shown that bicelles are more suitable than mechanically aligned bilayers for multidimensional solid-state NMR experiments. In this work, we describe experimental aspects of the natural abundance 13C and 14N NMR spectroscopy of DMPC/DHPC bicelles. In particular, approaches to enhance the sensitivity and resolution and to quantify radio frequency heating effects are presented. Sensitivity of 13C detection using single pulse excitation, conventional cross-polarization (CP), ramp-CP, and NOE techniques are compared. Our results suggest that the proton decoupling efficiency of the FLOPSY pulse sequence is better than that of continuous wave decoupling, TPPM, SPINAL and WALTZ sequences. A simple method of monitoring the water proton chemical shift is demonstrated for the measurement of sample temperature and calibration of the radio-frequency-induced heating in the sample. The possibility of using 14N experiments on bicelles is also discussed. PMID:17084096
Interaction of the replication terminator protein of Bacillus subtilis with DNA probed by NMR spectroscopy.
Hastings, Adam F; Otting, Gottfried; Folmer, Rutger H A; Duggin, Iain G; Wake, R Gerry; Wilce, Matthew C J; Wilce, Jacqueline A
Termination of DNA replication in Bacillus subtilis involves the polar arrest of replication forks by a specific complex formed between the dimeric 29 kDa replication terminator protein (RTP) and DNA terminator sites. We have used NMR spectroscopy to probe the changes in 1H-15N correlation spectra of a 15N-labelled RTP.C110S mutant upon the addition of a 21 base pair symmetrical DNA binding site. Assignment of the 1H-15N correlations was achieved using a suite of triple resonance NMR experiments with 15N,13C,70% 2H enriched protein recorded at 800 MHz and using TROSY pulse sequences. Perturbations to 1H-15N spectra revealed that the N-termini, alpha3-helices and several loops are affected by the binding interaction. An analysis of this data in light of the crystallographically determined apo- and DNA-bound forms of RTP.C110S revealed that the NMR spectral perturbations correlate more closely to protein structural changes upon complex formation rather than to interactions at the protein-DNA interface. PMID:16061201
Interaction of the replication terminator protein of Bacillus subtilis with DNA probed by NMR spectroscopy
Hastings, Adam F. [School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006 (Australia); Otting, Gottfried [Research School of Chemistry, Australian National University, Canberra, ACT (Australia); Folmer, Rutger H.A. [Structural Chemistry Laboratory, AstraZeneca R and D, S-431 83, Moelndal (Sweden); Duggin, Iain G. [School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006 (Australia); Wake, R. Gerry [School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006 (Australia); Wilce, Matthew C.J. [Biochemistry and Molecular Biology, Monash University, Melbourne, Vic. 3800 (Australia); Wilce, Jacqueline A. [Biochemistry and Molecular Biology, Monash University, Melbourne, Vic. 3800 (Australia)]. E-mail: email@example.com
Termination of DNA replication in Bacillus subtilis involves the polar arrest of replication forks by a specific complex formed between the dimeric 29 kDa replication terminator protein (RTP) and DNA terminator sites. We have used NMR spectroscopy to probe the changes in {sup 1}H-{sup 15}N correlation spectra of a {sup 15}N-labelled RTP.C110S mutant upon the addition of a 21 base pair symmetrical DNA binding site. Assignment of the {sup 1}H-{sup 15}N correlations was achieved using a suite of triple resonance NMR experiments with {sup 15}N,{sup 13}C,70% {sup 2}H enriched protein recorded at 800 MHz and using TROSY pulse sequences. Perturbations to {sup 1}H-{sup 15}N spectra revealed that the N-termini, {alpha}3-helices and several loops are affected by the binding interaction. An analysis of this data in light of the crystallographically determined apo- and DNA-bound forms of RTP.C110S revealed that the NMR spectral perturbations correlate more closely to protein structural changes upon complex formation rather than to interactions at the protein-DNA interface.
Biological effects and physical safety aspects of NMR imaging and in vivo spectroscopy
Tenforde, T.S.; Budinger, T.F.
An assessment is made of the biological effects and physical hazards of static and time-varying fields associated with the NMR devices that are being used for clinical imaging and in vivo spectroscopy. A summary is given of the current state of knowledge concerning the mechanisms of interaction and the bioeffects of these fields. Additional topics that are discussed include: (1) physical effects on pacemakers and metallic implants such as aneurysm clips, (2) human health studies related to the effects of exposure to nonionizing electromagnetic radiation, and (3) extant guidelines for limiting exposure of patients and medical personnel to the fields produced by NMR devices. On the basis of information available at the present time, it is concluded that the fields associated with the current generation of NMR devices do not pose a significant health risk in themselves. However, rigorous guidelines must be followed to avoid the physical interaction of these fields with metallic implants and medical electronic devices. 476 refs., 5 figs., 2 tabs.
Novel monosaccharide fermentation products in Caldicellulosiruptor saccharolyticus identified using NMR spectroscopy
Isern, Nancy G.; Xue, Junfeng; Rao, Jaya V.; Cort, John R.; Ahring, Birgitte K.
Profiles of metabolites produced by the thermophilic obligately anaerobic cellulose-degrading Gram-positive bacterium Caldicellulosiruptor saccharolyticus DSM 8903 strain following growth on different monosaccharides (D-glucose, D-mannose, L-arabinose, D-arabinose, D-xylose, L-fucose, and D-fucose) as carbon sources revealed several unexpected fermentation products, suggesting novel metabolic capacities and unexplored metabolic pathways in this organism. Both 1H and 13C nuclear magnetic resonance (NMR) spectroscopy were used to determine intracellular and extracellular metabolite profiles. Metabolite profiles were determined from 1-D 1H NMR spectra by curve fitting against spectral libraries provided in Chenomx software. To reduce uncertainties due to unassigned, overlapping, or poorly-resolved peaks, metabolite identifications were confirmed with 2-D homonuclear and heteronuclear NMR experiments. In addition to expected metabolites such as acetate, lactate, glycerol, and ethanol, several novel fermentation products were identified: ethylene glycol (from growth on D-arabinose, though not L-arabinose), acetoin and 2,3-butanediol (from D-glucose and L-arabinose), and hydroxyacetone (from D-mannose and L-arabinose). Production of ethylene glycol from D-arabinose was particularly notable, with around 10% of the substrate carbon converted into this uncommon fermentation product. The novel products have not previously been reported to be produced by C. saccharolyticus, nor would they be easily predicted from the current genome annotation, and show new potentials for using this strain for production of bioproducts.
The Development of 460 GHz gyrotrons for 700 MHz DNP-NMR spectroscopy
NASA Astrophysics Data System (ADS)
Idehara, T.; Tatematsu, Y.; Yamaguchi, Y.; Khutoryan, E. M.; Kuleshov, A. N.; Ueda, K.; Matsuki, Y.; Fujiwara, T.
Two demountable gyrotrons with internal mode converters were developded as sub-THz radiation sources for 700 MHz DNP (Dynamic Nuclear Polarization) enhanced NMR spectroscopy. Experimental study on the DNP-NMR spectroscopy will be carried out in Osaka University, Institute for Protein Research, as a collaboration with FIR UF. Both gyrotrons operate near 460 GHz and the output CW power measured at the end of transmission system made by circular waveguides is typically 20 to 30 watts. One of them named Gyrotron FU CW GVI (we are using "Gyrotron FU CW GO-1" as an official name in Osaka University) is designed to have a special function of high speed frequency modulation ?f within 100 MHz band. This will expand excitable band width of ESR and increase the number of electron spins contributing to DNP. The other gyrotron, Gyrotron FU CW GVIA ("Gyrotron FU CW GO-II") has a function of frequency tunability ?f in the range of wider than 1.5 GHz, which is achieved in steady state by changing magnetic field intensity. This function should be used for adjusting the output frequency at the optimal value to achieve the highest enhancement factor of DNP.
Localized in Vivo Isotropic-Anisotropic Correlation 1H NMR Spectroscopy Using Ultraslow Magic Angle Spinning
Wind, Robert A.; Hu, Jian Zhi; Majors, Paul D.
Previous work has shown that it is possible to separate the susceptibility broadening in the 1H NMR metabolite spectrum obtained in a live mouse from the isotropic information, thus significantly increasing the spectral resolution. This was achieved using ultra-slow magic angle spinning of the animal combined with a modified phase-corrected magic angle turning (PHORMAT) pulse sequence. However, PHORMAT cannot be used for spatially selective spectroscopy. In this article a modified sequence called LOCMAT (localized magic angle turning) is introduced that makes this possible. Proton LOCMAT spectra are shown for the liver and heart of a live mouse, while spinning the animal at a speed of 4 Hz in a 2 Tesla field. It was found that even in this relatively low field LOCMAT provided isotropic line widths that are a factor 4-10 times smaller than the ones obtained in a stationary animal, and that the susceptibility broadening of the heart metabolites shows unusual features not observed for a dead animal. Finally, the limitations of LOCMAT and possible ways to improve the technique are discussed. It is concluded that in vivo LOCMAT can significantly enhance the utility of NMR spectroscopy for biomedical research.
Labeling Strategy and Signal Broadening Mechanism of Protein NMR Spectroscopy in Xenopus laevis Oocytes.
Ye, Yansheng; Liu, Xiaoli; Chen, Yanhua; Xu, Guohua; Wu, Qiong; Zhang, Zeting; Yao, Chendie; Liu, Maili; Li, Conggang
We used Xenopus laevis oocytes, a paradigm for a variety of biological studies, as a eukaryotic model system for in-cell protein NMR spectroscopy. The small globular protein GB1 was one of the first studied in Xenopus oocytes, but there have been few reports since then of high-resolution spectra in oocytes. The scarcity of data is at least partly due to the lack of good labeling strategies and the paucity of information on resonance broadening mechanisms. Here, we systematically evaluate isotope enrichment and labeling methods in oocytes injected with five different proteins with molecular masses of 6 to 54?kDa. (19) F labeling is more promising than (15) N, (13) C, and (2) H enrichment. We also used (19) F?NMR spectroscopy to quantify the contribution of viscosity, weak interactions, and sample inhomogeneity to resonance broadening in cells. We found that the viscosity in oocytes is only about 1.2?times that of water, and that inhomogeneous broadening is a major factor in determining line width in these cells. PMID:25965532
Phosphorus Speciation of Sequential Extracts of Organic Amendments using NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Akinremi, O.
O.O. 1Akinremi Babasola Ajiboye and Donald N. Flaten 1Department of Soil Science, University of Manitoba, Winnipeg, R3T 2NT, Canada We carried out this study in order to determine the forms of phosphorus in various organic amendments using state-of-the art spectroscopic technique. Anaerobically digested biosolids (BIO), hog (HOG), dairy (DAIRY), beef (BEEF) and poultry (POULTRY) manures were subjected to sequential extraction. The extracts were analyzed by solution 31P nuclear magnetic resonance (NMR) spectroscopy. Most of the total P analysed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) in the sequential extracts of organic amendments were orthophosphate, except POULTRY, which was dominated by organic P. The labile P fraction in all the organic amendments, excluding POULTRY, was mainly orthophosphate P from readily soluble calcium and some aluminum phosphates. In the poultry litter, however, Ca phytate was the main P species controlling P solubility. Such knowledge of the differences in the chemical forms of phosphorus in organic amendments are essential for proper management of these amendments for agro-environmental purposes Key words: organic amendments, solution NMR, sequential fractionation, labile phosphorus
The Development of 460 GHz gyrotrons for 700 MHz DNP-NMR spectroscopy
NASA Astrophysics Data System (ADS)
Idehara, T.; Tatematsu, Y.; Yamaguchi, Y.; Khutoryan, E. M.; Kuleshov, A. N.; Ueda, K.; Matsuki, Y.; Fujiwara, T.
Two demountable gyrotrons with internal mode converters were developded as sub-THz radiation sources for 700 MHz DNP (Dynamic Nuclear Polarization) enhanced NMR spectroscopy. Experimental study on the DNP-NMR spectroscopy will be carried out in Osaka University, Institute for Protein Research, as a collaboration with FIR UF. Both gyrotrons operate near 460 GHz and the output CW power measured at the end of transmission system made by circular waveguides is typically 20 to 30 watts. One of them named Gyrotron FU CW GVI (we are using "Gyrotron FU CW GO-1" as an official name in Osaka University) is designed to have a special function of high speed frequency modulation ? f within 100 MHz band. This will expand excitable band width of ESR and increase the number of electron spins contributing to DNP. The other gyrotron, Gyrotron FU CW GVIA ("Gyrotron FU CW GO-II") has a function of frequency tunability ? f in the range of wider than 1.5 GHz, which is achieved in steady state by changing magnetic field intensity. This function should be used for adjusting the output frequency at the optimal value to achieve the highest enhancement factor of DNP.
High-Resolution Two-Dimensional J-Resolved NMR Spectroscopy for Biological Systems
Huang, Yuqing; Cai, Shuhui; Zhang, Zhiyong; Chen, Zhong
NMR spectroscopy is a principal tool in metabolomic studies and can, in theory, yield atom-level information critical for understanding biological systems. Nevertheless, NMR investigations on biological tissues generally have to contend with field inhomogeneities originating from variations in macroscopic magnetic susceptibility; these field inhomogeneities broaden spectral lines and thereby obscure metabolite signals. The congestion in one-dimensional NMR spectra of biological tissues often leads to ambiguities in metabolite identification and quantification. We propose an NMR approach based on intermolecular double-quantum coherences to recover high-resolution two-dimensional (2D) J-resolved spectra from inhomogeneous magnetic fields, such as those created by susceptibility variations in intact biological tissues. The proposed method makes it possible to acquire high-resolution 2D J-resolved spectra on intact biological samples without recourse to time-consuming shimming procedures or the use of specialized hardware, such as magic-angle-spinning probes. Separation of chemical shifts and J couplings along two distinct dimensions is achieved, which reduces spectral crowding and increases metabolite specificity. Moreover, the apparent J coupling constants observed are magnified by a factor of 3, facilitating the accurate measurement of small J couplings, which is useful in metabolic analyses. Dramatically improved spectral resolution is demonstrated in our applications of the technique on pig brain tissues. The resulting spectra contain a wealth of chemical shift and J-coupling information that is invaluable for metabolite analyses. A spatially localized experiment applied on an intact fish (Crossocheilus siamensis) reveals the promise of the proposed method in inĀvivo metabolite studies. Moreover, the proposed method makes few demands on spectrometer hardware and therefore constitutes a convenient and effective manner for metabonomics study of biological systems. PMID:24806938
High-resolution two-dimensional J-resolved NMR spectroscopy for biological systems.
Huang, Yuqing; Cai, Shuhui; Zhang, Zhiyong; Chen, Zhong
NMR spectroscopy is a principal tool in metabolomic studies and can, in theory, yield atom-level information critical for understanding biological systems. Nevertheless, NMR investigations on biological tissues generally have to contend with field inhomogeneities originating from variations in macroscopic magnetic susceptibility; these field inhomogeneities broaden spectral lines and thereby obscure metabolite signals. The congestion in one-dimensional NMR spectra of biological tissues often leads to ambiguities in metabolite identification and quantification. We propose an NMR approach based on intermolecular double-quantum coherences to recover high-resolution two-dimensional (2D) J-resolved spectra from inhomogeneous magnetic fields, such as those created by susceptibility variations in intact biological tissues. The proposed method makes it possible to acquire high-resolution 2D J-resolved spectra on intact biological samples without recourse to time-consuming shimming procedures or the use of specialized hardware, such as magic-angle-spinning probes. Separation of chemical shifts and J couplings along two distinct dimensions is achieved, which reduces spectral crowding and increases metabolite specificity. Moreover, the apparent J coupling constants observed are magnified by a factor of 3, facilitating the accurate measurement of small J couplings, which is useful in metabolic analyses. Dramatically improved spectral resolution is demonstrated in our applications of the technique on pig brain tissues. The resulting spectra contain a wealth of chemical shift and J-coupling information that is invaluable for metabolite analyses. A spatially localized experiment applied on an intact fish (Crossocheilus siamensis) reveals the promise of the proposed method in in vivo metabolite studies. Moreover, the proposed method makes few demands on spectrometer hardware and therefore constitutes a convenient and effective manner for metabonomics study of biological systems. PMID:24806938
Flexible Stoichiometry and Asymmetry of the PIDDosome Core Complex by Heteronuclear NMR Spectroscopy and Mass Spectrometry
Nematollahi, Lily A.; Garza-Garcia, Acely; Bechara, Chķrine; Esposito, Diego; Morgner, Nina; Robinson, Carol V.; Driscoll, Paul C.
Homotypic death domain (DD)¢DD interactions are important in the assembly of oligomeric signaling complexes such as the PIDDosome that acts as a platform for activation of caspase-2-dependent apoptotic signaling. The structure of the PIDDosome core complex exhibits an asymmetric three-layered arrangement containing five PIDD-DDs in one layer, five RAIDD-DDs in a second layer and an additional two RAIDD-DDs. We addressed complex formation between PIDD-DD and RAIDD-DD in solution using heteronuclear nuclear magnetic resonance (NMR) spectroscopy, nanoflow electrospray ionization mass spectrometry and size-exclusion chromatography with multi-angle light scattering. The DDs assemble into complexes displaying molecular masses in the range 130¢158ĀkDa and RAIDD-DD:PIDD-DD stoichiometries of 5:5, 6:5 and 7:5. These data suggest that the crystal structure is representative of only the heaviest species in solution and that two RAIDD-DDs are loosely attached to the 5:5 core. Two-dimensional 1H,15N-NMR experiments exhibited signal loss upon complexation consistent with the formation of high-molecular-weight species. 13C-Methyl-transverse relaxation optimized spectroscopy measurements of the PIDDosome core exhibit signs of differential line broadening, cross-peak splitting and chemical shift heterogeneity that reflect the presence of non-equivalent sites at interfaces within an asymmetric complex. Experiments using a mutant RAIDD-DD that forms a monodisperse 5:5 complex with PIDD-DD show that the spectroscopic signature derives from the quasi- but non-exact equivalent environments of each DD. Since this characteristic was previously demonstrated for the complex between the DDs of CD95 and FADD, the NMR data for this system are consistent with the formation of a structure homologous to the PIDDosome core. PMID:25528640
Analysis of technical lignins by two- and three-dimensional NMR spectroscopy.
Liitiõ, Tiina M; Maunu, Sirkka L; Hortling, Bo; Toikka, Merja; Kilpelõinen, Ilkka
Modern multidimensional NMR spectroscopic methods were applied to investigate the effects of kraft pulping and oxygen delignification on lignin side-chain structures. In addition to the two-dimensional HSQC measurements, the three-dimensional HSQC-TOCSY technique was utilized to elucidate the (1)H-(1)H and (1)H-(13)C correlations of individual spin systems and thus indicate a certain lignin side-chain structure. Unlike earlier, nonlabeled samples were used for 3D measurements. According to 2D and 3D NMR spectra, most of the structures identified in milled wood lignin (MWL) are still present in technical lignins after kraft pulping and oxygen delignification. Although the main reaction during kraft pulping is the cleavage of beta-O-4 linkages, these structures are still left in spent liquor lignin as well as in residual lignin. The amount of coniferyl alcohol and dihydroconiferyl alcohol end groups, as well as some unidentified saturated end groups, is higher in technical lignins than in MWL. Contrary to our earlier observations, no diphenylmethane structures were observed in any technical lignins. Vinyl aryl ether structures could not be detected in technical lignins either. PMID:12670147
NSDL National Science Digital Library
This site describes the theory and practice of IR and NMR spectroscopy for classroom and laboratory instruction. Although it is written for a course at the University of Colorado, Boulder, this site is appropriate for anyone doing analytical measurements with infrared or NMR.
Earle K. Plyler Prize for Molecular Spectroscopy Talk: Coherent Ultrafast Multidimensional Spectroscopy of Molecules; From NMR to X-rays
NASA Astrophysics Data System (ADS)
Mukamel, Shaul
Multidimensional spectroscopic techniques which originated with NMR in the 1970s have been extended over the past 15 years to the optical regime. NMR spectroscopists have developed methods for the design of pulse sequences that resolve otherwise congested spectra, enhance selected spectral features and reveal desired dynamical events. The major experimental and computational advances required for extending these ideas to study electronic and vibrational motions on the femtosecond timescale will be surveyed. The response of complex molecules and semiconductor nanostructures to sequences of optical pulses provides snapshots of their structure and dynamical processes. Two-dimensional correlation plots of the signals show characteristic cross-peak patterns which carry information about hydrogen bonding, secondary structure fluctuations of proteins and amyloid fibrils, and coherent and incoherent energy and charge transfer in photosynthetic complexes. Double quantum coherence signals that are induced by correlations among electrons or excitons allow the visualization of correlated wavefunctions. Future extensions to the attosecond regime using xray pulses will be discussed. Since core excitations are highly localized at selected atoms, such signals can monitor the motions of valence electron wavepackets in real space with atomic spatial resolution. Common principles underlying coherent spectroscopy techniques for spins, valence electrons, and core electronic excitations, spanning frequencies from radiowaves, infrared, ultraviolet all the way to hard X-rays will be discussed.
Synthesis and Resolution of the Atropisomeric 1,1'-Bi-2-Naphthol: An Experiment in Organic Synthesis and 2-D NMR Spectroscopy
ERIC Educational Resources Information Center
Mak, Kendrew K. W.
NMR spectroscopy is presented. It is seen that the experiment regarding the synthesis and resolution of 1,1'-Bi-2-naphtol presents a good experiment for teaching organic synthesis and NMR spectroscopy and provides a strategy for obtaining enantiopure compounds from achiral starting materials.
Sodium transport and phosphorus metabolism in sodium-loaded yeast: simultaneous observation with sodium-23 and phosphorus-31 NMR spectroscopy in vivo
Herbert Hoefeler; Dye Jensen; Martin M. Pike; Jean L. Delayre; Vincent P. Cirillo; Charles S. Springer; Eric T. Fossel; James A. Balschi
Simultaneous ┬▓┬│Na and ┬│┬╣P NMR spectra were obtained from a number of yeast suspensions. Prior to NMR spectroscopy, the yeast cells were Na-loaded: this replaced some of the intracellular K\\/sup +\\/ with Na\\/sup +\\/. These cells were also somewhat P-deficient in that they had no polyphosphate species visible in the ┬│┬╣P NMR spectrum. In the NMR experiments, the Na-loaded cells
Characterization of reactive intermediates by multinuclear diffusion-ordered NMR spectroscopy (DOSY).
Li, Deyu; Keresztes, Ivan; Hopson, Russell; Williard, Paul G
Nuclear magnetic resonance (NMR) is the most powerful and widely utilized technique for determining molecular structure. Although traditional NMR data analysis involves the correlation of chemical shift, coupling constant, and NOE interactions to specific structural features, a largely overlooked method introduced more than 40 years ago, pulsed gradient spin-echo (PGSE), measures diffusion coefficients of molecules in solution, thus providing their relative particle sizes. In the early 1990s, the PGSE sequence was incorporated into a two-dimensional experiment, dubbed diffusion-ordered NMR spectroscopy (DOSY), in which one dimension represents chemical shift data while the second dimension resolves species by their diffusion properties. This combination provides a powerful tool for identifying individual species in a multicomponent solution, earning the nickname "chromatography by NMR". In this Account, we describe our efforts to utilize DOSY techniques to characterize organometallic reactive intermediates in solution in order to correlate structural data to solid-state crystal structures determined by X-ray diffraction and to discover the role of aggregate formation and solvation states in reaction mechanisms. In 2000, we reported our initial efforts to employ DOSY techniques in the characterization of reactive intermediates such as organolithium aggregates. Since then, we have explored DOSY experiments with various nuclei beyond (1)H, including (6)Li, (7)Li, (11)B, (13)C, and (29)Si. Additionally, we proposed a diffusion coefficient-formula weight relationship to determine formula weight, aggregation number, and solvation state of reactive intermediates. We also introduced an internal reference system to correlate the diffusion properties of unknown reactive intermediates with known inert molecular standards, such as aromatic compounds, terminal olefins, cycloolefins, and tetraalkylsilanes. Furthermore, we utilized DOSY to interpret the role of aggregation number and solvation state of organometallic intermediates in the reactivity, kinetics, and mechanism of organic reactions. By utilizing multinuclear DOSY methodologies at various temperatures, we also correlated solid-state X-ray structures with those in solution and discovered new reactive complexes, including a monomeric boron enolate, a product-inhibition aggregate, and a series of intermediates in the vinyl lithiation of allyl amines. As highlighted by our efforts, DOSY techniques provide practical and feasible NMR procedures and hold the promise of even more powerful insights when extended to three-dimensional experiments. PMID:19105594
Aliphatic chain length by isotropic mixing (ALCHIM): determining composition of complex lipid samples by ╣H NMR spectroscopy.
Sachleben, Joseph R; Yi, Ruiyang; Volden, Paul A; Conzen, Suzanne D
Quantifying the amounts and types of lipids present in mixtures is important in fields as diverse as medicine, food science, and biochemistry. Nuclear magnetic resonance (NMR) spectroscopy can quantify the total amounts of saturated and unsaturated fatty acids in mixtures, but identifying the length of saturated fatty acid or the position of unsaturation by NMR is a daunting challenge. We have developed an NMR technique, aliphatic chain length by isotropic mixing, to address this problem. Using a selective total correlation spectroscopy technique to excite and transfer magnetization from a resolved resonance, we demonstrate that the time dependence of this transfer to another resolved site depends linearly on the number of aliphatic carbons separating the two sites. This technique is applied to complex natural mixtures allowing the identification and quantification of the constituent fatty acids. The method has been applied to whole adipocytes demonstrating that it will be of great use in studies of whole tissues. PMID:24831341
Refractory organic carbon in C-depleted arable soils, as studied by 13C NMR spectroscopy and carbohydrate analysis
Rita Kiem; Heike Knicker; Martin K÷rschens; Ingrid K÷gel-Knabner
Soil organic matter (SOM) comprises refractory compounds, to which a turnover time of more than 1000 years has been attributed in SOM models. The goal of this study is to characterize the chemical structure of refractory compounds of organic carbon in arable soils by means of 13C NMR spectroscopy and analysis of carbohydrates. C-depleted soils that are expected to be
Morphology changes during radiation-thermal degradation of polyethylene and an EPDM copolymer by 13C NMR spectroscopy
Roger A. Assink; Mathew Celina; Kenneth T. Gillen; Roger L. Clough; Todd M. Alam
The ? radiation induced degradation of an EPDM copolymer was compared to that of a 13C enriched polyethylene at exposure temperatures of 22 and 80░C. Morphological changes were measured by MAS 13C NMR spectroscopy and DSC. By first examining the high quality and less complex spectra of 13C enriched polyethylene, a protocol for the interpretation and deconvolution of the more
NMR Spectroscopy and Free Volume Analysis of the Effects of Copolymer Composition on the Swelling Kinetics and
Peppas, Nicholas A.
-Fickian transport; free vol- ume; NMR spectroscopy; polymer dynamics; poly(ethylene glycol); multiacrylates in all cases, due to the highly crosslinked nature of these materials. For poly(ethylene gly- col) di(meth)acrylates content as well as the number of ethylene glycol groups. The impact of varying the AA content
Organic solute changes with acidification in Lake Skjervatjern as shown by 1H-NMR spectroscopy
Malcolm, R.L.; Hayes, T.
1H-NMR spectroscopy has been found to be a useful tool to establish possible real differences and trends between all natural organic solute fractions (fulvic acids, humic acids, and XAD-4 acids) after acid-rain additions to the Lake Skjervatjern watershed. The proton NMR technique used in this study determined the spectral distribution of nonexchangeable protons among four peaks (aliphatic protons; aliphatic protons on carbon ?? or attached to electronegative groups; protons on carbons attached to O or N heteroatoms; and aromatic protons). Differences of 10% or more in the respective peak areas were considered to represent a real difference. After one year of acidification, fulvic acids decreased 13% (relative) in Peak 3 protons on carbon attached to N and O heteratoms and exhibited a decrease in aromatic protons between 27% and 31%. Humic acids also exhibited an 11% relative decrease in aromatic protons as a result of acidification. After one year of acidification, real changes were shown in three of the four proton assignments in XAD-4 acids. Peak 1 aliphatic protons increased by 14% (relative), Peak 3 protons on carbons attached to O and N heteroatoms decreased by 13% (relative), and aromatic protons (Peak 4) decreased by 35% (relative). Upon acidification, there was a trend in all solutes for aromatic protons to decrease and aliphatic protons to increase. The natural variation in organic solutes as shown in the Control Side B of the lake from 1990 to 1991 is perhaps a small limitation to the same data interpretations of acid rain changes at the Lake Skjervatjern site, but the proton NMR technique shows great promise as an independent scientific tool to detect and support other chemical techniques in establishing organic solute changes with different treatments (i.e., additions of acid rain).
Characterization of alkyl carbon in forest soils by CPMAS 13C NMR spectroscopy and dipolar dephasing
Kogel-Knabner, I.; Hatcher, P.G.
Samples obtained from forest soils at different stages of decomposition were treated sequentially with chloroform/methanol (extraction of lipids), sulfuric acid (hydrolysis), and sodium chlorite (delignification) to enrich them in refractory alkyl carbon. As revealed by NMR spectroscopy, this treatment yielded residues with high contents of alkyl carbon. In the NMR spectra of residues obtained from litter samples, resonances for carbohydrates are also present, indicating that these carbohydrates are tightly bound to the alkyl carbon structures. During decomposition in the soils this resistant carbohydrate fraction is lost almost completely. In the litter samples the alkyl carbon shows a dipolar dephasing behavior indicative of two structural components, a rigid and a more mobile component. As depth and decomposition increase, only the rigid component is observed. This fact could be due to selective degradation of the mobile component or to changes in molecular mobility during decomposition, e.g., because of an increase in cross linking or contact with the mineral matter of the soil.
Structure of lysozyme dissolved in neat organic solvents as assessed by NMR and CD spectroscopies.
Knubovets, T; Osterhout, J J; Klibanov, A M
The structure of the model protein hen egg-white lysozyme dissolved in water and in five neat organic solvents (ethylene glycol, methanol, dimethylsulfoxide (DMSO), formamide, and dimethylformamide (DMF)) has been examined by means of 1H NMR and circular dichroism (CD) spectroscopies. The NMR spectra of lysozyme reveal the lack of a defined tertiary structure in all five organic solvents, although the examination of line widths suggests the possibility of some ordered structure in ethylene glycol and in methanol. The near-UV CD spectra of the protein suggest no tertiary structure in lysozyme dissolved in DMSO, formamide, and DMF, while a distinctive (albeit less pronounced than in water) tertiary structure is seen in ethylene glycol and a drastically changed one in methanol. A highly developed secondary structure was observed by far-UV CD in ethylene glycol and methanol; interestingly, the alpha-helix content of the protein in both was greater than in water, while the beta-structure content was lower. (Solvent absorbance in the far-UV region prevents conclusions about the secondary structure in DMSO, formamide and DMF.) PMID:10099601
In situ and ex situ low-field NMR spectroscopy and MRI endowed by SABRE hyperpolarization.
Barskiy, Danila A; Kovtunov, Kirill V; Koptyug, Igor V; He, Ping; Groome, Kirsten A; Best, Quinn A; Shi, Fan; Goodson, Boyd M; Shchepin, Roman V; Truong, Milton L; Coffey, Aaron M; Waddell, Kevin W; Chekmenev, Eduard Y
By using 5.75 and 47.5 mT nuclear magnetic resonance (NMR) spectroscopy, up to 10(5)-fold sensitivity enhancement through signal amplification by reversible exchange (SABRE) was enabled, and subsecond temporal resolution was used to monitor an exchange reaction that resulted in the buildup and decay of hyperpolarized species after parahydrogen bubbling. We demonstrated the high-resolution low-field proton magnetic resonance imaging (MRI) of pyridine in a 47.5 mT magnetic field endowed by SABRE. Molecular imaging (i.e. imaging of dilute hyperpolarized substances rather than the bulk medium) was conducted in two regimes: in situ real-time MRI of the reaction mixture (in which pyridine was hyperpolarized), and ex situ MRI (in which hyperpolarization decays) of the liquid hyperpolarized product. Low-field (milli-Tesla range, e.g. 5.75 and 47.5 mT used in this study) parahydrogen-enhanced NMR and MRI, which are free from the limitations of high-field magnetic resonance (including susceptibility-induced gradients of the static magnetic field at phase interfaces), potentially enables new imaging applications as well as differentiation of hyperpolarized chemical species on demand by exploiting spin manipulations with static and alternating magnetic fields. PMID:25367202
Authentication of beef versus horse meat using 60 MHz 1H NMR spectroscopy.
Jakes, W; Gerdova, A; Defernez, M; Watson, A D; McCallum, C; Limer, E; Colquhoun, I J; Williamson, D C; Kemsley, E K
This work reports a candidate screening protocol to distinguish beef from horse meat based upon comparison of triglyceride signatures obtained by 60 MHz (1)H NMR spectroscopy. Using a simple chloroform-based extraction, we obtained classic low-field triglyceride spectra from typically a 10 min acquisition time. Peak integration was sufficient to differentiate samples of fresh beef (76 extractions) and horse (62 extractions) using Na've Bayes classification. Principal component analysis gave a two-dimensional "authentic" beef region (p=0.001) against which further spectra could be compared. This model was challenged using a subset of 23 freeze-thawed training samples. The outcomes indicated that storing samples by freezing does not adversely affect the analysis. Of a further collection of extractions from previously unseen samples, 90/91 beef spectra were classified as authentic, and 16/16 horse spectra as non-authentic. We conclude that 60 MHz (1)H NMR represents a feasible high-throughput approach for screening raw meat. PMID:25577043
1H NMR spectroscopy study of water adsorbed on the surface of layered ilerite
NASA Astrophysics Data System (ADS)
Pires, Clķo T. G. V. M. T.; Airoldi, Claudio
The hydrated layered alkaline silicate ilerite synthesized by a hydrothermal methodology was characterized by various techniques that confirmed a good structural quality of the resulted material. In an attempting to investigate the characteristics of water boundary layers in this hydrated powder sorbent, 1H NMR spectroscopy method was performed to measure the temperature dependence of the observed proton signal intensities in water sorbed, from 200.15 to 298.15 K. Gibbs energy of water molecules at the sorbent water interface decreased due to the sorption interactions, causing the water dosed to the sorbent surface freezes at T < 273.15 K. Due to a disturbing action of the sorbent surface and confined space, water occurs in the quasi-liquid state. As a result, it is observed in the 1H NMR spectra narrow signal relatively, but increase in peak broadening with the decrease of temperature. The presence of two types of hydrogen bonding was observed with the presence of signals around 3.9 and 16 ppm. The water at the interface freezes when the Gibbs energies of the sorbed water ice are identical. The variation of energy of ice observed in this material was 4.37 kJ mol-1 at 200.15 K with a decrease to null value at 298.15 K.
Quadruple-resonance magic-angle spinning NMR spectroscopy of deuterated solid proteins.
Akbey, ▄mit; Nieuwkoop, Andrew J; Wegner, Sebastian; Voreck, Anja; Kunert, Britta; Bandara, Priyanga; Engelke, Frank; Nielsen, Niels Chr; Oschkinat, Hartmut
(1)H-detected magic-angle spinning NMR experiments facilitate structural biology of solid proteins, which requires using deuterated proteins. However, often amide protons cannot be back-exchanged sufficiently, because of a possible lack of solvent exposure. For such systems, using (2)H?excitation instead of (1)H?excitation can be beneficial because of the larger abundance and shorter longitudinal relaxation time, T1, of deuterium. A new structure determination approach, "quadruple-resonance NMR spectroscopy", is presented which relies on an efficient (2)H-excitation and (2)H-(13)C cross-polarization (CP) step, combined with (1)H?detection. We show that by using (2)H-excited experiments better sensitivity is possible on an SH3 sample recrystallized from 30?% H2O. For a membrane protein, the ABC transporter ArtMP in native lipid bilayers, different sets of signals can be observed from different initial polarization pathways, which can be evaluated further to extract structural properties. PMID:24474388
Low Temperature 1H MAS NMR Spectroscopy Studies of Proton Motion in Zeolite
Huo, H.; Peng, L; Grey, C
Low temperature {sup 1}H MAS NMR spectroscopy is used to study protonic motion in zeolite HZSM-5 in both samples that have been dried using procedures that are standard in the literature and samples that have been more carefully dehydrated. A significant enhancement of proton mobility is seen for the ''standard'' dehydrated HZSM-5 sample in comparison to that seen for the much drier sample. This is ascribed to a vehicle-hopping mechanism involving the residual water that is present in these zeolites. A gradual change of the framework structure is observed on cooling to approximately 213 K, as monitored via the change in {sup 1}H chemical shift values of the Broensted acid resonances and by X-ray diffraction. A more sudden change in structure is seen by differential scanning calorimetry and NMR at approximately 220?230 K, which is associated with changes in both the mobility and the modes of binding of the residual water to the Broensted acid sites and the zeolite framework.
The Interaction between tRNALys3 and the Primer Activation Signal Deciphered by NMR Spectroscopy
Brachet, Franck; Tisne, Carine
The initiation of reverse transcription of the human immunodeficiency virus type 1 (HIV-1) requires the opening of the three-dimensional structure of the primer tRNALys3 for its annealing to the viral RNA at the primer binding site (PBS). Despite the fact that the result of this rearrangement is thermodynamically more stable, there is a high-energy barrier that requires the chaperoning activity of the viral nucleocapsid protein. In addition to the nucleotide complementarity to the PBS, several regions of tRNALys3 have been described as interacting with the viral genomic RNA. Among these sequences, a sequence of the viral genome called PAS for ōprimer activation signalö was proposed to interact with the T-arm of tRNALys3, this interaction stimulating the initiation of reverse transcription. In this report, we investigate the formation of this additional interaction with NMR spectroscopy, using a simple system composed of the primer tRNALys3, the 18 nucleotides of the PBS, the PAS (8 nucleotides) encompassed or not in a hairpin structure, and the nucleocapsid protein. Our NMR study provides molecular evidence of the existence of this interaction and highlights the role of the nucleocapsid protein in promoting this additional RNA-RNA annealing. This study presents the first direct observation at a single base-pair resolution of the PAS/anti-PAS association, which has been proposed to be involved in the chronological regulation of the reverse transcription. PMID:23762248
Spatially selective heteronuclear multiple-quantum coherence (HMQC) spectroscopy for bio-molecular NMR studies
Sathyamoorthy, Bharathwaj; Parish, David M.; Montelione, Gaetano T.; Xiao, Rong; Szyperski, Thomas
Spatially selective heteronuclear multiple-quantum coherence (SS HMQC) NMR spectroscopy was devised for solution studies of proteins. Due to ætime-staggeredÆ acquisition of free induction decays (FIDs) in different slices, SS HMQC allows one to employ long delays for longitudinal nuclear spin relaxation at high repetition rates for the acquisition of the FIDs. To also achieve high intrinsic sensitivity, SS HMQC was implemented by combing a single spatially selective 1H excitation pulse with non-selective 1H 180░ pulses. High-quality spectra could be obtained within 66 seconds for a 7.6 kDa uniformly 13C,15N-labeled protein, and within 45 and 90 seconds for, respectively, two uniformly 2H,13C,15N-labeled but isoleucine, leucine and valine methyl group protonated proteins with molecular weights of 7.5 and 43 kDa. PMID:24789578
Pulse design for broadband correlation NMR spectroscopy by multi-rotating frames
Coote, Paul; Arthanari, Haribabu; Yu, Tsyr-Yan; Natarajan, Amarnath; Wagner, Gerhard; Khaneja, Navin
We present a method for designing radio-frequency (RF) pulses for broadband or multi-band isotropic mixing at low power, suitable for protein NMR spectroscopy. These mixing pulses are designed analytically, rather than by numerical optimization, by repeatedly constructing new rotating frames of reference. We show how pulse parameters can be chosen frame-by-frame to systematically reduce the effective chemical shift bandwidth, but maintain most of the effective J-coupling strength. The effective Hartmann-Hahn mixing condition is then satisfied in a multi-rotating frame of reference. This design method yields multi-band and broadband mixing pulses at low RF power. In particular, the ratio of RF power to mixing bandwidth for these pulses is lower than for existing mixing pulses, such as DIPSI and FLOPSY. Carbon-carbon TOCSY experiments at low RF power support our theoretical analysis. PMID:23420125
Posttranslational modifications of intact proteins detected by NMR spectroscopy: application to glycosylation.
Schubert, Mario; Walczak, Michal J; Aebi, Markus; Wider, Gerhard
Posttranslational modifications (PTMs) are an integral part of the majority of proteins. The characterization of structure and function of PTMs can be very challenging especially for glycans. Existing methods to analyze PTMs require complicated sample preparations and suffer from missing certain modifications, the inability to identify linkage types and thus chemical structure. We present a direct, robust, and simple NMR spectroscopy method for the detection and identification of PTMs in proteins. No isotope labeling is required, nor does the molecular weight of the studied protein limit the application. The method can directly detect modifications on intact proteins without sophisticated sample preparation. This approach is well suited for diagnostics of proteins derived from native organisms and for the quality control of biotechnologically produced therapeutic proteins. PMID:25924827
Single-Quantum Coherence Filter for Strongly Coupled Spin Systems for Localized 1H NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Trabesinger, Andreas H.; Mueller, D. Christoph; Boesiger, Peter
A pulse sequence for localized in vivo1H NMR spectroscopy is presented, which selectively filters single-quantum coherence built up by strongly coupled spin systems. Uncoupled and weakly coupled spin systems do not contribute to the signal output. Analytical calculations using a product operator description of the strongly coupled AB spin system as well as in vitro tests demonstrate that the proposed filter produces a signal output for a strongly coupled AB spin system, whereas the resonances of a weakly coupled AX spin system and of uncoupled spins are widely suppressed. As a potential application, the detection of the strongly coupled AA?BB? spin system of taurine at 1.5 T is discussed.
Study of cyclic quaternary ammonium bromides by B3LYP calculations, NMR and FTIR spectroscopies.
Brycki, Bogumi?; Szulc, Adrianna; Kowalczyk, Iwona
N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas phase. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants confirm the optimized geometry. PMID:20714318
Quantitative analysis of sesquiterpene lactones in extract of Arnica montana L. by 1H NMR spectroscopy.
Staneva, Jordanka; Denkova, Pavletta; Todorova, Milka; Evstatieva, Ljuba
(1)H NMR spectroscopy was used as a method for quantitative analysis of sesquiterpene lactones present in a crude lactone fraction isolated from Arnica montana. Eight main components - tigloyl-, methacryloyl-, isobutyryl- and 2-methylbutyryl-esters of helenalin (H) and 11?,13-dihydrohelenalin (DH) were identified in the studied sample. The method allows the determination of the total amount of sesquiterpene lactones and the quantity of both type helenalin and 11?,13-dihydrohelenalin esters separately. Furthermore, 6-O-tigloylhelenalin (HT, 1), 6-O-methacryloylhelenalin (HM, 2), 6-O-tigloyl-11?,13-dihydrohelenalin (DHT, 5), and 6-O-methacryloyl-11?,13-dihydrohelenalin (DHM, 6) were quantified as individual components. PMID:20837387
Monitoring bound HA1(H1N1) and HA1(H5N1) on freely suspended graphene over plasmonic platforms with infrared spectroscopy
NASA Astrophysics Data System (ADS)
Banerjee, Amrita; Chakraborty, Sumit; Altan-Bonnet, Nihal; Grebel, Haim
Infrared (IR) spectroscopy provides fingerprinting of the energy and orientation of molecular bonds. The IR signals are generally weak and require amplification. Here we present a new plasmonic platform, made of freely suspended graphene, which was coating periodic metal structures. Only monolayer thick films were needed for a fast signal recording. We demonstrated unique IR absorption signals of bound proteins: these were the hemagglutinin area (HA1) of swine influenza (H1N1) and the avian influenza (H5N1) viruses bound to their respective tri-saccharides ligand receptors. The simplicity and sensitivity of such approach may find applications in fast monitoring of binding events.
The effects of cholesterol on magnetically aligned phospholipid bilayers: a solid-state NMR and EPR spectroscopy study
NASA Astrophysics Data System (ADS)
Lu, Jun-Xia; Caporini, Marc A.; Lorigan, Gary A.
This paper presents the first time that both solid-state NMR spectroscopy and EPR spectroscopy are used to study the effects of cholesterol on magnetically aligned phospholipid bilayers (bicelles). Solid-state deuterium NMR spectroscopy was carried out using both chain perdeuterated 1,2-dimyristoyl- sn-glycero-3-phosphatidylcholine (DMPC-d 54) and a partially deuterated ?-[2,2,3,4,4,6- 2H 6]cholesterol (cholesterol-d 6). Also, EPR spectroscopy was carried out utilizing a 3?-doxyl-5?-cholestane (cholestane) spin probe incorporated into magnetically aligned bilayers to provide a more complete picture about the ordering and dynamics of the phospholipid and cholesterol molecules in the bicelle membrane system. The results demonstrate that cholesterol was successfully incorporated into the phospholipid bilayers. The molecular order parameters extracted directly from the 2H NMR spectra of both DMPC-d 54 and cholesterol-d 6 were compared to that from the EPR study of cholestane. The order parameters indicate that the sterol was motionally restricted, and that the DMPC had high order and low motion for the hydrocarbon segments close to the head groups of the phospholipids and less order and more rapid motion toward the terminal methyl groups. Both methods clearly indicate an overall increase in the degree of ordering of the molecules in the presence of cholesterol and a decrease in the degree of ordering at higher temperatures. However, EPR spectroscopy and 2H NMR spectroscopy exhibit different degrees of sensitivity in detecting the phospholipid molecular motions in the membrane. Finally, cholesterol increases the minimum alignment temperature necessary to magnetically align the phospholipid bilayers.
Improvements in localized proton NMR spectroscopy of human brain. Water suppression, short echo times, and 1 ml resolution
NASA Astrophysics Data System (ADS)
Frahm, J.; Michaelis, T.; Merboldt, K. D.; Bruhn, H.; Gyngell, M. L.; Hõnicke, W.
Considerable technical improvements are reported for localized proton NMR spectroscopy using stimulated echoes. When compared to previous results, proton NMR spectra of the human brain are now obtainable (i) with in vivo water suppression factors of ?1000, (ii) with only minor T2 losses and negligible distortions due to J modulation at short echo times of 10-20 ms, and (iii) from volumes of interest as small as 1-8 ml within measuring times of 1-10 min. As a consequence, the detection of cerebral metabolites is greatly facilitated. This particularly applies to the assignment of those resonances (e.g., glutamate, taurine, inositols) that suffer from strong spin-spin coupling at the field strengths commonly in use for NMR in man. Studies of regional metabolite differences, tissue heterogeneity, and focal lesions in patients benefit from the increased spatial resolution and a concomitant reduction of partial volume effects. Localized proton NMR spectroscopy was performed on young healthy volunteers. Experiments were carried out on a 2.0 T whole-body MRI/MRS system using the standard headcoil for both imaging and spectroscopy.
NMR spectroscopy: a useful tool for characterisation of plant extracts, the case of supercritical CO 2 arnica extract
Anna Rita Bilia; Maria Camilla Bergonzi; Giovanni Mazzi; Franco Francesco Vincieri
The efficiency of two-dimensional homonuclear 1H¢1H correlated spectroscopy (COSY) and two-dimensional reverse heteronuclear shift correlation spectroscopy (i.e. heteronuclear multiple quantum correlation, HMQC) in characterising the content of the constituents of innovative extracts is demonstrated. These experiments were performed directly on a supercritical carbon dioxide (CO2) commercial extract of arnica and were able to fully characterise the active constituents, sesquiterpenes, and
Distinguishing Polymorphs of the Semiconducting Pigment Copper Phthalocyanine by Solid-state NMR and Raman Spectroscopy
Shaibat, Medhat A.; Casabianca, Leah B.; Siberio-Pķrez, Diana Y.; Matzger, Adam J; Ishii, Yoshitaka
Cu(II)(phthalocyanine) (CuPc) is broadly utilized as an archetypal molecular semiconductor and is the most widely used blue printing pigment. CuPc crystallizes in six different forms; the chemical and physical properties are substantially modulated by its molecular packing among these polymorphs. Despite the growing importance of this system, spectroscopic identification of different polymorphs for CuPc has posed difficulties. This study presents the first example of spectroscopic distinction of ?- and ?-forms of CuPc, the most widely used polymorphs, by solid-state NMR (SSNMR) and Raman spectroscopy. 13C high-resolution SSNMR spectra of ?- and ?-CuPc using very-fast magic angle spinning (VFMAS) at 20 kHz show that hyperfine shifts sensitively reflect polymorphs of CuPc. The experimental results were confirmed by ab initio chemical shift calculations. 13C and 1H SSNMR relaxation times of ?- and ?-CuPc under VFMAS also showed marked differences, presumably because of the difference in electronic spin correlation times in the two forms. Raman spectroscopy also provided another reliable method of differentiation between the two polymorphs. PMID:20225842
Exploring weak, transient protein-protein interactions in crowded in vivo environments by in-cell NMR spectroscopyå
Wang, Qinghua; Zhuravleva, Anastasia; Gierasch, Lila M.
Biology relies on functional interplay of proteins in the crowded and heterogeneous environment inside cells, and functional protein interactions are often weak and transient. Thus, methods are needed that preserve these interactions and provide information about them. In-cell NMR spectroscopy is an attractive method to study a proteinÆs behavior in cells because it may provide residue-level structural and dynamic information. Yet several factors limit the feasibility of protein NMR spectroscopy in cells, and among them slow rotational diffusion has emerged as the most important. In this paper, we seek to elucidate the causes of the dramatically slow protein tumbling in cells and in so doing to gain insight into how the intracellular viscosity and weak, transient interactions modulate protein mobility. To address these questions, we characterized the rotational diffusion of three model globular proteins in E. coli cells using 2D heteronuclear NMR spectroscopy. These proteins have a similar molecular size and globular fold, but very different surface properties, and indeed, they show very different rotational diffusion in the E. coli intracellular environment. Our data are consistent with an intracellular viscosity approximately eight times that of waterŚtoo low to be a limiting factor to observing small globular proteins by in-cell NMR spectroscopy. Thus, we conclude that transient interactions with cytoplasmic components significantly and differentially affect the mobility of proteins and therefore their NMR detectability. Moreover, we suggest that an intricate interplay of total protein charge and hydrophobic interactions plays a key role in regulating these weak intermolecular interactions in cells. PMID:21942871
Application of parahydrogen induced polarization techniques in NMR spectroscopy and imaging.
Duckett, Simon B; Mewis, Ryan E
Magnetic resonance provides a versatile platform that allows scientists to examine many different types of phenomena. However, the sensitivity of both NMR spectroscopy and MRI is low because the detected signal strength depends on the population difference that exists between the probed nuclear spin states in a magnetic field. This population difference increases with the strength of the interacting magnetic field and decreases with measurement temperature. In contrast, hyperpolarization methods that chemically introduce parahydrogen (a spin isomer of hydrogen with antiparallel spins that form a singlet) based on the traditional parahydrogen induced polarization (PHIP) approach tackle this sensitivity problem with dramatic results. In recent years, the potential of this method for MRI has been recognized, and its impact on medical diagnosis is starting to be realized. In this Account, we describe the use of parahydrogen to hyperpolarize a suitable substrate. This process normally involves the introduction of a molecule of parahydrogen into a target to create large population differences between nuclear spin states. The reaction of parahydrogen breaks the original magnetic symmetry and overcomes the selection rules that prevent both NMR observation and parahydrogen/orthohydrogen interconversion, yielding access to the normally invisible hyperpolarization associated with parahydrogen. Therefore the NMR or MRI measurement delivers a marked increase in the detected signal strength over the normal Boltzmann-population derived result. Consequently, measurements can be made which would otherwise be impossible. This approach was pioneered by Weitekamp, Bargon, and Eisenberg, in the late 1980s. Since 1993, we have used this technique in York to study reaction mechanisms and to characterize normally invisible inorganic species. We also describe signal amplification by reversible exchange (SABRE), an alternative route to sensitize molecules without directly incorporating a molecule of parahydrogen. This approach widens the applicability of PHIP methods and the range of materials that can be hyperpolarized. In this Account we describe our parahydrogen studies in York over the last 20 years and place them in a wider context. We describe the characterization of organometallic reaction intermediates including those involved in catalytic reactions, either with or without hydride ligands. The collection of spectroscopic and kinetic data with rapid inverse detection methods has proved to be particularly informative. We can see enhanced signals for the organic products of catalytic reactions that are linked directly to the catalytic intermediates that form them. This method can therefore prove unequivocally that a specific metal complex is involved in a catalytic cycle, thus pinpointing the true route to catalysis. Studies where a pure nuclear spin state is detected show that it is possible to detect all of the analyte molecules present in a sample using NMR. In addition, we describe methods that achieve the selective detection of these enhanced signals, when set against a strong NMR background such as that of water. PMID:22452702
Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids
NASA Astrophysics Data System (ADS)
Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert
We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (?, ?) in a series of selectively 13C-labeled 40-residue ?-amyloid (A?1-40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of A?1-40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16-21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ? and ? angles between the two carbonyl labels. Although the data are not sufficient to determine ? and ? uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of A?1-40 fibrils in 4 h or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples.
Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids
Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert
We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (?,?) in a series of selectively 13C-labeled 40-residue ?-amyloid (A?1¢40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of A?1¢40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16¢21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ? and ? angles between the two carbonyl labels. Although the data are not sufficient to determine ? and ? uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of A?1¢40 fibrils in 4 hr or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples. PMID:23562665
Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy
Debelouchina, Galia T.; Bayro, Marvin J.; Fitzpatrick, Anthony W.; Ladizhansky, Vladimir; Colvin, Michael T.; Caporini, Marc A.; Jaroniec, Christopher P.; Bajaj, Vikram S.; Rosay, Melanie; MacPhee, Cait E.; Vendruscolo, Michele; Maas, Werner E.; Dobson, Christopher M.; Griffin, Robert G.
Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that confer the extraordinary stability of the amyloid architecture. Despite these advances, however, obtaining atomic resolution information describing the higher levels of structural organization within the fibrils remains a significant challenge. Here, we detail MAS NMR experiments and sample labeling schemes designed specifically to probe such higher order amyloid structure and we have applied them to the fibrils formed by an eleven-residue segment of the amyloidogenic protein transthyretin (TTR(105-115)). These experiments have allowed us to define unambiguously not only the arrangement of the peptide ?-strands into ?-sheets but also the ?-sheet interfaces within each protofilament, and in addition to identify the nature of the protofilament-to-protofilament contacts that lead to the formation of the complete fibril. Our efforts have resulted in 111 quantitative distance and torsion angle restraints (10 per residue) that describe the various levels of structure organization. The experiments benefited extensively from the use of dynamic nuclear polarization (DNP), which in some cases allowed us to shorten the data acquisition time from days to hours and to improve significantly the signal-to-noise ratios of the spectra. The ?-sheet interface and protofilament interactions identified here revealed local variations in the structure that result in multiple peaks for the exposed N- and C-termini of the peptide and in inhomogeneous line-broadening for the side-chains buried within the interior of the fibrils. PMID:24304221
Rossaro, Lorenzo; Murase, Noriko; Caldwell, Cary; Farghali, Hassan; Casavilla, Adrian; Starzl, Thomas E.; Ho, Chien; Van Thiel, David H.
SUMMARY The ATP content and intracellular pH (pHi)3 of isolated rat liver before, during, and after cold preservation in either UW-lactobionate (UW, n=10) or Euro-Collins (EC, n=8) solutions were monitored using phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy. The 31P-NMR spectra were obtained on a 4.7-Tesla system operating at 81 MHz. Fructose metabolism, liver enzyme release, O2 consumption, and rat survival after liver transplantation were also evaluated. During simple cold storage (SCS), the ATP level declined to undetectable levels with both preservation solutions while the pHi declined to approximately 7.0. In contrast, during continuous hypothermic perfusion (CHP), hepatic ATP levels remained measurable during the 24-hour EC preservation and actually increased significantly (p>0.01) during UW preservation. After reperfusion at 37░C with Krebs-lactate, the SCS livers treated with EC differed significantly from the UW livers in terms of their ATP and pHi as well as their response to a fructose challenge. In contrast, livers undergoing CHP demonstrated similar behaviors with both solutions. These results demonstrate an increase in the hepatic ATP content during CHP which occurs with UW but is not seen with EC. On the other hand, only livers that were simply stored with UW achieved significant survival after transplant, while CHP livers were affected by vascular damage as demonstrated by fatal thrombosis after transplant. These data suggest that ATP content is not the only determinant of good liver function although a system of hypothermic perfusion might further improve liver preservation efficacy should injury to vascular endothelium be avoided. PMID:1402332
Structural models of activated ?-alumina surfaces revisited: Thermodynamics, NMR and IR spectroscopies from ab initio calculations
NASA Astrophysics Data System (ADS)
Ferreira, Ary R.; K³ń³kbenli, Emine; de Gironcoli, Stefano; Souza, Wladmir F.; Chiaro, Sandra Shirley X.; Konstantinova, Elena; LeitŃo, Alexandre A.
The activation of highly catalytic ?-alumina surfaces by thermal treatment and the description of the related chemical processes at atomic scale is a topical issue. According to a recent study [J. Am. Chem. Soc. 134 (2012) 14430], the enhanced reactivity of ?-alumina has been associated to tri-coordinated aluminum sites which supposedly are exposed exclusively on the (1 1 0) surfaces of this oxide. In this work, we explore this possibility by modeling the (1 0 0) and (1 1 0) terminations using Krokidis et al. [J. Phys. Chem. B 105 (2001) 5121] bulk structure and performing an extensive search of the most stable hydrated surface models at conditions consistent with experiment. Among the 156 structures analyzed, we identify several ōmetastableö models for the (1 1 0) surface with a considerable probability of containing the AlIII centers at OH coverages of 9.0 and 6.0 OH/nm2. We then test the reactivity of these sites through their Lewis acidity by simulating the CO adsorbtion on the surface and our results confirm the high reactivity of AlIII centers. Based on the Gibbs free energy of the explored structures, we carry on a thermodynamical analysis at varying hydroxylation degrees and pretreatment temperatures and simulate the experimental volcano-type behavior reported in [J. Am. Chem. Soc. 134 (2012) 14430] and predict the optimum pretreatment temperature as 700 ░C, in very good agreement with experimental findings. We further use infrared and solid state MAS NMR spectroscopies and reproduce the 1H MAS NMR spectra under high vacuum conditions (10-5 Torr). The strong resemblance of spectra to the experimental ones in the literature [J. Phys. Chem. C 116 (2012) 834] validate further the structural models we have generated in this study.
Molten-globule conformation of Arc repressor monomers determined by high-pressure 1H NMR spectroscopy.
Peng, X; Jonas, J; Silva, J L
The conformation of the pressure-dissociated monomer of Arc repressor was characterized by 1H NMR spectroscopy. The NMR spectra of the monomer under pressure (up to 5.0 kbar; 1 bar = 100 kPa) are typical of a molten globule and they are considerably different from those of the native dimer and thermally denatured monomer. The two-dimensional nuclear Overhauser effect spectra suggest that the pressure-induced molten globule retains some secondary structure. The presence of nuclear Overhauser effects in the beta-sheet region in the dissociated state suggests that the intermonomer beta-sheet (residues 8-14) in the native dimer is replaced by an intramonomer beta-sheet. Changes in one-dimensional and two-dimensional NMR spectra prior to pressure dissociation were found and suggest the existence of a "predissociated" state. Images Fig. 4 PMID:8446590
Technology Transfer Automated Retrieval System (TEKTRAN)
Spin counting on solid-state **13C cross-polarization (CP) nuclear magnetic resonance (NMR) spectra of two humic fractions isolated from tropical lowland soils showed that only 32-81% of potential **13C NMR signal was detected. The observability of **13C NMR signal (Cobs) was higher in the mobile h...
Sub-second 2D NMR Spectroscopy at Sub-millimolar Concentrations Boaz Shapira, Erel Morris, Karol A. Muszkat, and Lucio Frydman*,
Frydman, Lucio
Sub-second 2D NMR Spectroscopy at Sub-millimolar Concentrations Boaz Shapira, Erel Morris, Karol A of several consistent scans. Ultrafast 2D acquisition schemes, on the other hand, suffer from sensitivity that both kinds of complications could be simulta- neously lifted if pre-polarization and ultrafast 2D NMR
Silicon carbide polytype characterisation in coated fuel particles by Raman spectroscopy and 29Si magic angle spinning NMR
NASA Astrophysics Data System (ADS)
L¾pez-Honorato, E.; Brigden, C.; Shatwell, R. A.; Zhang, H.; Farnan, I.; Xiao, P.; Guillermier, P.; Somers, J.
The silicon carbide layer of a batch of as-produced TRISO (tristructural isotropic) coated fuel particles with zirconia kernels was characterised by Raman spectroscopy and magic angle spinning nuclear magnetic resonance (MAS-NMR). The techniques were evaluated as a probe for the evolution of SiC local structure as a function of chemical vapour deposition processing. Nuclear magnetic resonance resolved 29Si resonances for multiple hexagonal or cubic silicon local environments, consistent with a mixture of 6H, 15R and 4H polytypes, within a majority (36%) 3C-SiC target structure. Polarised Raman spectroscopy by contrast, showed some evidence of hexagonal and cubic local environments but no evidence for clearly defined hexagonal or orthorhombic polytypes. It was clear from the Raman that there was significant scattering from q > 0 regions of the Brillouin zone, consistent with a loss of translational symmetry associated with stacking faults. Simulation and TEM images suggested that the signals observed in Raman and NMR correspond closer to a random arrangement of SiC layers in which structures similar to the various polytypes occur over short distances. As NMR is a probe of local environment, the signals obtained were similar to those that would come from a mixture of crystallites, each of a well-defined polytype. The NMR data was analysed quantitatively by fitting the spectra of known polytypes and by using a simple model to represent the random arrangement of layers in a heavily faulted crystal.
Evidence is presented for the covalent binding of biologically reduced metabolites of 2,4,6-15N3-trinitrotoluene (TNT) to different soil fractions (humic acids, fulvic acids, and humin) using liquid 15N NMR spectroscopy. A silylation p...
The degradation of zinc dialkyldithiophosphate additives in fully formulated engine oil as studied by P-31 NMR spectroscopy
Pu Peng; Shan-Zhen Hong; Wan-Zhen Lu [SINOPEC, Beijing (China)
Two fully-formulated engine oils containing zinc dialkyldithiophosphate (ZDDP) were tested at different oil temperature regimes during long distance, high speed field tests (15000 km and 145 {plus_minus} 10 km/hr). P-31 NMR spectroscopy was used to characterize the ZDDPs and the degradation products formed during the field tests. It was found that basic ZDDP degradation products were thiophosphates and phosphates, and the thiophosphates could be further oxidized to form phosphates when the oil temperature was high. The dependence of the ZDDP degradation pathway with oil temperature is discussed. The amount of ZDDP in the used oil was related to the viscosity increase of that oil, which increased dramatically when the ZDDP was exhausted. In the fresh oil, ZDDP formed some sort of complex, but the complexed ZDDP was released during the field test as observed by P-31 NMR spectroscopy. 20 refs., 11 figs., 4 tabs.
Noninvasive measurements of glycogen in perfused mouse livers using chemical exchange saturation transfer NMR and comparison to (13)c NMR spectroscopy.
Miller, Corin O; Cao, Jin; Chekmenev, Eduard Y; Damon, Bruce M; Cherrington, Alan D; Gore, John C
Liver glycogen represents an important physiological form of energy storage. It plays a key role in the regulation of blood glucose concentrations, and dysregulations in hepatic glycogen metabolism are linked to many diseases including diabetes and insulin resistance. In this work, we develop, optimize, and validate a noninvasive protocol to measure glycogen levels in isolated perfused mouse livers using chemical exchange saturation transfer (CEST) NMR spectroscopy. Model glycogen solutions were used to determine optimal saturation pulse parameters which were then applied to intact perfused mouse livers of varying glycogen content. Glycogen measurements from serially acquired CEST Z-spectra of livers were compared with measurements from interleaved natural abundance (13)C NMR spectra. Experimental data revealed that CEST-based glycogen measurements were highly correlated with (13)C NMR glycogen spectra. Monte Carlo simulations were then used to investigate the inherent (i.e., signal-to-noise-based) errors in the quantification of glycogen with each technique. This revealed that CEST was intrinsically more precise than (13)C NMR, although in practice may be prone to other errors induced by variations in experimental conditions. We also observed that the CEST signal from glycogen in liver was significantly less than that observed from identical amounts in solution. Our results demonstrate that CEST provides an accurate, precise, and readily accessible method to noninvasively measure liver glycogen levels and their changes. Furthermore, this technique can be used to map glycogen distributions via conventional proton magnetic resonance imaging, a capability universally available on clinical and preclinical magnetic resonance imaging (MRI) scanners vs (13)C detection, which is limited to a small fraction of clinical-scale MRI scanners. PMID:25946616
Could smaller really be better? Current and future trends in high-resolution microcoil NMR spectroscopy.
Jones, Christopher J; Larive, Cynthia K
NMR is an invaluable analytical technique that provides structural and chemical information about a molecule without destroying the sample. However, NMR suffers from an inherent lack of sensitivity compared to other popular analytical techniques. This trends article focuses on strategies to increase the sensitivity of NMR using solenoidal microcoil, microstrip, and microslot probes. The role of these reduced-volume receiver coils for detection in hyphenated capillary electrophoresis (CE) and capillary isotachophoresis (cITP) NMR experiments is discussed. Future directions will likely build on work to develop probes containing multiple coils for high-throughput NMR and field-portable instruments. PMID:21879299
Aspects of the chemical structure of soil organic materials as revealed by solid-state13C NMR spectroscopy
J. A. Baldock; J. M. Oades; A. G. Waters; X. Peng; A. M. Vassallo; M. A. Wilson
Solid-state cross-polarisation\\/magic-angle-spinning3C nuclear magnetic resonance (CP\\/MAS13C NMR) spectroscopy was used to characterise semi-quantitatively the organic materials contained in particle size and density fractions isolated from five different mineral soils: two Mollisols, two Oxisols and an Andosol. The acquired spectra were analysed to determine the relative proportion of carboxyl, aromatic, O-alkyl and alkyl carbon contained in each fraction. Although similar types
Studies on the interactions between glycosylated ? 3-peptides and the lectin Vicia villosa by saturation transfer difference NMR spectroscopy
Marta Kaszowska; Anna S. Norgren; Per I. Arvidson; Corine Sandstr÷m
Saturation transfer difference (STD) NMR spectroscopy was used to study the interaction of the lectin Vicia villosa (VVLB4) with ?-d-GalNAc glycosylated ?3-peptides. The data were compared to those obtained with the monosaccharides d-Gal, d-GalNAc, and d-Glc as well as with those obtained with the Tn antigen ?-glycopeptide (d-GalNAc-?-O-Ser\\/Thr), molecule naturally recognized by V. villosa. Evidence that the lectin also recognizes
Method of Continuous Variation: Characterization of Alkali Metal Enolates Using 1H and 19F NMR Spectroscopies
The method of continuous variation in conjunction with 1H and 19F NMR spectroscopies was used to characterize lithium and sodium enolates solvated by N,N,N?,N?-tetramethylethyldiamine (TMEDA) and tetrahydrofuran (THF). A strategy developed using lithium enolates was then applied to the more challenging sodium enolates. A number of sodium enolates solvated by TMEDA or THF afford exclusively tetramers. Evidence suggests that TMEDA chelates sodium on cubic tetramers. PMID:24915602
Monitoring of cell volume and water exchange time in perfused cells by diffusion-weighted1H NMR spectroscopy
Josef Pfeuffer; Ulrich Fl÷gel; Dieter Leibfritz
Diffusion of intracellular water was measured in perfused cells embedded in basement membrane gel threads. F98 glioma cells, primary astrocytes, and epithelial KB cells were used and were exposed to osmotic stress, immunosuppressiva, the water channel blocker p-chloromercuriobenzenesulfonate (pCMBS), and apoptotic conditions. With diffusion-weighted 1H NMR spectroscopy changes in the intracellular signal could be monitored and quantified with single signal
Light induced E-Z isomerization in a multi-responsive organogel: elucidation from (1)H NMR spectroscopy.
Mondal, Sanjoy; Chakraborty, Priyadarshi; Bairi, Partha; Chatterjee, Dhruba P; Nandi, Arun K
A multiresponsive organogel of (E)-N'-(anthracene-10-ylmethylene)-3,4,5-tris(dodecyloxy)benzohydrazide () showed a decrease of fluorescence intensity, decrease in mechanical strength and a change in gel morphology on irradiation with a wavelength of 365 nm. This is attributed to the E-Z isomerization across the C[double bond, length as m-dash]N bond of as evidenced from (1)H NMR spectroscopy. PMID:26051426
Identification of tert-Butyl Cations in Zeolite H-ZSM-5: Evidence from NMR Spectroscopy and DFT Calculations.
Dai, Weili; Wang, Chuanming; Yi, Xianfeng; Zheng, Anmin; Li, Landong; Wu, Guangjun; Guan, Naijia; Xie, Zaiku; Dyballa, Michael; Hunger, Michael
Experimental evidence for the presence of tert-butyl cations, which are important intermediates in acid-catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with (1) H/(13) C magic-angle-spinning NMR spectroscopy, the tert-butyl cation was successfully identified on zeolite H-ZSM-5 upon conversion of isobutene by capturing this intermediate with ammonia. PMID:26096840
Application of 2D 1 H NMR spectroscopy to the study of the brain, spinal cord, and sciatic nerve
J. C. Beloeil; B. Gillet; O. Fedeli; G. Berenger; V. Lombardi; F. Marzullo; A. Scozzafava
Homonuclear1H 2D NMR spectroscopy (COSY experiments at 400 and 600 MHz) were used to study the rat brain in vivo and the rabbit spinal\\u000a cord and sciatic nerve in vitro. The following metabolites were identified: lactate, alanine, threonine, GABA, glutamine\\/glutamate,N-acetyl aspartate, aspartate, taurine, inositol derivatives, choline derivatives, and glucose. The sciatic nerve spectra showed\\u000a characteristic COSY graphs of saturated and
Quantitative Evaluation of the Lactate Signal Loss and Its Spatial Dependence in PRESS Localized 1H NMR Spectroscopy
Wulf-Ingo Jung; Michael Bunse; Otto Lutz
Localized 1H NMR spectroscopy using the 90░?t1?180░?t1+t2?180░?t2?Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t1 and t2. The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t1=t2) at an echo time of
Structural elucidation of the novel type VII group B Streptococcus capsular polysaccharide by high resolution NMR spectroscopy
Grigorij Kogan; Jean-Robert Brisson; Dennis L. Kasper; Christina von Hunolstein; Graziella Orefici; Harold J. Jennings
The type VII capsular polysaccharide isolated from the newly discovered group B Streptococcus (GBS) strain contains d-glucose, d-galactose, N-acetyl-d-glucosamine and N-acetylneuraminic acid in the molar ratio 2:2:1:1. High-resolution one- and two-dimensional (1D and 2D) 1H and 13C NMR spectroscopy of the native and desialylated polysaccharides showed the type VII GBS capsular polysaccharide to contain the following branched hexasaccharide repeating unit:?
Solid state NMR spectroscopy investigation of the molecular structure of epoxy based materials cured in different conditions
NASA Astrophysics Data System (ADS)
Alessi, S.; Spinella, A.; Caponetti, E.; Sabatino, Maria Antonietta; Spadaro, G.
In this work two epoxy resin model systems, whose monomers are typically used in structural composites, were thermally cured in different cure conditions in order to obtain different cross-linking densities. Their molecular structures were investigated through solid state NMR spectroscopy in order to correlate them to the cure process conditions used and the results were discussed in the light of the dynamical mechanical thermal analysis (DMTA) performed.
New insights on the structure of algaenan from Botryoccocus braunii race A and its hexane insoluble botryals based on multidimensional NMR spectroscopy and electrospray¢mass spectrometry techniques
Andre J Simpson; Xu Zang; Robert Kramer; Patrick G Hatcher
Through solution state NMR spectroscopy and quadrupole-time-of-flight mass spectrometry (Q-TOF MS) studies of the hexane insoluble botryal extract of the algae Botryococcus braunii race A, coupled with high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy of the algaenan from this alga, it has been possible to advance the structural understanding of this geochemically important biopolymer. It was found that the hexane insoluble botryals
Chromophore/DNA interactions: femto- to nanosecond spectroscopy, NMR structure, and electron transfer theory.
von Feilitzsch, Till; Tuma, Jennifer; Neubauer, Heike; Verdier, Laurent; Haselsberger, Reinhard; Feick, Reiner; Gurzadyan, Gagik; Voityuk, Alexander A; Griesinger, Christian; Michel-Beyerle, Maria E
The mechanism of photoinduced hole injection into DNA has been studied using an integrated approach that combines NMR structural analysis, time-resolved spectroscopy, and quantum-chemical calculations. A covalently linked acridinium derivative, the protonated 9-amino-6-chloro-2-methoxyacridine (X+), is replacing a thymine and separated from either guanine (G) or the easier to oxidize 7-deazaguanine (Z) by one adenine.thymine (A.T) base pair. The key features of this donor/acceptor system are the following: (i) In more than 95% of the duplexes, X+ is located in a central, coplanar position between the neighboring A.T base pairs with its long axis in parallel showing minimal twist and tilt angles (<15 degrees). The complementary adenine base is turned out into the extrahelical space. In a minority of less than 5%, X+ is found to be still attached to the duplex. X+ is most probably associated with one of the phosphates, since it is neither intercalated between more remote base pairs nor bound to sugars or grooves. This minority characterized by an excited state lifetime >10 ns gives rise to a small background signal in time-resolved measurements and contributes predominantly to steady-state fluorescence spectra. (ii) Although the intercalation mode of X+ is well defined, the NMR structure reveals that there are two conformations of X+ with respect to the arrangement of its methoxy substituent. In one conformation, the methoxy group is in the plane of the chromophore, while, in the other extraplanar conformation, the methoxy group forms an angle of 70 degrees with the acridinium ring. The fluorescence decay of 5'-ZAX and 5'-GAX tracts can be fitted to a biexponential function with similar amplitudes, reflecting the oxidation dynamics of G and Z, with the slower rate being determined by larger thermal activation energy. The attribution of biexponential electron transfer (ET) dynamics to the bimodal orientation of the methoxy group at the acridinium is supported by quantum-chemical calculations. These predict a larger free energy change for hole transfer in the nonplanar conformation as compared to the planar one, whereas the difference in the electronic couplings is negligible. (iii) Kinetic studies of the directionality of the 1(X+)* induced hole injection reveal similarly fast decay components in both directions of the duplex, that is, in 5'-ZAX and 5'-XAZ, with the amplitude of the fast component being significantly reduced in 5'-XAZ. The NMR structure shows that local structural deviations from B-DNA are much more pronounced in the 3'-5' direction than in the 5'-3' direction. According to quantum-chemical calculations, the directionality of charge injection is not a universal feature of the DNA duplex but depends critically on the rotation angle of the aromatic plane of the acridinium within the pi stack. The arrangement of X+ in 5'-ZAX and 5'-XAZ corresponds to a conformation with weak directionality of the electronic couplings. The increased disorder in the 3'-5'direction favors slow hole transfer components at the expense of the fast ones. (iv) A comparison of the hole transfer in 5'-GAX and 5'-ZAG shows that classical Marcus theory can explain the ratio of the charge shift rates of more than 2 orders of magnitude on the basis of a free energy difference between G and Z of 0.3 eV. Both NMR structures and quantum-chemical calculations justify the appreciable neglect of differences of electronic couplings as well as in the reorganization energy in 5'-GAX and 5'-ZAG. Despite the attractive concept for the behavior of floppy DNA oligonucleotides, in this acridinium/DNA system, there is no evidence for conformational gating, that is, for fluctuations in the electronic couplings that permit the ET to occur. PMID:18163608
Molecular Dynamics and NMR Spectroscopy Studies of E.Ācoli Lipopolysaccharide Structure and Dynamics
Wu, EmiliaĀL.; Engstr÷m, Olof; Jo, Sunhwan; Stuhlsatz, Danielle; Yeom, MinĀSun; Klauda, JefferyĀB.; Widmalm, G÷ran; Im, Wonpil
Lipopolysaccharide (LPS), a component of Gram-negative bacterial outer membranes, comprises three regions: lipid A, core oligosaccharide, and O-antigen polysaccharide. Using the CHARMM36 lipid and carbohydrate force fields, we have constructed a model of an Escherichia coli R1 (core) O6 (antigen) LPS molecule. Several all-atom bilayers are built and simulated with lipid A only (LIPA) and varying lengths of 0 (LPS0), 5 (LPS5), and 10 (LPS10) O6 antigen repeating units; a single unit of O6 antigen contains five sugar residues. From 1H,1H-NOESY experiments, cross-relaxation rates are obtained from an O-antigen polysaccharide sample. Although some experimental deviations are due to spin-diffusion, the remaining effective proton-proton distances show generally very good agreement between NMR experiments and molecular dynamics simulations. The simulation results show that increasing the LPS molecular length has an impact on LPS structure and dynamics and also on LPS bilayer properties. Terminal residues in a LPS bilayer are more flexible and extended along the membrane normal. As the core and O-antigen are added, per-lipid area increases and lipid bilayer order decreases. In addition, results from mixed LPS0/5 and LPS0/10 bilayer simulations show that the LPS O-antigen conformations at a higher concentration of LPS5 and LPS10 are more orthogonal to the membrane and less flexible. The O-antigen concentration of mixed LPS bilayers does not have a significant effect on per-lipid area and hydrophobic thickness. Analysis of ion and water penetration shows that water molecules can penetrate inside the inner core region, and hydration is critical to maintain the integrity of the bilayer structure. PMID:24047996
Metabolic footprinting study of white spruce somatic embryogenesis using NMR spectroscopy.
Dowlatabadi, Reza; Weljie, Aalim M; Thorpe, Trevor A; Yeung, Edward C; Vogel, Hans J
White spruce is an important commercial species for reforestation. The success in its propagation through somatic embryogenesis is well documented; however the physiological processes involved are poorly understood and remain unoptimized. The variable quality embryos generated in vitro from the same genotype suggest control at the protein and metabolite level. In order to probe metabolic changes, we have conducted a "metabolic footprinting" study, whereby culture media from growing cells was quantitatively analyzed to determine which metabolites were consumed and excreted. Such experiments are advantageous in that there is no need to quench cellular metabolism or extract intracellular metabolites through time-consuming protocols. In this paper we demonstrate the application of the footprinting assay to somatic embryo cells of white spruce (Picea glauca) using 1D (1)H NMR spectroscopy. We have surveyed embryogenesis metabolism in two types of media, maintenance (MN) and maturation (MT). MN medium does not result in shoot apical meristem (SAM) formation, while MT medium induces the necessary changes leading to fully developed somatic embryos. The two types of media were easily distinguished using metabolomics analysis, namely multivariate pattern recognition statistics (orthogonal partial least squares discriminatory analysis). From this analysis, we have identified numerous compounds involved with branched chain amino acid pathways such as valine and isoleucine. These results are explained on the basis of known metabolic pathways implicated in plant and animal developmental processes, and ultimately implicate altered CoA biosynthesis. PMID:19195904
1H NMR Spectroscopy and MVA Analysis of Diplodus sargus Eating the Exotic Pest Caulerpa cylindracea.
De Pascali, Sandra A; Del Coco, Laura; Felline, Serena; Mollo, Ernesto; Terlizzi, Antonio; Fanizzi, Francesco P
The green alga Caulerpa cylindracea is a non-autochthonous and invasive species that is severely affecting the native communities in the Mediterranean Sea. Recent researches show that the native edible fish Diplodus sargus actively feeds on this alga and cellular and physiological alterations have been related to the novel alimentary habits. The complex effects of such a trophic exposure to the invasive pest are still poorly understood. Here we report on the metabolic profiles of plasma from D. sargus individuals exposed to C. cylindracea along the southern Italian coast, using 1H NMR spectroscopy and multivariate analysis (Principal Component Analysis, PCA, Orthogonal Partial Least Square, PLS, and Orthogonal Partial Least Square Discriminant Analysis, OPLS-DA). Fish were sampled in two seasonal periods from three different locations, each characterized by a different degree of algal abundance. The levels of the algal bisindole alkaloid caulerpin, which is accumulated in the fish tissues, was used as an indicator of the trophic exposure to the seaweed and related to the plasma metabolic profiles. The profiles appeared clearly influenced by the sampling period beside the content of caulerpin, while the analyses also supported a moderate alteration of lipid and choline metabolism related to the Caulerpa-based diet. PMID:26058009
NMR Spectroscopy of Macrophages Loaded with Native, Oxidized or Enzymatically Degraded Lipoproteins
Ramm Sander, Paul; Peer, Markus; Grandl, Margot; Bogdahn, Ulrich; Schmitz, Gerd; Kalbitzer, Hans Robert
Oxidized and enzymatically modified low-density lipoproteins (oxLDL and eLDL) play a key role in early stages of atherogenesis. Their uptake by recruited macrophages leads to endolysosomal phospholipidosis or foam cell formation, respectively, each of which is preceded by highly differential lipid restructuring processes. We applied 1H-NMR spectroscopy (NMRS) to elucidate these structural rearrangements both in consequence of lipoprotein modifications and following phagocytosis. Being specifically sensitive to the mobile lipid subset, NMRS of oxLDL and eLDL revealed a partial and total immobilization of lipids, respectively. NMRS of intact macrophages showed a sixfold increase in mobile lipids in case of loading with eLDL but no significant changes for oxLDL or native LDL. This finding reflected the disparate lipid storage in lipid droplets and in multilamellar endolysosomal clusters when loaded with either eLDL or oxLDL, respectively. Moreover, a significant shift of the degree of saturation towards mainly polyunsaturated fatty acid chains was found for the mobile lipid pool in eLDL-loaded macrophages. Additional analyses of lipid extracts by NMRS and mass spectrometry (MS) reflected these changes in lipid content and in fatty acid composition only partially. In summary, in-cell NMRS represents a unique lipidomics tool to investigate structural changes within the mobile lipid pool following atherogenic triggers that can be not detected by the analysis of lipid extracts by MS or NMRS. PMID:23457556
NMR spectroscopy of macrophages loaded with native, oxidized or enzymatically degraded lipoproteins.
Ramm Sander, Paul; Peer, Markus; Grandl, Margot; Bogdahn, Ulrich; Schmitz, Gerd; Kalbitzer, Hans Robert
Oxidized and enzymatically modified low-density lipoproteins (oxLDL and eLDL) play a key role in early stages of atherogenesis. Their uptake by recruited macrophages leads to endolysosomal phospholipidosis or foam cell formation, respectively, each of which is preceded by highly differential lipid restructuring processes. We applied (1)H-NMR spectroscopy (NMRS) to elucidate these structural rearrangements both in consequence of lipoprotein modifications and following phagocytosis. Being specifically sensitive to the mobile lipid subset, NMRS of oxLDL and eLDL revealed a partial and total immobilization of lipids, respectively. NMRS of intact macrophages showed a sixfold increase in mobile lipids in case of loading with eLDL but no significant changes for oxLDL or native LDL. This finding reflected the disparate lipid storage in lipid droplets and in multilamellar endolysosomal clusters when loaded with either eLDL or oxLDL, respectively. Moreover, a significant shift of the degree of saturation towards mainly polyunsaturated fatty acid chains was found for the mobile lipid pool in eLDL-loaded macrophages. Additional analyses of lipid extracts by NMRS and mass spectrometry (MS) reflected these changes in lipid content and in fatty acid composition only partially. In summary, in-cell NMRS represents a unique lipidomics tool to investigate structural changes within the mobile lipid pool following atherogenic triggers that can be not detected by the analysis of lipid extracts by MS or NMRS. PMID:23457556
NMR spectroscopy reveals the presence and association of lipids and keratin in adhesive gecko setae.
Jain, Dharamdeep; Stark, Alyssa Y; Niewiarowski, Peter H; Miyoshi, Toshikazu; Dhinojwala, Ali
Lipid and protein aggregates are one of the fundamental materials of biological systems. Examples include cell membranes, insect cuticle, vertebrate epidermis, feathers, hair and adhesive structures known as 'setae' on gecko toes. Until recently gecko setae were assumed to be composed entirely of keratin, but analysis of footprints left behind by geckos walking on surfaces revealed that setae include various kinds of lipids. However, the arrangement and molecular-level behavior of lipids and keratin in the setae is still not known. In the present study we demonstrate, for the first time, the use of Nuclear Magnetic Resonance (NMR) spectroscopy techniques to confirm the presence of lipids and investigate their association with keratin in 'pristine' sheds, or natural molts of the adhesive toe pad and non-adhesive regions of the skin. Analysis was also carried on the sheds after they were 'delipidized' to remove surface lipids. Our results show a distribution of similar lipids in both the skin and toe shed but with different dynamics at a molecular level. The present study can help us understand the gecko system both biologically and for design of synthetic adhesives, but the findings may be relevant to the characteristics of lipid-protein interactions in other biological systems. PMID:25902194
Rapid preparation of RNA samples for NMR spectroscopy and X-ray crystallography
Cheong, Hae-Kap; Hwang, Eunha; Lee, Chulhyun; Choi, Byong-Seok; Cheong, Chaejoon
Knowledge of the three-dimensional structures of RNA and its complexes is important for understanding the molecular mechanism of RNA recognition by proteins or ligands. Enzymatic synthesis using T7 bacteriophage RNA polymerase is used to prepare samples for NMR spectroscopy and X-ray crystallography. However, this run-off transcription method results in heterogeneity at the RNA 3-terminus. For structural studies, RNA purification requires a single nucleotide resolution. Usually PAGE purification is used, but it is tedious, time-consuming and cost ineffective. To overcome these problems in high-throughput RNA synthesis, we devised a method of RNA preparation that uses trans-acting DNAzyme and sequence-specific affinity column chromatography. A tag sequence is added at the 3? end of RNA, and the tagged RNA is picked out using an affinity column that contains the complementary DNA sequence. The 3? end tag is then removed by sequence-specific cleavage using trans-acting DNAzyme, the arm lengths of which are optimized for turnover number. This purification method is simpler and faster than the conventional method. PMID:15199176
1H NMR Spectroscopy and MVA Analysis of Diplodus sargus Eating the Exotic Pest Caulerpa cylindracea
De Pascali, Sandra A.; Del Coco, Laura; Felline, Serena; Mollo, Ernesto; Terlizzi, Antonio; Fanizzi, Francesco P.
The green alga Caulerpa cylindracea is a non-autochthonous and invasive species that is severely affecting the native communities in the Mediterranean Sea. Recent researches show that the native edible fish Diplodus sargus actively feeds on this alga and cellular and physiological alterations have been related to the novel alimentary habits. The complex effects of such a trophic exposure to the invasive pest are still poorly understood. Here we report on the metabolic profiles of plasma from D. sargus individuals exposed to C. cylindracea along the southern Italian coast, using 1H NMR spectroscopy and multivariate analysis (Principal Component Analysis, PCA, Orthogonal Partial Least Square, PLS, and Orthogonal Partial Least Square Discriminant Analysis, OPLS-DA). Fish were sampled in two seasonal periods from three different locations, each characterized by a different degree of algal abundance. The levels of the algal bisindole alkaloid caulerpin, which is accumulated in the fish tissues, was used as an indicator of the trophic exposure to the seaweed and related to the plasma metabolic profiles. The profiles appeared clearly influenced by the sampling period beside the content of caulerpin, while the analyses also supported a moderate alteration of lipid and choline metabolism related to the Caulerpa-based diet. PMID:26058009
Detection of Anisotropy in Cartilage Using 2H Double-Quantum-Filtered NMR-Spectroscopy
NASA Astrophysics Data System (ADS)
Sharf, Y.; Eliav, U.; Shinar, H.; Navon, G.
Double-quantum-filtered (DQF) NMR spectroscopy of I = 1 spin systems is a diagnostic tool for the detection of anisotropy in macroscopically disordered systems. For deuterium, this method reveals the presence of a residual quadrupolar interaction for D 2O in bovine nasal cartilage. This tissue is not macroscopically ordered and the quadrupolar splitting is not resolved. Fitting the calculated spectral lineshapes to the experimental results was possible only when a distribution of the residual quadrupolar interaction, omega(q), was assumed. The series of DQF lineshapes obtained for different creation times in the DQF experiment could be fitted using a single set of three parameters: the average residual quadrupolar interaction overline? q/2? = 110 Hz, its standard deviation ?? q/2? = 73 Hz, and the transverse relaxation rate of 63 s -1. Separate deuterium DQF measurements for the constituents of the cartilage, collagen, and chondroitin sulfate indicated that the DQF spectra of cartilage are the result of anisotropic motion of D 2O due to binding to the fibrous collagen in the tissue.
Protein fold determined by paramagnetic magic-angle spinning solid-state NMR spectroscopy.
Sengupta, Ishita; Nadaud, Philippe S; Helmus, Jonathan J; Schwieters, Charles D; Jaroniec, Christopher P
Biomacromolecules that are challenging for the usual structural techniques can be studied with atomic resolution by solid-state NMR spectroscopy. However, the paucity of distance restraints >5Ā┼, traditionally derived from measurements of magnetic dipole-dipole couplings between protein nuclei, is a major bottleneck that hampers such structure elucidation efforts. Here, we describe a general approach that enables the rapid determination of global protein fold in the solid phase via measurements of nuclear paramagnetic relaxation enhancements (PREs) in several analogues of the protein of interest containing covalently attached paramagnetic tags, without the use of conventional internuclear distance restraints. The method is demonstrated using six cysteine-EDTA-Cu(2+) mutants of the 56-residue B1 immunoglobulin-binding domain of protein G, for which ~230 longitudinal backbone (15)N PREs corresponding to distances of ~10-20Ā┼ were obtained. The mean protein fold determined in this manner agrees with the X-ray structure with a backbone atom root-mean-square deviation of 1.8Ā┼. PMID:22522262
Metabolic responses during hemodialysis determined by quantitative (1)H NMR spectroscopy.
Fujiwara, Masako; Ando, Itiro; Takeuchi, Kazuhisa; Oguma, Shiro; Sato, Hiroshi; Sekino, Hiroshi; Sato, Keisuke; Imai, Yutaka
A large proportion of patients with end-stage renal disease have lifelong hemodialysis (HD) treatment. HD rapidly and indiscriminately removes necessary small metabolites together with uremic toxins from plasma into dialysate. To investigate metabolic responses to HD, we determined the levels of metabolites through time-course monitoring of (1)H NMR spectroscopy of dialysate during HD. The dialysate sample is stable for analysis because it contains only small metabolites without proteins. It was collected non-invasively from 9 HD patients with chronic glomerular nephropathy, at 6 time points during 4h of HD in 5 sessions. Creatinine, alanine, lactate, pyruvate and valine were simultaneously quantified on a one-dimensional single-pulse spectrum with a single standard compound. The concentration of creatinine exhibited monotonous decay with time, while that of valine decreased slowly and then maintained its levels throughout an HD. Lactate, alanine and pyruvate increased at 2-3h after the initiation of HD. They exhibited remarkable responses to HD with production from the body. The time-course of change in the 4 metabolites of lactate, pyruvate, alanine, and valine had reproducible behavior unique to each patient during the HD. This finding may be applied to distinguish metabolic status in HD patients. PMID:25886393
The microporous structure of coals and a microporous carbon studied using xenon-129 NMR spectroscopy
NASA Astrophysics Data System (ADS)
Anderson, Stasia A.
sp{129}Xe nuclear magnetic resonance spectroscopy of xenon gas adsorbed in coal is used to describe coal microporous structure. Emphasis is on establishing micropore diameter, whether pores are open, the type of connectivity, and changes associated with coal rank. Pressure dependent sp{129}Xe NMR spectra were acquired for a rank-varied set of coals. Micropore diameters calculated from the spectra range from 5.6 to 7.5 A and are related to coal rank. Signal linewidths decrease with increasing coal rank. The packing density of powdered coal affected the spectral appearance. Micropore diameters were also calculated for a microporous carbon before and after pore-size alteration. Selective low power presaturation of the adsorbed xenon signal for four coals produces a hole-burning effect in the spectra indicating that the signal is composed of a series of overlapped chemical shifts. Saturation transfer to the external gas signal, (which most likely originates from xenon in large pores) is observed as presaturation time is increased. Saturation transfer occurs significantly faster in two low-rank than in two higher-rank coals. The process of xenon adsorption was monitored by acquisition of sp{129}Xe NMR during adsorption. Equilibrium is achieved faster in smaller particle size anthracite than in larger, and for either, the time is slower than for the microporous carbon. The external xenon is observed only in the larger particle size and loses intensity as the internally-adsorbed xenon increases. No intermediate signal location is indicated prior to equilibrium. These experiments indicate coal porosity is open and that it constitutes a constricted network. The degree of constriction is higher in coals over ś89% carbon. Microporosity in low-rank coals is consistent with a dendritic pore structure. For higher rank coals over 89% carbon, the microporosity is more isolated and is open via constricted micropores but lacks a route through larger pores. Smaller particle size anthracite has less constriction in its porosity than larger particle size, and may also have less larger porosity or fracture.
Investigation of molecular structure in solids by two-dimensional NMR exchange spectroscopy with magic angle spinning
NASA Astrophysics Data System (ADS)
Tycko, Robert; Weliky, David P.; Berger, Alan E.
An approach to the investigation of molecular structures in disordered solids, using two-dimensional (2D) nuclear magnetic resonance (NMR) exchange spectroscopy with magic angle spinning (MAS), is described. This approach permits the determination of the relative orientation of two isotopically labeled chemical groups within a molecule in an unoriented sample, thus placing strong constraints on the molecular conformation. Structural information is contained in the amplitudes of crosspeaks in rotor-synchronized 2D MAS exchange spectra that connect spinning sideband lines of the two labeled sites. The theory for calculating the amplitudes of spinning sideband crosspeaks in 2D MAS exchange spectra, in the limit of complete magnetization exchange between the labeled sites, is presented in detail. A new technique that enhances the sensitivity of 2D MAS exchange spectra to molecular structure, called orientationally weighted 2D MAS exchange spectroscopy, is introduced. Symmetry principles that underlie the construction of pulse sequences for orientationally weighted 2D MAS exchange spectroscopy are explained. Experimental demonstrations of the utility of 2D MAS exchange spectroscopy in structural investigations of peptide and protein backbone conformations are carried out on a model 13C-labeled tripeptide, L-alanylglycylglycine. The dihedral angles ? and ? that characterize the peptide backbone conformation at Gly-2 are obtained accurately from the orientationally weighted and unweighted 2D 13C NMR exchange spectra.
Practical aspects of Lee Goldburg based CRAMPS techniques for high-resolution 1H NMR spectroscopy in solids: Implementation and applications
NASA Astrophysics Data System (ADS)
Coelho, Cristina; Rocha, JoŃo; Madhu, P. K.; Mafra, LuĒs
Elucidating the local environment of the hydrogen atoms is an important problem in materials science. Because 1H spectra in solid-state nuclear magnetic resonance (NMR) suffer from low resolution due to homogeneous broadening, even under magic-angle spinning (MAS), information of chemical interest may only be obtained using certain high-resolution 1H MAS techniques. 1H Lee-Goldburg (LG) CRAMPS (Combined Rotation And Multiple-Pulse Spectroscopy) methods are particularly well suited for studying inorganic-organic hybrid materials, rich in 1H nuclei. However, setting up CRAMPS experiments is time-consuming and not entirely trivial, facts that have discouraged their widespread use by materials scientists. To change this status quo, here we describe and discuss some important aspects of the experimental implementation of CRAMPS techniques based on LG decoupling schemes, such as FSLG (Frequency Switched), and windowed and windowless PMLG (Phase Modulated). In particular, we discuss the influence on the quality of the 1H NMR spectra of the different parameters at play, for example LG (Lee-Goldburg) pulses, radio-frequency ( rf) phase, frequency switching, and pulse imperfections, using glycine and adamantane as model compounds. The efficiency and robustness of the different LG-decoupling schemes is then illustrated on the following materials: organo-phosphorus ligand, N-(phosphonomethyl)iminodiacetic acid [H 4pmida] [I], and inorganic-organic hybrid materials (C 4H 12N 2)[Ge 2(pmida) 2OH 2]Ę4H 2O [II] and (C 2H 5NH 3)[Ti(H 1.5PO 4)(PO 4)] 2ĘH 2O [III].
In vivo1H NMR spectroscopy of the human brain at 9.4 T: Initial results
NASA Astrophysics Data System (ADS)
Deelchand, Dinesh Kumar; Moortele, Pierre-Franńois Van de; Adriany, Gregor; Iltis, Isabelle; Andersen, Peter; Strupp, John P.; Thomas Vaughan, J.; U?urbil, KŌmil; Henry, Pierre-Gilles
In vivo proton NMR spectroscopy allows non-invasive detection and quantification of a wide range of biochemical compounds in the brain. Higher field strength is generally considered advantageous for spectroscopy due to increased signal-to-noise and increased spectral dispersion. So far 1H NMR spectra have been reported in the human brain up to 7 T. In this study we show that excellent quality short echo time STEAM and LASER 1H NMR spectra can be measured in the human brain at 9.4 T. The information content of the human brain spectra appears very similar to that measured in the past decade in rodent brains at the same field strength, in spite of broader linewidth in human brain. Compared to lower fields, the T1 relaxation times of metabolites were slightly longer while T2 relaxation values of metabolites were shorter (<100 ms) at 9.4 T. The linewidth of the total creatine (tCr) resonance at 3.03 ppm increased linearly with magnetic field (1.35 Hz/T from 1.5 T to 9.4 T), with a minimum achievable tCr linewidth of around 12.5 Hz at 9.4 T. At very high field, B0 microsusceptibility effects are the main contributor to the minimum achievable linewidth.
Metabotyping of Long-Lived Mice using 1H NMR Spectroscopy
Significant advances in understanding aging have been achieved through studying model organisms with extended healthy lifespans. Employing 1H NMR spectroscopy, we characterized the plasma metabolic phenotype (metabotype) of three long-lived murine models: 30% dietary restricted (DR), insulin receptor substrate 1 null (Irs1¢/¢), and Ames dwarf (Prop1df/df). A panel of metabolic differences were generated for each model relative to their controls, and subsequently, the three long-lived models were compared to one another. Concentrations of mobile very low density lipoproteins, trimethylamine, and choline were significantly decreased in the plasma of all three models. Metabolites including glucose, choline, glycerophosphocholine, and various lipids were significantly reduced, while acetoacetate, d-3-hydroxybutyrate and trimethylamine-N-oxide levels were increased in DR compared to ad libitum fed controls. Plasma lipids and glycerophosphocholine were also decreased in Irs1¢/¢ mice compared to controls, as were methionine and citrate. In contrast, high density lipoproteins and glycerophosphocholine were increased in Ames dwarf mice, as were methionine and citrate. Pairwise comparisons indicated that differences existed between the metabotypes of the different long-lived mice models. Irs1¢/¢ mice, for example, had elevated glucose, acetate, acetone, and creatine but lower methionine relative to DR mice and Ames dwarfs. Our study identified several potential candidate biomarkers directionally altered across all three models that may be predictive of longevity but also identified differences in the metabolic signatures. This comparative approach suggests that the metabolic networks underlying lifespan extension may not be exactly the same for each model of longevity and is consistent with multifactorial control of the aging process. PMID:22225495
Enhanced resolution and quantitation from `ultrahigh' eld NMR spectroscopy of glasses
Puglisi, Joseph
for nuclear magnetic resonance (NMR) (e.g., 14.1 and 18.8 T) can enhance both resolution and sensitivity «elds. Examples include site distinction of multiple boron groupings in 11 B MAS NMR spectra of borate in the devel- opment of structural and dynamical models of glass structure [1▒3]. The chemical shift is a sen
Improved technique for investigation of cell metabolism by 31 P NMR spectroscopy
Lev Jacobson; Jack S. Cohen
SIp NMR studies on microorganisms have been carried out with the cells embedded in agarose gel. The novel use of the gel for the NMR studies has advantages over the usual liquid suspensions in terms of improved reproducibility of data and cell viability, with no net loss of spectral quality. Polyphosphate formation in Escherichia coli was monitored continuously for up
Metabolite Characterization in Peritoneal Dialysis Effluent Using High-resolution 1H and 1H-13C NMR Spectroscopy
Guleria, Anupam; Rawat, Atul; Khetrapal, C L; Prasad, Narayan; Kumar, Dinesh
Metabolite analysis of peritoneal dialysis (PD) effluent may provide information regarding onset and progression of complications associated with prolonged PD therapy. In this context, the NMR detectable small metabolites of PD effluent samples were characterized using high resolution 1H and 1H-13C NMR spectroscopy. The various spectra were recorded (at 800 MHz proton frequency) on PD effluent samples obtained after 4 hour (intraperitoneal) dwell time from patients with end stage renal failure (ESRF) and continuing normally on PD therapy. Inspite of devastating spectral feature of PD effluent due to the presence of intense resonances from glucose and lactate, we were able to identify about 53 small endogenous metabolites (including many complex coupled spin systems) and more than 90 % of the total CH cross peaks of 1H-13C HSQC spectrum were identified specific to various metabolites of PD effluent. We foresee that the characteristic fingerprints of various metabolites of control PD effluent samples will be us...
Real-Time Monitoring of New Delhi Metallo-?-Lactamase Activity in Living Bacterial Cells by 1H NMR Spectroscopy**
Ma, Junhe; McLeod, Sarah; MacCormack, Kathleen; Sriram, Shubha; Gao, Ning; Breeze, Alexander L; Hu, Jun
Disconnections between in vitro responses and those observed in whole cells confound many attempts to design drugs in areas of serious medical need. A method based on 1D 1H NMR spectroscopy is reported that affords the ability to monitor the hydrolytic decomposition of the carbapenem antibiotic meropenem inside Escherichia coli cells expressing New Delhi metallo-?-lactamase subclass 1 (NDM-1), an emerging antibiotic-resistance threat. Cell-based NMR studies demonstrated that two known NDM-1 inhibitors, L-captopril and ethylenediaminetetraacetic acid (EDTA), inhibit the hydrolysis of meropenem in vivo. NDM-1 activity in cells was also shown to be inhibited by spermine, a porin inhibitor, although in an in vitro assay, the influence of spermine on the activity of isolated NDM-1 protein is minimal. This new approach may have generic utility for monitoring reactions involving diffusible metabolites in other complex biological matrices and whole-cell settings, including mammalian cells. PMID:24458501
╣H NMR spectroscopy reveals the effect of genotype and growth conditions on composition of sea buckthorn (Hippophaļ rhamnoides L.) berries.
Kortesniemi, Maaria; Sinkkonen, Jari; Yang, Baoru; Kallio, Heikki
╣H NMR spectroscopy and multivariate data analysis were applied to the metabolic profiling and discrimination of wild sea buckthorn (Hippophaļ rhamnoides L.) berries from different locations in Finland (subspecies (ssp.) rhamnoides) and China (ssp. sinensis). Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) showed discrimination of the two subspecies and different growth sites. The discrimination of ssp. rhamnoides was mainly associated with typically higher temperature, radiation and humidity and lower precipitation in the south, yielding higher levels of O-ethyl ?-d-glucopyranoside and d-glucose, and lower levels of malic, quinic and ascorbic acids. Significant metabolic differences (p<0.05) in genetically identical berries were observed between latitudes 60░ and 67░ north in Finland. High altitudes (> 2,000 m) correlated with greater levels of malic and ascorbic acids in ssp. sinensis. The NMR metabolomics approach applied here is effective for identification of metabolites, geographical origin and subspecies of sea buckthorn berries. PMID:24206697
Structure and ionic interactions of organic-inorganic composite polymer electrolytes studied by solid-state NMR and Raman spectroscopy.
Joo, Chan Gyu; Bronstein, Lyudmila M; Karlinsey, Robert L; Zwanziger, Josef W
Solid-state NMR studies of composite polymer electrolytes are reported. The materials consist of polyethylene oxide and an organic inorganic composite, together with a lithium salt, and are candidates for electrolytes in solid-state lithium ion batteries. Silicon and aluminum MAS and multiple quantum MAS are used to characterize the network character of the organic-inorganic composite, and spin diffusion measurements are used to determine the nanostructure of the polymer/composite blending. Multiple quantum spin counting is used to measure the ion aggregation. The NMR results are supported by Raman spectra, calorimetry, and impedance spectroscopy. From these experiments it is concluded that the composite suppresses polymer crystallization without suppressing its local mobility, and also suppresses the tendency for the ions to aggregate. This polymer composite thus appears very promising for application in lithium ion batteries. PMID:12469813
Investigating fatty acids inserted into magnetically aligned phospholipid bilayers using EPR and solid-state NMR spectroscopy.
Nusair, Nisreen A; Tiburu, Elvis K; Dave, Paresh C; Lorigan, Gary A
This is the first time (2)H solid-state NMR spectroscopy and spin-labeled EPR spectroscopy have been utilized to probe the structural orientation and dynamics of a stearic acid incorporated into magnetically aligned phospholipid bilayers or bicelles. The data gleaned from the two different techniques provide a more complete description of the bilayer membrane system. Both methods provided similar qualitative information on the phospholipid bilayer, high order, and low motion for the hydrocarbon segment close to the carboxyl groups of the stearic acid and less order and more rapid motion at the end towards the terminal methyl groups. However, the segmental order parameters differed markedly due to the different orientations that the nitroxide and C-D bond axes transform with the various stearic acid acyl chain conformations, and because of the difference in dynamic sensitivity between NMR and EPR over the timescales examined. 5-, 7-, 12-, and 16-doxylstearic acids spin-labels were used in the EPR experiments and stearic acid-d(35) was used in the solid-state NMR experiments. The influence of the addition of cholesterol and the variation of temperature on the fatty acid hydrocarbon chain ordering in the DMPC/DHPC phospholipid bilayers was also studied. Cholesterol increased the degree of ordering of the hydrocarbon chains. Conversely, as the temperature of the magnetically aligned phospholipid bilayers increased, the order parameters decreased due to the higher random motion of the acyl chain of the stearic acid. The results indicate that magnetically aligned phospholipid bilayers are an excellent model membrane system and can be used for both NMR and EPR studies. PMID:15140432
An Investigation of Lanthanum Coordination Compounds by Using Solid- State 139La NMR Spectroscopy and Relativistic Density Functional Theory
Willans, Mathew J.; Feindel, Kirk W.; Ooms, Kristopher J.; Wasylishen, Roderick E.
Lanthanum-139 NMR spectra of stationary samples of several solid LaIII coordination compounds have been obtained at applied magnetic fields of 11.75 and 17.60 T. The breadth and shape of the 139La NMR spectra of the central transition are dominated by the interaction between the 139La nuclear quadrupole moment and the electric field gradient (EFG) at that nucleus; however, the influence of chemical-shift anisotropy on the NMR spectra is non-negligible for the majority of the compounds investigated. Analysis of the experimental NMR spectra reveals that the 139La quadrupolar coupling constants (CQ) range from 10.0 to 35.6 MHz, the spans of the chemical-shift tensor (W) range from 50 to 260 ppm, and the isotropic chemical shifts (diso) range from -80 to 178 ppm. In general, there is a correlation between the magnitudes of CQ and W, and diso is shown to depend on the La coordination number. Magnetic shielding tensors, calculated by using relativistic zeroth-order regular approximation density functional theory (ZORA-DFT) and incorporating scalar only or scalar plus spin-orbit relativistic effects, qualitatively reproduce the experimental chemical-shift tensors. In general, the inclusion of spin-orbit coupling yields results that are in better agreement with those from the experiment. The magnetic-shielding calculations and experimentally determined Euler angles can be used to predict the orientation of the chemical-shift and EFG tensors in the molecular frame. This study demonstrates that solid state 139La NMR spectroscopy is a useful characterization method and can provide insight into the molecular structure of lanthanum coordination compounds.
Probing the surface of platinum nanoparticles with 13CO by solid-state NMR and IR spectroscopies
NASA Astrophysics Data System (ADS)
Kinayyigit, Solen; Lara, Patricia; Lecante, Pierre; Philippot, Karine; Chaudret, Bruno
The synthesis and full characterization of platinum nanoparticles (Pt NPs) prepared by decomposition of the Pt(dba)2 complex in the presence of CO and H2 and stabilized either sterically by a polymer, polyvinylpyrrolidone or chemically by a ligand, diphenylphosphinobutane, are reported. In these studies, 13CO was used as a probe molecule to investigate the surface of the particles, using IR and solid-state NMR spectroscopies with magic angle spinning (MAS-NMR). Three nanosystems with different sizes are described: Pt/PVP/13CO (monomodal: 1.2 nm), Pt/dppb/13CO (bimodal: 1.2 nm and 2.0 nm) and Pt/dppb/H2 (monomodal: 2.0 nm) NPs. Spectroscopic data suggest a modification of the electronic state of the nanoparticles between 1.2 nm and 2.0 nm which can be related to the presence of Knight shift.The synthesis and full characterization of platinum nanoparticles (Pt NPs) prepared by decomposition of the Pt(dba)2 complex in the presence of CO and H2 and stabilized either sterically by a polymer, polyvinylpyrrolidone or chemically by a ligand, diphenylphosphinobutane, are reported. In these studies, 13CO was used as a probe molecule to investigate the surface of the particles, using IR and solid-state NMR spectroscopies with magic angle spinning (MAS-NMR). Three nanosystems with different sizes are described: Pt/PVP/13CO (monomodal: 1.2 nm), Pt/dppb/13CO (bimodal: 1.2 nm and 2.0 nm) and Pt/dppb/H2 (monomodal: 2.0 nm) NPs. Spectroscopic data suggest a modification of the electronic state of the nanoparticles between 1.2 nm and 2.0 nm which can be related to the presence of Knight shift. Electronic supplementary information (ESI) available: Synthesis of the Pt(dba)2 precursor, TEM images of Pt/PVP/H2 and Pt/dppb/13CO NPs, further results from WAXS studies, solution NMR spectra of Pt/dppb/13CO NPs and MAS-NMR spectra of Pt/dppb/13CO and Pt/dppb/H2 NPs at 260 K. See DOI: 10.1039c3nr03948j
"EASY: A simple tool for simultaneously removing background, deadtime and acoustic ringing in quantitative NMR spectroscopy. Part II: Improved ringing suppression, application to quadrupolar nuclei, cross polarisation and 2D NMR".
Jaeger, Christian; Hemmann, Felix
A simple experiment for Elimination of Artifacts in NMR SpectroscopY (EASY) was introduced in Part I, and it was shown that NMR probe background signals, spectral distortions due to deadtime effects, and acoustic ringing can be eliminated simultaneously from solid-state NMR spectra. In this Part II, it is shown that acoustic ringing suppression can be improved up to one order of magnitude compared to the original EASY pulse sequence by inserting a delay ? between the two data acquisition scans of the EASY pulse sequence. The achievable ringing suppression depends on the length of this delay and is limited by the spin-lattice relaxation time T1. Furthermore, EASY is considered in conjunction with NMR of quadrupolar nuclei. For strong second-order broadening, EASY can be used to acquire either pure central transition MAS patterns or pure satellite transition NMR spectra. Two further modifications to EASY are introduced. One concerns improved ringing artifact suppression in experiments in which the central transition NMR signal is amplified by Rotor Assisted Population Transfer (RAPT). The second EASY modification enables the acquisition of quantitative NMR spectra if signals with different quadrupole coupling constants are present. In addition, acoustic ringing and (11)B stator signals are removed. Finally, it is demonstrated that the basic idea of EASY for removing ringing artifacts can be realized for heteronuclear one-dimensional and hetero- and homo-nuclear multi-dimensional NMR experiments using extended phase cycling. (15)N{(1)H} CPMAS and (15)N 2D Exchange NMR spectroscopy are considered as examples. PMID:25200102
High resolution NMR spectroscopy of rat brain in vivo through indirect zero-quantum-coherence detection
NASA Astrophysics Data System (ADS)
de Graaf, Robin A.; Rothman, Douglas L.; Behar, Kevin L.
The time evolution of zero-quantum-coherences (ZQCs) is insensitive to magnetic field inhomogeneity. Using a 2D indirect ZQC detection method it is shown that high-resolution 1H NMR spectra can be obtained from rat brain in vivo at 11.74 T that are immune to magnetic field inhomogeneity. Simulations based on the density matrix formalism, as well as in vitro measurements are used to demonstrate the features of 2D ZQC NMR spectra. Unique spectral information which is normally not directly available from regular 1H NMR spectra can be extracted and used for compound identification or improved prior knowledge during spectral fitting.
High Resolution NMR Spectroscopy of Rat Brain In Vivo Through Indirect Zero-Quantum-Coherence Detection
de Graaf, Robin A.; Rothman, Douglas L.; Behar, Kevin L.
The time evolution of zero-quantum-coherences (ZQCs) is insensitive to magnetic field inhomogeneity. Using a 2D indirect ZQC detection method it is shown that high-resolution 1H NMR spectra can be obtained from rat brain in vivo at 11.74 T that are immune to magnetic field inhomogeneity. Simulations based on the density matrix formalism, as well as in vitro measurements are used to demonstrate the features of 2D ZQC NMR spectra. Unique spectral information which is normally not directly available from regular 1H NMR spectra can be extracted and used for compound identification or improved prior knowledge during spectral fitting. PMID:17587617
Probing phosphorylation by non-mammalian isoprenoid biosynthetic enzymes using 1H¢31P¢31P correlation NMR spectroscopyåć
Shah, Meha H.; Bitok, J. Kipchirchir; Hassis-LeBeau, Maria E.
The biogenesis of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) is accomplished by the methylerythritol phosphate (MEP) pathway in plants, bacteria and parasites, making it a potential target for the development of anti-infective agents and herbicides. The biosynthetic enzymes comprising this pathway catalyze intriguing chemical transformations on diphosphate scaffolds, offering an opportunity to generate novel analogs in this synthetically challenging compound class. Such a biosynthetic approach to generating new diphosphate analogs may involve transformation through discrete diphosphate species, presenting unique challenges in structure determination and characterization of unnatural enzyme-generated diphosphate products produced in tandem. We have developed 1H¢31P¢31P correlation NMR spectroscopy techniques for the direct characterization of crude MEP pathway enzyme products at low concentrations (200 ?M to 5 mM) on a room temperature (non-cryogenic) NMR probe. Coupling the 100% natural abundance of the 31P nucleus with the high intrinsic sensitivity of proton NMR, 1H¢31P¢31P correlation spectroscopy is particularly useful for characterization of unnatural diphosphate enzyme products in the MEP pathway. As proof of principle, we demonstrate the rapid characterization of natural enzyme products of the enzymes IspD, E and F in tandem enzyme incubations. In addition, we have characterized several unnatural enzyme products using this technique, including new products of cytidyltransferase IspD bearing erythritol, glycerol and ribose components. The results of this study indicate that IspD may be a useful biocatalyst and highlight 1H¢31P¢31P correlation spectroscopy as a valuable tool for the characterization of other unnatural products in non-mammalian isoprenoid biosynthesis. PMID:19668858
Studies on the interactions between glycosylated beta3-peptides and the lectin Vicia villosa by saturation transfer difference NMR spectroscopy.
Kaszowska, Marta; Norgren, Anna S; Arvidson, Per I; Sandstr÷m, Corine
Saturation transfer difference (STD) NMR spectroscopy was used to study the interaction of the lectin Vicia villosa (VVLB(4)) with alpha-D-GalNAc glycosylated beta(3)-peptides. The data were compared to those obtained with the monosaccharides D-Gal, D-GalNAc, and D-Glc as well as with those obtained with the Tn antigen alpha-glycopeptide (D-GalNAc-alpha-O-Ser/Thr), molecule naturally recognized by V. villosa. Evidence that the lectin also recognizes glycosylated beta(3)-peptides and has close contact with both the sugar and amino acid moieties was obtained. PMID:19863951
Aspects of the chemical structure of soil organic materials as revealed by solid-state 13 C NMR spectroscopy
J. A. Baldock; J. M. Oades; A. G. Waters; X. Peng; A. M. Vassallo; M. A. Wilson
Solid-state cross-polarisation\\/magic-angle-spinning3C nuclear magnetic resonance (CP\\/MAS13C NMR) spectroscopy was used to characterise semi-quantitatively the organic materials contained in particle size and density\\u000a fractions isolated from five different mineral soils: two Mollisols, two Oxisols and an Andosol. The acquired spectra were\\u000a analysed to determine the relative proportion of carboxyl, aromatic, O-alkyl and alkyl carbon contained in each fraction.\\u000a Although similar types
Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy of GNNQQNY Nanocrystals and Amyloid Fibrils
Debelouchina, Galia Tzvetanova
Dynamic nuclear polarization (DNP) utilizes the inherently larger polarization of electrons to enhance the sensitivity of conventional solid-state NMR experiments at low temperature. Recent advances in instrumentation ...
Long-Range Correlations between Aliphatic [superscript 13]C Nucleic in Protein MAS NMR Spectroscopy
Bayro, Marvin?J.
Highly efficient polarization transfer can be achieved in the magic-angle spinning NMR analysis of proteins by the combination of [superscript 13]C labeling at alternating positions and band-selective radio-frequency-driven ...
Recent developments and applications of saturation transfer difference nuclear magnetic resonance (STD NMR) spectroscopy.
Wagstaff, Jane L; Taylor, Samantha L; Howard, Mark J
This review aims to illustrate that STD NMR is not simply a method for drug screening and discovery, but has qualitative and quantitative applications that can answer fundamental and applied biological and biomedical questions involving molecular interactions between ligands and proteins. We begin with a basic introduction to the technique of STD NMR and report on recent advances and biological applications of STD including studies to follow the interactions of non-steroidal anti-inflammatories, minimum binding requirements for virus infection and understating inhibition of amyloid fibre formation. We expand on this introduction by reporting recent STD NMR studies of live-cell receptor systems, new methodologies using scanning STD, magic-angle spinning STD and approaches to use STD NMR in a quantitative fashion for dissociation constants and group epitope mapping (GEM) determination. We finish by outlining new approaches that have potential to influence future applications of the technique; NMR isotope-editing, heteronuclear multidimensional STD and (19)F STD methods that are becoming more amenable due to the latest NMR equipment technologies. PMID:23232937
Self contained high pressure cell, apparatus and procedure for the preparation of encapsulated proteins dissolved in low viscosity fluids for NMR spectroscopy
Peterson, Ronald W.; Wand, A. Joshua
The design of a sample cell for high performance nuclear magnetic resonance (NMR) at elevated pressure is described. The cell has been optimized for the study of encapsulated proteins dissolved in low viscosity fluids but is suitable for more general NMR spectroscopy of biomolecules at elevated pressure. The NMR cell is comprised of an alumina toughened zirconia tube mounted on a self-sealing non-magnetic metallic valve. The cell has several advantages including relatively low cost, excellent NMR performance, high pressure tolerance, chemical inertness and a relatively large active volume. Also described is a low volume sample preparation device which allows for the preparation of samples under high hydrostatic pressure and their subsequent transfer to the NMR cell. PMID:16508692
Analysis of immediate changes of water-soluble metabolites in alkali-burned rabbit cornea, aqueous humor and lens by high-resolution 1 H-NMR spectroscopy
žystein Risa; Oddbj°rn Sµther; Anna Midelfart; Jostein Krane; Jitka ?ejkovß
Purpose: To investigate immediate changes in water-soluble metabolites of ocular tissue in alkali-burned eyes by using high-resolution 1H-NMR spectroscopy. Methods: Adult New Zealand rabbit eyes were burned with 1 M NaOH for 1 min. Normal eyes were used as control. Samples from aqueous humor and perchloric acid extracts of the cornea and lens were analyzed on a NMR spectrometer operating
Determination of the structural changes by Raman and {sup 13}C CP/MAS NMR spectroscopy on native corn starch with plasticizers
Cozar, O. [Academy of Romanian Scientists, Splaiul Independentei 54, 050094, Bucharest, Romania and National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucure?ti - Cluj-Napoca Branch (Romania)] [Academy of Romanian Scientists, Splaiul Independentei 54, 050094, Bucharest, Romania and National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucure?ti - Cluj-Napoca Branch (Romania); Filip, C.; Tripon, C. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Cioica, N.; Co?a, C.; Nagy, E. M. [National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucure?ti - Cluj-Napoca Branch, RO-400458 Cluj-Napoca (Romania)] [National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry - INMA Bucure?ti - Cluj-Napoca Branch, RO-400458 Cluj-Napoca (Romania)
The plasticizing - antiplasticizing effect of water and glycerol contents on native corn starch samples is investigated by FT-Raman and {sup 13}C CP/MAS NMR spectroscopy. The presence of both amorphous and crystalline structural phases was evidenced in pure native corn starch and also in the samples containing plasticizers. Among the crystalline starch structures, the A- and V- types were suggested by CP/MAS NMR spectra.
Lipid analysis of human spermatozoa and seminal plasma by MALDI-TOF mass spectrometry and NMR spectroscopy Ś effects of freezing and thawing
J³rgen Schiller; J³rgen Arnhold; Hans-J³rgen Glander; Klaus Arnold
In the present study, the applicability of proton NMR spectroscopy and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) to the analysis of the lipid composition of human spermatozoa and seminal fluids as well as changes after cryopreservation of human spermatozoa was investigated. Whereas NMR spectra primarily indicated a high content of double bonds within the spermatozoa but
Quality assessment in in vivo NMR spectroscopy: IV. A multicentre trial of test objects and protocols for performance assessment in clinical NMR spectroscopy
S. F. Keevil; B. Barbiroli; D. J. Collins; E. R. Danielsen; J. Hennig; O. Henriksen; M. O. Leach; R. Longo; M. Lowry; C. Moore; E. Moser; C. Segebarth; W. M. M. J. Bovee; F. Podo
A multicentre trial of test objects and protocols for performance assessment in single volume and slice selective magnetic resonance spectroscopy (MRS) was conducted by the European Community Concerted Action on MRI and MRS. The trial assessed phosphorus and proton localisation techniques implemented on commercially available MR systems at ten sites in Europe. At each site, a number of parameters devised
In-situ annotation of carbohydrate diversity, abundance, and degradability in highly complex mixtures using NMR spectroscopy.
Meier, Sebastian
Many functions of carbohydrates depend on the detection of short structural motifs, approximately up to hexasaccharide length, by receptors or catalysts. This study investigates the usefulness of state-of-the-art (1)H-(13)C nuclear-magnetic-resonance (NMR) spectroscopy for characterizing the diversity, abundance, and degradability of such short structural motifs in plant-derived carbohydrates. Assignments of carbohydrate signals for (1)H-(13)C NMR spectra of beer, wine, and fruit juice yield up to >130 assignments in situ, i.e. in individual samples without separation or derivatization. More than 500 structural motifs can be resolved over a concentration range of ~10(3)Āin experiments of a few hours duration. The diversity of carbohydrate units increases according to power laws at lower concentrations for both cereal and fruit-derived samples. Simple graphs resolve the smaller overall contribution of more diverse but less abundant motifs to carbohydrate biomass. Susceptibility to enzymatic degradation is probed simultaneously for hundreds of structural motifs to reduce uncertainties in the identification of motifs and to probe enzyme specificity with assigned motifs. Several properties of fundamental biotechnological importance can thus be assessed in situ by heteronuclear NMR methods. PMID:25342297
Multinuclear nanoliter one-dimensional and two-dimensional NMR spectroscopy with a single non-resonant microcoil
NASA Astrophysics Data System (ADS)
Fratila, Raluca M.; Gomez, M. Victoria; S²kora, Stanislav; Velders, Aldrik H.
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique, but its low sensitivity and highly sophisticated, costly, equipment severely constrain more widespread applications. Here we show that a non-resonant planar transceiver microcoil integrated in a microfluidic chip (detection volume 25?nl) can detect different nuclides in the full broad-band range of Larmor frequencies (at 9.4?T from 61 to 400?MHz). Routine one-dimensional (1D) and two-dimensional (2D), homo- and heteronuclear experiments can be carried out using the broad-band coil set-up. Noteworthy, heteronuclear 2D experiments can be performed in a straightforward manner on virtually any combination of nuclides (from classical 1H-13C to more exotic combinations like 19F-31P) both in coupled and decoupled mode. Importantly, the concept of a non-resonant system provides magnetic field-independent NMR probes; moreover, the small-volume alleviates problems related to field inhomogeneity, making the broad-band coil an attractive option for, for example, portable and table-top NMR systems.
Multinuclear nanoliter one-dimensional and two-dimensional NMR spectroscopy with a single non-resonant microcoil.
Fratila, Raluca M; Gomez, M Victoria; S²kora, Stanislav; Velders, Aldrik H
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique, but its low sensitivity and highly sophisticated, costly, equipment severely constrain more widespread applications. Here we show that a non-resonant planar transceiver microcoil integrated in a microfluidic chip (detection volume 25?nl) can detect different nuclides in the full broad-band range of Larmor frequencies (at 9.4?T from 61 to 400?MHz). Routine one-dimensional (1D) and two-dimensional (2D), homo- and heteronuclear experiments can be carried out using the broad-band coil set-up. Noteworthy, heteronuclear 2D experiments can be performed in a straightforward manner on virtually any combination of nuclides (from classical ╣H-╣│C to more exotic combinations like ╣?F-│╣P) both in coupled and decoupled mode. Importantly, the concept of a non-resonant system provides magnetic field-independent NMR probes; moreover, the small-volume alleviates problems related to field inhomogeneity, making the broad-band coil an attractive option for, for example, portable and table-top NMR systems. PMID:24394755
Analysis of monoglycerides, diglycerides, sterols, and free fatty acids in coconut (Cocos nucifera L.) oil by 31P NMR spectroscopy.
Dayrit, Fabian M; Buenafe, Olivia Erin M; Chainani, Edward T; de Vera, Ian Mitchelle S
Phosphorus-31 nuclear magnetic resonance spectroscopy ( (31)P NMR) was used to differentiate virgin coconut oil (VCO) from refined, bleached, deodorized coconut oil (RCO). Monoglycerides (MGs), diglycerides (DGs), sterols, and free fatty acids (FFAs) in VCO and RCO were converted into dioxaphospholane derivatives and analyzed by (31)P NMR. On the average, 1-MG was found to be higher in VCO (0.027%) than RCO (0.019%). 2-MG was not detected in any of the samples down to a detection limit of 0.014%. On the average, total DGs were lower in VCO (1.55%) than RCO (4.10%). When plotted in terms of the ratio [1,2-DG/total DGs] versus total DGs, VCO and RCO samples grouped separately. Total sterols were higher in VCO (0.096%) compared with RCO (0.032%), and the FFA content was 8 times higher in VCO than RCO (0.127% vs 0.015%). FFA determination by (31)P NMR and titration gave comparable results. Principal components analysis shows that the 1,2-DG, 1,3-DG, and FFAs are the most important parameters for differentiating VCO from RCO. PMID:18576656
Hydration properties of regioselectively etherified celluloses monitored by 2H and 13C solid-state MAS NMR spectroscopy.
Larsen, Flemming H; Sch÷bitz, Michael; Schaller, Jens
The hydration properties of 2,3-O-hydroxypropylcellulose (HPC) and 2,3-O-hydroxyethylcellulose (HEC) were analyzed by multi-nuclear solid-state MAS NMR spectroscopy. By 13C single-pulse (SP) MAS and cross-polarization (CP) MAS NMR, differences between the immobile regions and all parts of the polysaccharides were detected as a function of hydration. Complementary information about the water environments was observed by 2H MAS NMR. By this approach it was demonstrated that side chains in 2,3-O-HPC and 2,3-O-HEC were easier to hydrate than the cellulose backbone. Furthermore the motion of water was more restricted (slower) in 2,3-O-HPC than in 2,3-O-HEC. For both polysaccharides the hydration could be explained by a two-step process: in step one increased ordering of the immobile regions occurs after which the entire polymer is hydrated in step two. PMID:24750769
Characterization of bio-oil from hydrothermal liquefaction of organic waste by NMR spectroscopy and FTICR mass spectrometry.
Leonardis, Irene; Chiaberge, Stefano; Fiorani, Tiziana; Spera, Silvia; Battistel, Ezio; Bosetti, Aldo; Cesti, Pietro; Reale, Samantha; De Angelis, Francesco
Solid wastes of organic origins are potential feedstocks for the production of liquid biofuels, which could be suitable alternatives to fossil fuels for the transport and heating sectors, as well as for industrial use. By hydrothermal liquefaction, the wet biomass is partially transformed into a water-immiscible, oil-like organic matter called bio-oil. In this study, an integrated NMR spectroscopy/mass spectrometry approach has been developed for the characterization of the hydrothermal liquefaction of bio-oil at the molecular level. (1)H and (13)C NMR spectroscopy were used for the identification of functional groups and gauging the aromatic carbon content in the mixture. GC-MS analysis revealed that the volatile fraction was rich in fatty acids, as well as in amides and esters. High-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been applied in a systematic way to fully categorize the bio-oil in terms of different classes of components, according to their molecular formulas. Most importantly, for the first time, by using this technique, and for the liquefaction bio-oil characterization in particular, FT-MS data have been used to develop a methodology for the determination of the aromatic versus aliphatic carbon and nitrogen content. It is well known that, because they resist hydrogenation and represent sources of polluting species, both aromatic molecules and nitrogen-containing species raise concerns for subsequent upgrading of bio-oil into a diesel-like fuel. PMID:23139164
Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy.
Houston, Jacqueline R; Maxwell, Robert S; Carroll, Susan A
Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline calcium (alumino-)silicate hydrate (Al-CSH) forms as a precursor solid to the cement mineral tobermorite. Rate constants for tobermorite growth were found to be k = 0.6 (+/- 0.1) x 10(-5) s(-1) for a solution:solid of 10:1 and 1.6 (+/- 0.8) x 10(-4) s(-1) for a solution:solid of 5:1 (batch mode; T = 150 degrees C). This data indicates that reaction rates for tobermorite growth are faster when the solution volume is reduced by half, suggesting that rates are dependent on solution saturation and that the Gibbs free energy is the reaction driver. However, calculated solution saturation indexes for Al-CSH and tobermorite differ by less than one log unit, which is within the measured uncertainty. Based on this data, we consider both heterogeneous nucleation as the thermodynamic driver and internal restructuring as possible mechanistic pathways for growth. We also use NMR spectroscopy to characterize the site symmetry and bonding environment of Al and Si in a reacted tobermorite sample. We find two [4]Al coordination structures at delta iso = 59.9 ppm and 66.3 ppm with quadrupolar product parameters (PQ) of 0.21 MHz and 0.10 MHz (+/- 0.08) from 27Al 3Q-MAS NMR and speculate on the Al occupancy of framework sites by probing the protonation environment of Al metal centers using 27Al{1H}CP-MAS NMR. PMID:19144195
An active photoreceptor intermediate revealed by in situ photoirradiated solid-state NMR spectroscopy.
Tomonaga, Yuya; Hidaka, Tetsurou; Kawamura, Izuru; Nishio, Takudo; Ohsawa, Kazuhiro; Okitsu, Takashi; Wada, Akimori; Sudo, Yuki; Kamo, Naoki; Ramamoorthy, Ayyalusamy; Naito, Akira
A novel, to our knowledge, inĀsitu photoirradiation system for solid-state NMR measurements is improved and demonstrated to successfully identify the M-photointermediate of pharaonis phoborhodopsin (ppR or sensory rhodopsin II), that of the complex with transducer (ppR/pHtrII), and T204A mutant embedded in a model membrane. The (13)C NMR signals from [20-(13)C]retinal-ppR and ppR/pHtrII revealed that multiple M-intermediates with 13-cis, 15-anti retinal configuration coexisted under the continuously photoirradiated condition. NMR signals observed from the photoactivated retinal provide insights into the process of photocycle in the ppR/pHtrII complex. PMID:22098758
Permanent Magnet with Very Low Field Gradient (0.1G/mm) for NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Ilic, Ognjen; Issadore, David; Hunt, Tom; Westervelt, Robert
Nuclear Magnetic Resonance (NMR) is a powerful analytical tool for obtaining chemical, physical and structural information. To produce the uniform fields required, NMR experiments typically employ large, expensive electromagnets and shimming coils. We have developed a small permanent magnet with an iron yoke that produces a field of ś10 kG with gradient < 0.1G/mm across a 6 mm region for a total field homogeneity of 10 ppm. The system consists of two parallel cylindrical NdFe permanent magnets, 50mm in diameter and 25mm thick, separated by 4mm. The magnets are surrounded by hollow low-carbon steel cylinders with steel caps on each end of the yoke. By adjusting the distance between the yoke caps and the magnet we cancel first-order field strength variations, as shown in simulations. This design is an important innovation for low cost, benchtop NMR systems. *Supported by the NCI MIT-Harvard CCNE.
Intermolecular Interactions between Eosin Y and Caffeine Using (1)H-NMR Spectroscopy.
Okuom, Macduff O; Wilson, Mark V; Jackson, Abby; Holmes, Andrea E
DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using (1)H-NMR, (1)H-COSY, and (1)H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772
Fragment based drug discovery: practical implementation based on ╣?F NMR spectroscopy.
Jordan, John B; Poppe, Leszek; Xia, Xiaoyang; Cheng, Alan C; Sun, Yax; Michelsen, Klaus; Eastwood, Heather; Schnier, Paul D; Nixey, Thomas; Zhong, Wenge
Fragment based drug discovery (FBDD) is a widely used tool for discovering novel therapeutics. NMR is a powerful means for implementing FBDD, and several approaches have been proposed utilizing (1)H-(15)N heteronuclear single quantum coherence (HSQC) as well as one-dimensional (1)H and (19)F NMR to screen compound mixtures against a target of interest. While proton-based NMR methods of fragment screening (FBS) have been well documented and are widely used, the use of (19)F detection in FBS has been only recently introduced (Vulpetti et al. J. Am. Chem. Soc.2009, 131 (36), 12949-12959) with the aim of targeting "fluorophilic" sites in proteins. Here, we demonstrate a more general use of (19)F NMR-based fragment screening in several areas: as a key tool for rapid and sensitive detection of fragment hits, as a method for the rapid development of structure-activity relationship (SAR) on the hit-to-lead path using in-house libraries and/or commercially available compounds, and as a quick and efficient means of assessing target druggability. PMID:22165820
Multiphoton NMR spectroscopy on a spin system with I=1\\/2
Y. Zur; M. H. Levitt; S. Vega
Multiple quantum effects in double frequency (df) pulsed NMR experiments on multilevel spin systems are studied. In these experiments, the spin systems are irradiated by two rf fields, applied simultaneously. A general theoretical description of these experiments is presented using the theory of Shirley for time dependent Hamiltonians. Multiphoton resonance conditions are given and time independent fictitious spin-1\\/2 Hamiltonians are
Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies
ERIC Educational Resources Information Center
Schenck, Heather L.; Hui, KaWai
These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). Theģ
Stereoregularity evolution of methyl acrylate and vinyl acetate copolymers by 2D NMR spectroscopy
NASA Astrophysics Data System (ADS)
Brar, A. S.; Goyal, Ashok Kumar; Ganai, Anal; Hooda, Sunita
Copolymers of methyl acrylate (M) and vinyl acetate (V) were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator at 70 ░C and their composition were calculated from 1H NMR spectra. These copolymer compositions were further used to calculate reactivity ratios of V/M copolymers. The reactivity ratios obtained from linear Kelen-Tudos (KT) and non-linear error-in-variable methods (EVM) are rM = 6.74 ▒ 1.03, rV = 0.04 ▒ 0.01 and rM = 6.72, rV = 0.04, respectively. The copolymers were analyzed for their stereochemical structure utilizing various 1D ( 1H, 13C{ 1H}, DEPT) and 2D (HSQC, TOCSY, HMBC) NMR techniques. 2D HSQC and TOCSY NMR experiments were employed to resolve the highly overlapped and complex 1H and 13C{ 1H} NMR spectra of copolymers. The complete spectral assignment of carbonyl carbons were done with the help of 2D HMBC spectra. The carbonyl carbon was found to be sensitive up to pentad configurational sequences and shows three and four bond couplings with methine and methylene protons.
New developments in isotope labeling strategies for protein solution NMR spectroscopy
Natalie K Goto; Lewis E Kay
The development of novel isotope labeling strategies for proteins has facilitated the study of the structure and dynamics of these molecules. In addition, the recent emergence of alternative methods of bacterial expression for obtaining isotopically labeled proteins permits the study of new classes of important proteins by solution NMR methods.
In Situ NMR Spectroscopy of Supercapacitors: Insight into the Charge Storage Mechanism
Electrochemical capacitors, commonly known as supercapacitors, are important energy storage devices with high power capabilities and long cycle lives. Here we report the development and application of in situ nuclear magnetic resonance (NMR) methodologies to study changes at the electrode¢electrolyte interface in working devices as they charge and discharge. For a supercapacitor comprising activated carbon electrodes and an organic electrolyte, NMR experiments carried out at different charge states allow quantification of the number of charge storing species and show that there are at least two distinct charge storage regimes. At cell voltages below 0.75 V, electrolyte anions are increasingly desorbed from the carbon micropores at the negative electrode, while at the positive electrode there is little change in the number of anions that are adsorbed as the voltage is increased. However, above a cell voltage of 0.75 V, dramatic increases in the amount of adsorbed anions in the positive electrode are observed while anions continue to be desorbed at the negative electrode. NMR experiments with simultaneous cyclic voltammetry show that supercapacitor charging causes marked changes to the local environments of charge storing species, with periodic changes of their chemical shift observed. NMR calculations on a model carbon fragment show that the addition and removal of electrons from a delocalized system should lead to considerable increases in the nucleus-independent chemical shift of nearby species, in agreement with our experimental observations. PMID:24274637
Comprehensive multiphase NMR spectroscopy: Basic experimental approaches to differentiate phases in heterogeneous samples
NASA Astrophysics Data System (ADS)
Courtier-Murias, Denis; Farooq, Hashim; Masoom, Hussain; Botana, Adolfo; Soong, Ronald; Longstaffe, James G.; Simpson, Myrna J.; Maas, Werner E.; Fey, Michael; Andrew, Brian; Struppe, Jochem; Hutchins, Howard; Krishnamurthy, Sridevi; Kumar, Rajeev; Monette, Martine; Stronks, Henry J.; Hume, Alan; Simpson, Andrķ J.
Heterogeneous samples, such as soils, sediments, plants, tissues, foods and organisms, often contain liquid-, gel- and solid-like phases and it is the synergism between these phases that determine their environmental and biological properties. Studying each phase separately can perturb the sample, removing important structural information such as chemical interactions at the gel-solid interface, kinetics across boundaries and conformation in the natural state. In order to overcome these limitations a Comprehensive Multiphase-Nuclear Magnetic Resonance (CMP-NMR) probe has been developed, and is introduced here, that permits all bonds in all phases to be studied and differentiated in whole unaltered natural samples. The CMP-NMR probe is built with high power circuitry, Magic Angle Spinning (MAS), is fitted with a lock channel, pulse field gradients, and is fully susceptibility matched. Consequently, this novel NMR probe has to cover all HR-MAS aspects without compromising power handling to permit the full range of solution-, gel- and solid-state experiments available today. Using this technology, both structures and interactions can be studied independently in each phase as well as transfer/interactions between phases within a heterogeneous sample. This paper outlines some basic experimental approaches using a model heterogeneous multiphase sample containing liquid-, gel- and solid-like components in water, yielding separate 1H and 13C spectra for the different phases. In addition, 19F performance is also addressed. To illustrate the capability of 19F NMR soil samples, containing two different contaminants, are used, demonstrating a preliminary, but real-world application of this technology. This novel NMR approach possesses a great potential for the in situ study of natural samples in their native state.
Simultaneous Structural Identification of Natural Products in Fractions of Crude Extract of the Rare Endangered Plant Anoectochilus roxburghii Using 1H NMR/RRLC-MS Parallel Dynamic Spectroscopy
Wang, Xiao-Xue; He, Jiu-Ming; Wang, Chun-Lan; Zhang, Rui-Ping; He, Wen-Yi; Guo, Shun-Xing; Sun, Rui-Xiang; Abliz, Zeper
Nuclear magnetic resonance/liquid chromatography-mass spectroscopy parallel dynamic spectroscopy (NMR/LC-MS PDS) is a method aimed at the simultaneous structural identification of natural products in complex mixtures. In this study, the method is illustrated with respect to 1H NMR and rapid resolution liquid chromatography-mass spectroscopy (RRLC-MS) data, acquired from the crude extract of Anoectochilus roxburghii, which was separated into a series of fractions with the concentration of constituent dynamic variation using reversed-phase preparative chromatography. Through fraction ranges and intensity changing profiles in 1H NMR/RRLC¢MS PDS spectrum, 1H NMR and the extracted ion chromatogram (XIC) signals deriving from the same individual constituent, were correlated due to the signal amplitude co-variation resulting from the concentration variation of constituents in a series of incompletely separated fractions. 1H NMR/RRLC-MS PDS was then successfully used to identify three types of natural products, including eight flavonoids, four organic acids and p-hydroxybenzaldehyde, five of which have not previously been reported in Anoectochilus roxburghii. In addition, two groups of co-eluted compounds were successfully identified. The results prove that this approach should be of benefit in the unequivocal structural determination of a variety of classes of compounds from extremely complex mixtures, such as herbs and biological samples, which will lead to improved efficiency in the identification of new potential lead compounds. PMID:21731458
Characterization of polysulfone and polysulfone/vanillin microcapsules by 1H NMR spectroscopy, solid-state 13C CP/MAS-NMR spectroscopy, and N2 adsorption-desorption analyses.
Pe±a, Brisa; de Mķnorval, Louis-Charles; Garcia-Valls, Ricard; GumĒ, TÓnia
Textile detergent and softener industries have incorporated perfume microencapsulation technology to improve their products. Perfume encapsulation allows perfume protection until use and provides a long-lasting fragrance release. But, certain industrial microcapsules show low encapsulation capacity and low material stability. Polysulfone capsules have been already proposed to solve these drawbacks. Among them, PSf/Vanillin capsules were considered as a desirable system. They present both good material stability and high encapsulation capacity. However, several factors such as the final location of the perfume in the polymeric matrix, the aggregation state that it has in the capsule and its interaction with the capsule components have not been studied yet. These factors can provide vast information about the capsule performance and its improvement. With the aim to characterize these parameters, the physical and chemical properties of PSf/Vanillin capsules have been investigated by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and N(2) adsorption-desorption measurements. AFM micrograph and N(2) isotherms confirm that the presence of vanillin modify the physical structure of PSf/Vanillin microcapsules as it is trapped in the capsule porosity. NMR results show that vanillin is present in solid state in PSf/Vanillin microcapsules. PMID:22008282
Symbiosis between in vivo and in vitro NMR spectroscopy: The creatine, N-acetylaspartate, glutamate, and GABA content of the epileptic human brain
Ognen A. C. Petroff; Lisa A. Pleban; Dennis D. Spencer
High resolution 1H NMR spectroscopy was used to analyze temporal lobe biopsies obtained from patients with epilepsy. Heat-stabilized cerebrum, dialyzed cytosolic macromolecules, and perchloric acid extracts were studied using one- and two dimensional spectroscopy. Anterior temporal lobe neocortex was enriched in GABA, glutamate, alanine, N-acetylaspartate, and creatine. Subjacent white matter was enriched in aspartate, glutamine, and inositol. The N-acetylaspartate\\/creatine mole
╣H- and ╣│C-NMR spectroscopy of Thy-1-APPSL mice brain extracts indicates metabolic changes in Alzheimer's disease.
Doert, A; Pilatus, U; Zanella, F; M³ller, W E; Eckert, G P
Biochemical alterations underlying the symptoms and pathomechanisms of Alzheimer's disease (AD) are not fully understood. However, alterations of glucose metabolism and mitochondrial dysfunction certainly play an important role. (1)H- and (13)C-NMR spectroscopy exhibits promising results in providing information about those alterations in vivo in patients and animals, especially regarding the mitochondrial tricarboxylic acid (TCA) cycle. Accordingly, transgenic mice expressing mutant human amyloid precursor protein (APP(SL))-serving as a model of neuropathological changes in AD-were examined with in vitro 1D (1)H- and 2D (1)H-(13)C-HSQC-NMR spectroscopy after oral administration of 1-(13)C-glucose and acquisition of brain material after 30 min. Perchloric acid extracts were measured using a 500 MHz spectrometer, providing more detailed information compared to in vivo spectra achievable nowadays. Area under curve (AUC) data of metabolite peaks were obtained and normalized in relation to the creatine signal, serving as internal reference. Besides confirming well-known metabolic alterations in AD like decreased N-acetylaspartate (NAA)/Creatine (Cr) ratio, new findings such as a decrease in phosphorylcholine (PC) are presented. Glutamate (Glu) and glutamine (Gln) concentrations were decreased while ?-aminobutyric acid (GABA) was elevated in Thy1-APP(SL) mice. (13)C-NMR spectroscopy revealed a shift in the Glx-2/Glx-4-ratio-where Glx represents a combined Glu/Gln-signal-towards Glx-2 in AD. These findings correlated well with the NAA/Cr-ratio. The Gln-4/Glu-4-ratio is altered in favor of Glu. Our findings suggest that glutamine synthetase (GS), which is predominantly present in glial cells may be impaired in the brain of Thy1-APP(SL) transgenic mice. Since GS is an ATP-dependent enzyme, mitochondrial dysfunction might contribute to reduced activity, which might also account for the increased metabolism of glutamate via the GABA shunt, a metabolic pathway to bypass intra-mitochondrial ?-ketoglutarate-dehydrogenase, resulting in elevated GABA levels. PMID:25742870
Two-dimensional NMR spectroscopy links structural moieties of soil organic matter to the temperature sensitivity of its decomposition
NASA Astrophysics Data System (ADS)
Soucemarianadin, Laure; Erhagen, Bj÷rn; ųquist, Mats; Nilsson, Mats; Schleucher, J³rgen
Soil organic matter (SOM) represents a huge carbon pool, specifically in boreal ecosystems. Warming-induced release of large amounts of CO2 from the soil carbon pool might become a significant exacerbating feedback to global warming, if decomposition rates of boreal soils were more sensitive to increased temperatures. Despite a large number of studies dedicated to the topic, it has proven difficult to elucidate how the organo-chemical composition of SOM influences its decomposition, or its quality as a substrate for microbial metabolism. A great part of this challenge results from our inability to achieve a detailed characterization of the complex composition of SOM on the level of molecular structural moieties. 13C nuclear magnetic resonance (NMR) spectroscopy is a common tool to characterize SOM. However, SOM is a very complex mixture and the chemical shift regions distinguished in the 13C NMR spectra often represent many different molecular fragments. For example, in the carbohydrates region, signals of all monosaccharides present in many different polymers overlap. This overlap thwarts attempts to identify molecular moieties, resulting in insufficient information to characterize SOM composition. We applied two-dimensional (2D) NMR to characterize SOM with highly increased resolution. We directly dissolved finely ground litters and forest floors'fibric and humic horizons'of both coniferous and deciduous boreal forests in dimethyl sulfoxide and analyzed the resulting solution with a 2D 1H-13C NMR experiment. In the 2D planes of these spectra, signals of CH groups can be resolved based on their 13C and 1H chemical shifts, hence the resolving power and information content of these NMR spectra is hugely increased. The 2D spectra indeed resolved overlaps observed in 1D 13C spectra, so that hundreds of distinct CH groups could be observed and many molecular fragments could be identified. For instance, in the aromatics region, signals from individual lignin units could be recognized. It was hence possible to follow the fate of specific structural moieties in soils. We observed differences between litter and soil samples, and were able to relate them to the decomposition of identifiable moieties. Using multivariate data analysis, we aimed at linking the detailed chemical fingerprints of SOM to turnover rates in a soil incubation experiment. With the multivariate models, we were able to relate signal patterns in the 2D spectra and intensities of identifiable molecular moieties to variability in the temperature response of organic matter decomposition, as assessed by Q10. In conclusion, the characterization of SOM composition at the molecular level by solution-state 2D NMR spectroscopy is highly promising; it offers unprecedented possibilities to link SOM molecular composition to ecosystem processes, and their responses to environmental changes.
Chemical structures of swine-manure chars produced under different carbonization conditions investigated by advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
Two types of swine manure chars, hydrothermally-produced hydrochar and slow-pyrolysis pyrochar, and their raw swine manure solid were characterized using advanced 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. Compared with the parent raw swine manure, both hydrochars and pyrochar di...
Effect of sugars and sugar alcohols on freezing behavior of corn starch gel as monitored by time domain 1H NMR spectroscopy
Y.-R. Kim; B.-S. Yoo; P. Cornillon; S.-T. Lim
The freezing behavior of corn starch gels (40% starch solids) with 11 different sugars and sugar alcohols (10 or 30% based on starch weight) was investigated using time domain 1H NMR spectroscopy. As estimated from the liquid signal intensity curve, the ice melting temperature linearly decreased and the relative amount of solid glass formed increased with the molar concentration of
Structural studies of proteins by paramagnetic solid-state NMR spectroscopy
NASA Astrophysics Data System (ADS)
Jaroniec, Christopher P.
Paramagnetism-based nuclear pseudocontact shifts and spin relaxation enhancements contain a wealth of information in solid-state NMR spectra about electron-nucleus distances on the ?20 ┼ length scale, far beyond that normally probed through measurements of nuclear dipolar couplings. Such data are especially vital in the context of structural studies of proteins and other biological molecules that suffer from a sparse number of experimentally-accessible atomic distances constraining their three-dimensional fold or intermolecular interactions. This perspective provides a brief overview of the recent developments and applications of paramagnetic magic-angle spinning NMR to biological systems, with primary focus on the investigations of metalloproteins and natively diamagnetic proteins modified with covalent paramagnetic tags.
Structure determination of the seven-helical transmembrane receptor sensory rhodopsin II by solution NMR spectroscopy
Gautier, Antoine; Mott, Helen R.; Bostock, Mark J.; Kirkpatrick, John P.; Nietlispach, Daniel
Seven-helical membrane proteins represent a challenge for structural biology. Here, we report the first NMR structure determination of a detergent-solubilized seven-helical transmembrane (7TM) protein, the phototaxis receptor sensory rhodopsin II (pSRII) from Natronomonas pharaonis, as a proof of principle. The overall quality of the structure ensemble is extremely good (backbone root mean squared deviation of 0.48 ┼) and agrees well with previously determined X-ray structures. Furthermore, measurements in more native-like small phospholipid bicelles indicate that the protein structure is the same as in detergent micelles, suggesting that environment specific effects are minimal when using mild detergents. We use our case study as a platform to discuss the feasibility of similar solution NMR studies for other 7TM proteins including members of the family of G protein-coupled receptors (GPCRs). PMID:20512150
Mechanism for microwave heating of 1-(4?-cyanophenyl)-4-propylcyclohexane characterized by in situ microwave irradiation NMR spectroscopy
NASA Astrophysics Data System (ADS)
Tasei, Yugo; Yamakami, Takuya; Kawamura, Izuru; Fujito, Teruaki; Ushida, Kiminori; Sato, Motoyasu; Naito, Akira
Microwave heating is widely used to accelerate organic reactions and enhance the activity of enzymes. However, the detailed molecular mechanism for the effect of microwave on chemical reactions is not yet fully understood. To investigate the effects of microwave heating on organic compounds, we have developed an in situ microwave irradiation NMR spectroscopy. 1H NMR spectra of 1-(4?-cyanophenyl)-4-propylcyclohexane (PCH3) in the liquid crystalline and isotropic phases were observed under microwave irradiation. When the temperature was regulated at slightly higher than the phase transition temperature (Tc = 45 ░C) under a gas flow temperature control system, liquid crystalline phase mostly changed to the isotropic phase. Under microwave irradiation and with the gas flow temperature maintained at 20 ░C, which is 25 ░C below the Tc, the isotropic phase appeared stationary as an approximately 2% fraction in the liquid crystalline phase. The temperature of the liquid crystalline state was estimated to be 38 ░C according to the line width, which is at least 7 ░C lower than the Tc. The temperature of this isotropic phase should be higher than 45 ░C, which is considered to be a non-equilibrium local heating state induced by microwave irradiation. Microwaves at a power of 195 W were irradiated to the isotropic phase of PCH3 at 50 ░C and after 2 min, the temperature reached 220 ░C. The temperature of PCH3 under microwave irradiation was estimated by measurement of the chemical shift changes of individual protons in the molecule. These results demonstrate that microwave heating generates very high temperature within a short time using an in situ microwave irradiation NMR spectrometer.
A solid-state 55Mn NMR spectroscopy and DFT investigation of manganese pentacarbonyl compounds
Feindel, Kirk W.; Ooms, Kristopher J.; Wasylishen, Roderick E.
Central transition 55Mn NMR spectra of several solid manganese pentacarbonyls acquired at magnetic field strengths of 11.75, 17.63, and 21.1 T are presented. The variety of distinct powder sample lineshapes obtained demonstrates the sensitivity of solid-state 55Mn NMR to the local bonding environment, including the presence of crystallographically unique Mn sites, and facilitates the extraction of the Mn chemical shift anisotropies, CSAs, and the nuclear quadrupolar parameters. The compounds investigated include molecules with approximate C4v symmetry, LMn(CO)5 (L ╝ Cl, Br, I, HgMn(CO)5, CH3) and several molecules of lower symmetry (L ╝ PhCH2, Ph3*nClnSn (n ╝ 1, 2, 3)). For these compounds, the Mn CSA values range from o100 ppm for Cl3SnMn(CO)5 to 1260 ppm for ClMn(CO)5. At 21.1 T the 55Mn NMR lineshapes are appreciably influenced by the Mn CSA despite the presence of significant 55Mn quadrupolar coupling constants that range from 8.0 MHz for Cl3SnMn(CO)5 to 35.0 MHz for CH3Mn(CO)5. The breadth of the solid-state 55Mn NMR spectra of the pentacarbonyl halides is dominated by the CSA at all three applied magnetic fields. DFT calculations of the Mn magnetic shielding tensors reproduce the experimental trends and the magnitude of the CSA is qualitatively rationalized using a molecular orbital, MO, interpretation based on RamseyÆs theory of magnetic shielding. In addition to the energy differences between symmetry-appropriate occupied and virtual MOs, the d-character of the Mn MOs is important for determining the paramagnetic shielding contribution to the principal components of the magnetic shielding tensor.
Gradient-tailored excitation for single-quantum NMR spectroscopy of aqueous solutions
Martial Piotto; Vladimir Saudek; Vladimir Sklenß?
Summary A novel approach to tailored selective excitation for the measurement of NMR spectra in non-deuterated aqueous solutions (WATERGATE, WATER suppression by GraAdient-Tailored Excitation) is described. The gradient echo sequence, which effectively combines one selective 180░ radiofrequency pulse and two field gradient pulses, achieves highly selective and effective water suppression. This technique is ideally suited for the rapid collection of
Isotope labeling strategies for the study of high-molecular-weight proteins by solution NMR spectroscopy
Vitali Tugarinov; Voula Kanelis; Lewis E Kay
The development of isotope labeling methodology has had a significant impact on NMR studies of high-molecular-weight proteins and macromolecular complexes. Here we review some of this methodology that has been developed and used in our laboratory. In particular, experimental protocols are described for the production of highly deuterated, uniformly 15N- and 13C-labeled samples of large proteins, with optional incorporation of
Total assignment and structure in solution of tetrandrine by NMR spectroscopy and molecular modelling
NASA Astrophysics Data System (ADS)
Thevand, Andrķ; Stanculescu, Ioana; Mandravel, Cristina; Woisel, Patrice; Surpateanu, Gheorghe
High-resolution 1- and 2D NMR spectra of tetrandrine and molecular modelling were employed to characterise its structure in solution. Complete and unambiguous assignment of all proton and carbon resonance signals is reported. Scalar couplings were determined from dihedral angles with the Karplus equation. Inter-proton distances were evaluated from NOE correlation peaks. Comparison of simulated and X-ray conformations of tetrandrine reveals only small differences.
Magneto-optical contrast in liquid-state optically detected NMR spectroscopy
Pagliero, Daniela; Meriles, Carlos A.
We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids. Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems. PMID:22100736
Magneto-optical contrast in liquid-state optically detected NMR spectroscopy.
Pagliero, Daniela; Meriles, Carlos A
We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids. Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems. PMID:22100736
Metabolomic Investigations of American Oysters Using 1H-NMR Spectroscopy
Tikunov, Andrey P.; Johnson, Christopher B.; Lee, Haakil; Stoskopf, Michael K.; Macdonald, Jeffrey M.
The Eastern oyster (Crassostrea virginica) is a useful, robust model marine organism for tissue metabolism studies. Its relatively few organs are easily delineated and there is sufficient understanding of their functions based on classical assays to support interpretation of advanced spectroscopic approaches. Here we apply high-resolution proton nuclear magnetic resonance (1H NMR)-based metabolomic analysis to C. virginica to investigate the differences in the metabolic profile of different organ groups, and magnetic resonance imaging (MRI) to non-invasively identify the well separated organs. Metabolites were identified in perchloric acid extracts of three portions of the oyster containing: (1) adductor muscle, (2) stomach and digestive gland, and (3) mantle and gills. Osmolytes dominated the metabolome in all three organ blocks with decreasing concentration as follows: betaine > taurine > proline > glycine > ▀-alanine > hypotaurine. Mitochondrial metabolism appeared most pronounced in the adductor muscle with elevated levels of carnitine facilitating ▀-oxidation, and ATP, and phosphoarginine synthesis, while glycogen was elevated in the mantle/gills and stomach/digestive gland. A biochemical schematic is presented that relates metabolites to biochemical pathways correlated with physiological organ functions. This study identifies metabolites and corresponding 1H NMR peak assignments for future NMR-based metabolomic studies in oysters. PMID:21116407
Exploring helical folding of oligoureas during chain elongation by high-resolution magic-angle-spinning (HRMAS) NMR spectroscopy.
Violette, Aude; Lancelot, Nathalie; Poschalko, Alexander; Piotto, Martial; Briand, Jean-Paul; Raya, Jesus; Elbayed, Karim; Bianco, Alberto; Guichard, Gilles
The development of novel folding oligomers (foldamers) for biological and biomedical applications requires both precise structural information and appropriate methods to detect folding propensity. However, the synthesis and the systematic conformational investigation of large arrays of oligomers to determine the influence of factors, such as chain length, side chains, and surrounding environment, on secondary structure can be quite tedious. Herein, we show for 2.5-helical N,N'-linked oligoureas (gamma-peptide lineage) that the whole process of foldamer characterization can be accelerated by using high-resolution magic-angle-spinning (HRMAS) NMR spectroscopy. This was achieved by monitoring a simple descriptor of conformational homogeneity (e.g., chemical shift difference between diastereotopic main chain CH2 protons) at different stages of oligourea chain growth on a solid support. HRMAS NMR experiments were conducted on two sets of oligoureas, ranging from dimer to hexamer, immobilized on DEUSS, a perdeuterated poly(oxyethylene)-based solid support swollen in solvents of low to high polarity. One evident advantage of the method is that only minute amount of material is required. In addition, the resonance of the deuterated resin is almost negligeable. On-bead NOESY spectra of high quality and with resolution comparable to that of liquid samples were obtained for longer oligomers, thus allowing detailed structural characterization. PMID:18381712
Conformations of silica-bound (pentafluorophenyl)propyl groups determined by solid-state NMR spectroscopy and theoretical calculations.
Mao, Kanmi; Kobayashi, Takeshi; Wiench, Jerzy W; Chen, Hung-Ting; Tsai, Chih-Hsiang; Lin, Victor S-Y; Pruski, Marek
The conformations of (pentafluorophenyl)propyl groups (-CH(2)-CH(2)-CH(2)-C(6)F(5), abbreviated as PFP), covalently bound to the surface of mesoporous silica nanoparticles (MSNs), were determined by solid-state NMR spectroscopy and further refined by theoretical modeling. Two types of PFP groups were described, including molecules in the prone position with the perfluorinated aromatic rings located above the siloxane bridges (PFP-p) and the PFP groups denoted as upright (PFP-u), whose aromatic rings do not interact with the silica surface. Two-dimensional (2D) (13)C-(1)H, (13)C-(19)F and (19)F-(29)Si heteronuclear correlation (HETCOR) spectra were obtained with high sensitivity on natural abundance samples using fast magic angle spinning (MAS), indirect detection of low-gamma nuclei and signal enhancement by Carr-Purcell-Meiboom-Gill (CPMG) spin-echo sequence. 2D double-quantum (DQ) (19)F MAS NMR spectra and spin-echo measurements provided additional information about the structure and mobility of the pentafluorophenyl rings. Optimization of the PFP geometry, as well as calculations of the interaction energies and (19)F chemical shifts, proved very useful in refining the structural features of PFP-p and PFP-u functional groups on the silica surface. The prospects of using the PFP-functionalized surface to modify its properties (e.g., the interaction with solvents, especially water) and design new types of the heterogeneous catalytic system are discussed. PMID:20707348
Elucidation of Specific Binding Sites for Organofluorine Compounds in Peat Humic Acid using Reversed Heteronuclear Saturation Transfer Difference NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Longstaffe, J. G.; Simpson, M. J.; Maas, W.; Simpson, A. J.
In this presentation, a modified version of the NMR technique of Saturation Transfer Difference (STD) NMR is used to identify the distinct structural components of a peat humic acid mixture to which organic contaminants may bind. In our version of this experiment the direction of saturation transfer is reversed, from small molecules to macromolecules, and the transfer is between heteronuclei, from 19F nuclei on organofluorides to 1H nuclei on humic acid components, hence our term: reversed-Heteronuclear Saturation Transfer Difference (r-HSTD) spectroscopy. In the r-HSTD spectra of a humic acid mixture, only those components in contact with an organofluorine species will be observed, the identity of which can be inferred from the 1H chemical shift. This approach is used here to show that aromatic organofluoride compounds interact preferentially with lignin- derived material, whereas an aliphatic perfluorocarboxylic acid interacts nearly exclusively with protein-derived material. These findings have direct implications in the greater understanding of soil sorption phenomenon, as we present a powerful tool for the elucidation of the specific interactions through which organic pollutants bind to natural organic matter.
Two-dimensional NMR spectroscopy reveals cation-triggered backbone degradation in polysulfone-based anion exchange membranes.
Arges, Christopher G; Ramani, Vijay
Anion exchange membranes (AEMs) find widespread applications as an electrolyte and/or electrode binder in fuel cells, electrodialysis stacks, flow and metal-air batteries, and electrolyzers. AEMs exhibit poor stability in alkaline media; their degradation is induced by the hydroxide ion, a potent nucleophile. We have used 2D NMR techniques to investigate polymer backbone stability (as opposed to cation stability) of the AEM in alkaline media. We report the mechanism behind a peculiar, often-observed phenomenon, wherein a demonstrably stable polysulfone backbone degrades rapidly in alkaline solutions upon derivatization with alkaline stable fixed cation groups. Using COSY and heteronuclear multiple quantum correlation spectroscopy (2D NMR), we unequivocally demonstrate that the added cation group triggers degradation of the polymer backbone in alkaline via quaternary carbon hydrolysis and ether hydrolysis, leading to rapid failure. This finding challenges the existing perception that having a stable cation moiety is sufficient to yield a stable AEM and emphasizes the importance of the often ignored issue of backbone stability. PMID:23335629
The Interaction between tRNA(Lys) 3 and the primer activation signal deciphered by NMR spectroscopy.
Sleiman, Dona; Barraud, Pierre; Brachet, Franck; Tisne, Carine
The initiation of reverse transcription of the human immunodeficiency virus type 1 (HIV-1) requires the opening of the three-dimensional structure of the primer tRNA(Lys) 3 for its annealing to the viral RNA at the primer binding site (PBS). Despite the fact that the result of this rearrangement is thermodynamically more stable, there is a high-energy barrier that requires the chaperoning activity of the viral nucleocapsid protein. In addition to the nucleotide complementarity to the PBS, several regions of tRNA(Lys) 3 have been described as interacting with the viral genomic RNA. Among these sequences, a sequence of the viral genome called PAS for "primer activation signal" was proposed to interact with the T-arm of tRNA(Lys) 3, this interaction stimulating the initiation of reverse transcription. In this report, we investigate the formation of this additional interaction with NMR spectroscopy, using a simple system composed of the primer tRNA(Lys) 3, the 18 nucleotides of the PBS, the PAS (8 nucleotides) encompassed or not in a hairpin structure, and the nucleocapsid protein. Our NMR study provides molecular evidence of the existence of this interaction and highlights the role of the nucleocapsid protein in promoting this additional RNA-RNA annealing. This study presents the first direct observation at a single base-pair resolution of the PAS/anti-PAS association, which has been proposed to be involved in the chronological regulation of the reverse transcription. PMID:23762248
Combined Reversed Phase HPLC, Mass Spectrometry, and NMR Spectroscopy for a Fast Separation and Efficient Identification of Phosphatidylcholines
Willmann, Jan; Thiele, Herbert; Leibfritz, Dieter
In respect of the manifold involvement of lipids in biochemical processes, the analysis of intact and underivatised lipids of body fluids as well as cell and tissue extracts is still a challenging task, if detailed molecular information is required. Therefore, the advantage of combined use of high-pressure liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy will be shown analyzing three different types of extracts of the ubiquitous membrane component phosphatidylcholine. At first, different reversed phase modifications were tested on phosphatidylcholines (PC) with the same effective carbon number (ECN) for their applicability in lipid analysis. The results were taken to improve the separation of three natural PC extract types and a new reversed phase (RP)-HPLC method was developed. The individual species were characterized by one- and two-dimensional NMR and positive or negative ion mode quadrupole time of flight (q-TOF)-MS as well as MS/MS techniques. Furthermore, ion suppression effects during electrospray ionisation (ESI), difficulties, limits, and advantages of the individual analytical techniques are addressed. PMID:20871812
Investigating the water in hydrated sPEEK membranes using multiple quantum filtered 2H NMR spectroscopy.
Woudstra, Joel M; Ooms, Kristopher J
Double and zero quantum filtered (2)H NMR spectroscopy is used to study the structure and dynamics of D(2)O in sulfonated poly(ether ether ketone) membranes as a function of membrane hydration. Both residual quadrupolar coupling constants and T(2) relaxation values are obtained as a function of hydration. The residual couplings vary from 160 Hz at low hydration to 30 Hz at high hydration. The T(2) relaxation times range from 3 to 14 ms, with the high hydration values having longer T(2). Results from this study are compared to results obtained for Nafion membranes, revealing similarities and differences in the water environments of the two membranes that result from the structure of the polymers and can be related to properties such as water diffusion. PMID:23214923
Metabolomic profilings of urine and serum from high fat-fed rats via 1H NMR spectroscopy and pattern recognition.
Xu, Jingjing; Liu, Changqin; Cai, Shuhui; Dong, Jiyang; Li, Xuejun; Feng, Jianghua; Chen, Zhong
(1)H NMR spectroscopy in combination with multivariate statistical analysis was applied to explore the metabolic variability in urine and serum of high fat-fed rats relative to normal chow-fed ones. Metabolites contributing to intergroup discrimination identified by partial least squares discriminant analysis include 3-hydroxybutyrate, glutamate, glutamine, citrate, choline, hippurate, alanine, lactate, creatinine, taurine, acetate, etc. The aging effect along with long-term feeding was delineated with metabolic trajectory in principal component analysis score plot and age-related differences on metabolic profiling under different dietary intervention were recognised. The identified metabolites responsible for obesity were all imported into a web tool for network-based interpretation of compound lists to interpret their functional context, molecular mechanisms and disturbed signalling pathway globally and systematically. The results are useful for interpreting the pathology of obesity and further probing into the relationship between dietary-induced obesity and type 2 diabetes mellitus. PMID:23306893
Allostery and binding cooperativity of the catalytic subunit of protein kinase A by NMR spectroscopy and molecular dynamics simulations.
Masterson, Larry R; Cembran, Alessandro; Shi, Lei; Veglia, Gianluigi
The catalytic subunit of cAMP-dependent protein kinase A (PKA-C) is an exquisite example of a single molecule allosteric enzyme, where classical and modern views of allosteric signaling merge. In this chapter, we describe the mapping of PKA-C conformational dynamics and allosteric signaling in the free and bound states using a combination of NMR spectroscopy and molecular dynamics simulations. We show that ligand binding affects the enzyme's conformational dynamics, shaping the free-energy landscape toward the next stage of the catalytic cycle. While nucleotide and substrate binding enhance the enzyme's conformational entropy and define dynamically committed states, inhibitor binding attenuates the internal dynamics in favor of enthalpic interactions and delineates dynamically quenched states. These studies support a central role of conformational dynamics in many aspects of enzymatic turnover and suggest future avenues for controlling enzymatic function. PMID:22607761
The catalytic subunit of cAMP-dependent protein kinase A (PKA-C) is an exquisite example of a single molecule allosteric enzyme, where classical and modern views of allosteric signaling merge. In this chapter, we describe the mapping of PKA-C conformational dynamics and allosteric signaling in the free and bound states using a combination of NMR spectroscopy and molecular dynamics simulations. We show that ligand binding affects the enzymeÆs conformational dynamics, shaping the free-energy landscape toward the next stage of the catalytic cycle. While nucleotide and substrate binding enhance the enzymeÆs conformational entropy and define dynamically committed states, inhibitor binding attenuates the internal dynamics in favor of enthalpic interactions and delineates dynamically quenched states. These studies support a central role of conformational dynamics in many aspects of enzymatic turnover and suggest future avenues for controlling enzymatic function. PMID:22607761
A Timesaving Strategy for MAS NMR Spectroscopy by Combining Non-Uniform Sampling and Paramagnetic Relaxation Assisted Condensed Data Collection
Sun, Shangjin; Yan, Si; Guo, Changmiao; Li, Mingyue; Hoch, Jeffrey C.; Williams, John C.; Polenova, Tatyana
We present a timesaving strategy for acquiring 3D magic angle spinning NMR spectra for chemical shift assignments in proteins and protein assemblies in the solid state. By simultaneous application of non-uniform sampling (NUS) and paramagnetic-relaxation-assisted condensed data collection (PACC), we can attain 16-fold time reduction in the 3D experiments without sacrificing the signal-to-noise ratio or the resolution. We demonstrate that with appropriate concentration of paramagnetic dopant introduced into the sample the overwhelming majority of chemical shifts are not perturbed, with the exception of a limited number of shifts corresponding to residues located at the surface of the protein, which exhibit small perturbations. This approach enables multi-dimensional MAS spectroscopy in samples of intrinsically low sensitivity and/or high spectral congestion where traditional experiments fail, and is especially beneficial for structural and dynamics studies of large proteins and protein assemblies. PMID:23094591
Multiple-pulse and magic-angle spinning aided double-quantum proton solid-state NMR spectroscopy
NASA Astrophysics Data System (ADS)
Madhu, P. K.; Vinogradov, Elena; Vega, Shimon
We here report on a high-resolution pulse scheme for double-quantum (DQ) proton NMR spectroscopy in the solid-state. The pulse scheme employs a combination of multiple-pulses and magic-angle spinning (MAS) for both the excitation and conversion of DQ coherences and their evolution under homonuclear dipolar decoupling. This is made possible in this two-dimensional experiment by an effective combination of homonuclear dipolar decoupling method of phase modulated Lee-Goldburg and symmetry adapted sequence for homonuclear dipolar recoupling under MAS. DQ spectra of monoethyl fumaric acid, glycine, and histidine are presented to highlight the utility of the pulse scheme together with some of the existing drawbacks.
Assignments of 1H and 13C NMR spectral data for ondansetron and its two novel metabolites, 1-hydroxy-ondansetron diastereoisomers.
Duan, Mingyu; Huang, Haihua; Li, Xinnan; Chen, Xiaoyan; Zhong, Dafang
Assignments of 1H and 13C NMR chemical shifts were made by means of heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments for ondansetron, and by means of 1H-1H correlation spectroscopy (1H-1H COSY) and two-dimensional nuclear Overhauser effect spectroscopy (NOESY) experiments for two novel metabolites (M1 and M2) of ondansetron. These two metabolites were isolated for the first time from Mucor circinelloides. PMID:16835896
The interaction of ammonia and xenon with the imidazole glycerol phosphate synthase from Thermotoga maritima as detected by NMR spectroscopy
Liebold, Christoph; List, Felix; Kalbitzer, Hans Robert; Sterner, Reinhard; Brunner, Eike
The imidazole glycerol phosphate (ImGP) synthase from the hyperthermophilic bacterium Thermotoga maritima is a 1:1 complex of the glutaminase subunit HisH and the cyclase subunit HisF. It has been proposed that ammonia generated by HisH is transported through a channel to the active site of HisF, which generates intermediates of histidine (ImGP) and de novo biosynthesis of 5-aminoimidazole-4-carboxamideribotide. Solution NMR spectroscopy of ammonium chloride-titrated samples was used to study the interaction of NH3 with amino acids inside this channel. Although numerous residues showed 15N chemical shift changes, most of these changes were caused by nonspecific ionic strength effects. However, several interactions appeared to be specific. Remarkably, the amino acid residue Thr 78Śwhich is located in the central channelŚshows a large chemical shift change upon titration with ammonium chloride. This result and the reduced catalytic activity of the Thr78Met mutant indicate a special role of this residue in ammonia channeling. To detect and further characterize internal cavities in HisF, which might for example contribute to ammonia channeling, the interaction of HisF with the noble gas xenon was analyzed by solution NMR spectroscopy using 1H-15N HSQC experiments. The results indicate that HisF contains three distinct internal cavities, which could be identified by xenon-induced chemical shift changes of the neighboring amino acid residues. Two of these cavities are located at the active site at opposite ends of the substrate N?-[(5?-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide (PRFAR) binding groove. The third cavity is located in the interior of the central ?-barrel of HisF and overlaps with the putative ammonia transport channel. PMID:20665694
NMR/MS Translator for the Enhanced Simultaneous Analysis of Metabolomics Mixtures by NMR Spectroscopy and Mass Spectrometry: Application to Human Urine.
Bingol, Kerem; Br³schweiler, Rafael
A novel metabolite identification strategy is presented for the combined NMR/MS analysis of complex metabolite mixtures. The approach first identifies metabolite candidates from 1D or 2D NMR spectra by NMR database query, which is followed by the determination of the masses (m/z) of their possible ions, adducts, fragments, and characteristic isotope distributions. The expected m/z ratios are then compared with the MS(1) spectrum for the direct assignment of those signals of the mass spectrum that contain information about the same metabolites as the NMR spectra. In this way, the mass spectrum can be assigned with very high confidence, and it provides at the same time validation of the NMR-derived metabolites. The method was first demonstrated on a model mixture, and it was then applied to human urine collected from a pool of healthy individuals. A number of metabolites could be detected that had not been reported previously, further extending the list of known urine metabolites. The new analysis approach, which is termed NMR/MS Translator, is fully automated and takes only a few seconds on a computer workstation. NMR/MS Translator synergistically uses the power of NMR and MS, enhancing the accuracy and efficiency of the identification of those metabolites compiled in databases. PMID:25881480
Probing structure and dynamics of bulk and confined crude oils by multiscale NMR spectroscopy, diffusometry, and relaxometry.
Korb, Jean-Pierre; Louis-Joseph, Alain; Benamsili, LyĶs
We propose using a set of noninvasive multiscale NMR techniques for probing the structure and dynamics of bulk and confined crude oils with and without asphaltene. High-field 1D (1)H and (13)C NMR spectroscopies evidence the proton species and the amount of asphaltene and give an average chain length for the hydrocarbon aliphatic chains. Two-dimensional (1)H diffusion-ordered NMR spectroscopy (DOSY) spectra allow us to identify two populations of hydrocarbons characterized by two distributions of translational diffusion coefficients in the presence of asphaltene and a single one without asphaltene. A detailed analysis of the distributions of longitudinal, T1, relaxation times measured at different magnetic fields is proposed in terms of highly skewed bimodal (or monomodal) log-normal distributions, confirming the two environments in the presence of asphaltene and a single one without asphaltene. We show that these distributions are similar to the gas and gel permeation chromatography distributions, thus showing a connection of the hydrocarbon dynamics with their chain lengths. The remarkable observed features of the nuclear magnetic relaxation dispersion (NMRD) profiles of <1/T1> for bulk and confined crude oils with and without asphaltene are interpreted with an original relaxation model of intermittent surface dynamics of proton species at the proximity of asphaltene nanoaggregates and bulk dynamics in between clusters of these nanoaggregates. This allows us to probe the 2D translational diffusion correlation time and the time of residence of hydrocarbons in the proximity of the asphaltene nanoaggregates. Provided that the diffusion of the hydrocarbons close to the asphaltene nanoaggregates is three times smaller than the bulk diffusion, as the DOSY experiments show, this time of residence gives an average radius of exploration for the 2D hydrocarbon diffusion, r2D ? 3.9 nm, of the same order of magnitude as the aggregate sizes found by J. Eyssautier with SAXS and SANS in asphaltene solutions and by O. C. Mullins with the observation of gravitational gradients of asphaltenes in oilfield reservoirs. PMID:23687962
Intrauterine fetal brain NMR spectroscopy: 1H and 31P studies in rats
Nakada, T.; Kwee, I.L.; Suzuki, N.; Houkin, K. (Veterans Administration Medical Center, Martinez, CA (USA))
Fetal brain metabolism was investigated in utero noninvasively using multinuclear nuclear magnetic resonance spectroscopy in rats at two representative prenatal stages: early (17-18 days) and late (20-21 days) stages. Phosphorus-31 (31P) spectroscopy revealed that phosphocreatine is significantly lower in the early stage and increases to the level of early neonates by the late prenatal stage. Intracellular pH at the early stage was found to be strikingly high (7.52 +/- 0.21) and decreased to a level similar to that of neonates by the late stage (7.29 +/- 0.07). Phosphomonoester levels at both stages were similar to the values reported for early neonates. Water-suppressed proton (1H) spectroscopy demonstrated a distinctive in vivo fetal brain spectral pattern characterized by low levels of N-acetyl aspartate and high levels of taurine. High-resolution proton spectroscopy and homonuclear chemical-shift correlate spectroscopy of brain perchloric acid extracts confirmed these in vivo findings. In vitro 31P spectroscopy of acidified chloroform methanol extracts showed the characteristic membrane phospholipid profiles of fetal brain. The phosphatidylethanolamine (PE)-to-phosphatidylcholine (PC) ratio (PE/PC) did not show significant changes between the two stages at 0.40 +/- 0.11, a value similar to that of early neonates.
Effect of Ancillary Ligand on Electronic Structure as Probed by 51V Solid-State NMR Spectroscopy for Vanadium-o-Dioxolene Complexes
Goncharova-Zapata, Olga; Chatterjee, Pabitra B.; Hou, Guangjin; Quinn, Laurence L.; Li, Mingyue; Yehl, Jenna
A series of vanadium(V) complexes with o-dioxolene (catecholato) ligands and an ancillary ligand, (N-(salicylideneaminato)ethylenediamine) (hensal), were investigated using 51V solid-state magic angle spinning NMR spectroscopy (51V MAS NMR) to assess the local environment of the vanadium(V). The solid-state 51V NMR parameters of vanadium(V) complexes with a related potentially tetradentate ancillary ligand (N-salicylidene-N?-(2-hydroxyethyl)ethylenediamine) (h2shed) were previously shown to be associated with the size of the HOMO-LUMO gap in the complex, and as such provide insights on the interaction between metal ion and ligand (P. B. Chatterjee, et al., Inorg. Chem 50 (2011) 9794). Our results show that the modification of the ancillary ligand does not impact the observed trend between complexes ranging from catechols with electron rich to electron poor substituents. However, the ancillary ligand does impact the size of the HOMO-LUMO separation in the parent complex and thus the solid-state vanadium NMR chemical shift of the unsubstituted vanadium complex. For these complexes significant changes observed in the isotropic shifts and more modest changes detected in the CQ reflect the electronic changes in the complex as the catechol is varied. However, no obvious trend was observed in the chemical shift anisotropies (?? and ??) with the variation in the catechol. The electronic changes in the coordination environment of the vanadium can be described using solid-state 51V NMR spectroscopy. PMID:24353476
Characterizing RNA Dynamics at Atomic Resolution Using Solution-state NMR Spectroscopy
Bothe, Jameson R.; Nikolova, Evgenia N.; Eichhorn, Catherine D.; Chugh, Jeetender; Hansen, Alexandar L.; Al-Hashimi, Hashim M.
Many recently discovered non-coding RNAs do not fold into a single native conformation, but rather, sample many different conformations along their free energy landscape to carry out their biological function. Unprecedented insights into the RNA dynamic structure landscape are provided by solution-state NMR techniques that measure the structural, kinetic, and thermodynamic characteristics of motions spanning picosecond to second timescales at atomic resolution. From these studies a basic description of the RNA dynamic structure landscape is emerging, bringing new insights into how RNA structures change to carry out their function as well as applications in RNA-targeted drug discovery and RNA bioengineering. PMID:22036746
Determination of metabolite profiles in tropical wines by 1H NMR spectroscopy and chemometrics.
da Silva Neto, Humberto G; da Silva, JoŃo B P; Pereira, Giuliano E; Hallwass, Fernando
Traditionally, wines are produced in temperate climate zones, with one harvest per year. Tropical wines are a new concept of vitiviniculture that is being developed, principally in Brazil. The new Brazilian frontier is located in the northeast region (SŃo Francisco River Valley) in Pernambuco State, close to the equator, between 8 and 9 degrees S. Compared with other Brazilian and worldwide vineyards, the grapes of this region possess peculiar characteristics. The aim of this work is a preliminary study of commercial SŃo Francisco River Valley wines, analyzing their metabolite profiles by (1)H NMR and chemometric methods. PMID:19810052
Solvent effect in NMR spectroscopy: Methoxyl resonance shifts induced by trifluoroacetic acid in isoflavones
NASA Astrophysics Data System (ADS)
Jha, Hirday N.; Sanduja, Sudershan K.; Sanduja, Radhika; Parmar, Virinder S.
1H NMR spectra of eight different methoxylated isoflavones have been measured in deuterated chloroform and in a mixture (1 : 1) of deuterated chloroform and trifluoroacetic acid. The TFA-induced shifts of the methoxyl resonances have been interpreted and can serve as a guide in inferring the structures of natural or new isoflavones. This study is particularly useful in distinguishing a C-5 methoxyl from a C-7 methoxyl and a C-2' methoxyl from C-3' or C-4' methoxyl groups in an isoflavone. The steric, electronic and conformational factors are discussed to explain the different shift values.
Hadamard-encoded localized high-resolution NMR spectroscopy via intermolecular double-quantum coherences
NASA Astrophysics Data System (ADS)
Ke, Hanping; Cai, Honghao; Lin, Yanqin; Lin, Liangjie; Cai, Shuhui; Chen, Zhong
A scheme based on Hadamard encoding and intermolecular double-quantum coherences is designed to obtain localized one-dimensional high-resolution NMR spectra in inhomogeneous fields. Brief theoretical derivation was performed to illuminate its principle. Experiments were carried out on phantom solution and biological tissues to verify its effectiveness in yielding useful spectral information and efficiency in suppressing solvent signal even when the field inhomogeneity is sufficiently severe to erase almost all spectral information. This sequence may provide a promising way for analyzing heterogeneous biological tissues and chemical systems.
Ligand-detected relaxation dispersion NMR spectroscopy: dynamics of preQ1-RNA binding.
Moschen, Thomas; Wunderlich, Christoph Hermann; Spitzer, Romana; Levic, Jasmin; Micura, Ronald; Tollinger, Martin; Kreutz, Christoph
An NMR-based approach to characterizing the binding kinetics of ligand molecules to biomolecules, like RNA or proteins, by ligand-detected Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion experiments is described. A (15)N-modified preQ1 ligand is used to acquire relaxation dispersion experiments in the presence of low amounts of the Fsu class?I preQ1 aptamer RNA, and increasing ligand concentrations to probe the RNA small molecule interaction. Our experimental data strongly support the conformational selection mechanism postulated. The approach gives direct access to two parameters of a ligand-receptor interaction: the off rate and the population of the small molecule-receptor complex. A detailed description of the kinetics underlying the ligand binding process is of crucial importance to fully understanding a riboswitch's function and to evaluate potential new antibiotics candidates targeting the noncoding RNA species. Ligand-detected NMR relaxation dispersion experiments represent a valuable diagnostic tool for the characterization of binding mechanisms. PMID:25403518
Simulation studies of instrumental artifacts on spin I=1 double quantum filtered NMR spectroscopy
Sun, Cheng; Boutis, Gregory S.
We report on the results of a simulation based study of the effect of various experimental artifacts for spin I=1 double quantum filtered NMR. The simulation captures the effects of static field inhomogeneity, finite pulse widths, phase errors, transients and radio frequency inhomogeneity. We simulated the spectral distortions introduced under these errors for four, eight and sixteen step phase cycles that are well known in the NMR community. The dominating pulse errors are radio frequency field inhomogeneity and antisymmetric pulse transients. These errors result in the reduction of signal intensity as well as an introduction of distortions in the detected double quantum filtered spectrum. Using the simulation tool we studied the improvement one obtains when implementing a sixteen step phase cycle over a four step phase cycle. The results indicate that implementing a sixteen step phase cycle over an eight or four step phase cycle does not result in a significant reduction in the DQF intensity loss, or reduction in spectral distortions for antisymmetric transients. PMID:20451432
Intermediate Rate Atomic Trajectories of RNA by Solid State NMR Spectroscopy
Olsen, Greg L.; Bardaro, Michael F.; Echodu, Dorothy C.; Drobny, Gary P.; Varani, Gabriele
Many RNAs undergo large conformational changes in response to the binding of proteins and small molecules. However, when RNA functional dynamics occur in the ns-?s time scale they become invisible to traditional solution NMR relaxation methods. Residual dipolar couplings methods have revealed the presence of extensive ns-?s domain motions in HIV-1 TAR RNA, but this technique lacks information on the rates of motions. We have used solid-state deuterium NMR to quantitatively describe trajectories of key residues in TAR by exploiting the sensitivity of this technique to motions that occur in the ns-?s regime. Deuterium lineshape and relaxation data were used to model motions of residues within the TAR binding interface. The resulting motional models indicate that two functionally essential bases within the single stranded bulge sample both the free and Tat-bound conformations on the microsecond timescale in the complete absence of the protein. Thus, our results strongly support a conformational capture mechanism for recognition: the protein does not induce a new RNA structure, but instead captures an already-populated conformation. PMID:19994901
31P NMR spectroscopy of rat organs, in situ, using chronically implanted radiofrequency coils.
Koretsky, A P; Wang, S; Murphy-Boesch, J; Klein, M P; James, T L; Weiner, M W
A technique for making 31P NMR spectroscopic measurements in rat kidney, heart, and liver in vivo is presented. Two-turn solenoid coils were surgically implanted around the organ sufficiently in advance of NMR experiments to allow recovery of the animal. These chronically implanted coils allowed acquisition of high-resolution spectra at 40.5 and 97.3 MHz. No resolution improvement occurred at the higher field. Spectra were stable for up to 24 hr, during which time a variety of experiments could be performed. By accumulating spectra at 10-min intervals, the effects of intraperitoneal fructose injections were monitored; in kidney and liver, a rapid increase in sugar phosphates at the expense of Pi and ATP resulted. Fructose had no effect on heart metabolite levels. Spectra from the heart in vivo were obtained at systole and diastole by gating the spectrometer to the aortic pressure wave; no differences in phosphate metabolites were detected. Finally, saturation transfer techniques were used to monitor the rate of ATP synthesis in the kidney. The unidirectional rate constant for the conversion of Pi to ATP was 0.12 +/- 0.03 sec-1. Images PMID:6584867
Cryptophane-xenon complexes in organic solvents observed through NMR spectroscopy.
Huber, Gaspard; Beguin, Laetitia; Desvaux, Hervķ; Brotin, Thierry; Fogarty, Heather A; Dutasta, Jean-Pierre; Berthault, Patrick
The interaction of xenon with cryptophane derivatives is analyzed by NMR by using either thermal or hyperpolarized noble gas. Twelve hosts differing by their stereochemistry, cavity size, and the nature and the number of the substituents on the aromatic rings have been included in the study, in the aim of extracting some clues for the optimization of (129)Xe-NMR based biosensors derived from these cage molecules. Four important properties have been examined: xenon-host binding constant, in-out exchange rate of the noble gas, chemical shift, and relaxation of caged xenon. This work aims at understanding the main characteristics of the host-guest interaction in order to choose the best candidate for the biosensing approach. Moreover, rationalizing xenon chemical shift as a function of structural parameters would also help for setting up multiplexing applications. Xenon exhibits the highest affinity for the smallest cryptophane, namely cryptophane-111, and a long relaxation time inside it, convenient for conservation of its hyperpolarization. However, very slow in-out xenon exchange could represent a limitation for its future applicability for the biosensing approach, because the replenishment of the cage in laser-polarized xenon, enabling a further gain in sensitivity, cannot be fully exploited. PMID:18925727
Screening protein ¢ Single stranded RNA complexes by NMR spectroscopy for structure determination?
Foot, Jaelle N.; Feracci, Mikael; Dominguez, Cyril
In the past few years, RNA molecules have been revealed to be at the center of numerous biological processes. Long considered as passive molecules transferring genetic information from DNA to proteins, it is now well established that RNA molecules play important regulatory roles. Associated with that, the number of identified RNA binding proteins (RBPs) has increased considerably and mutations in RNA molecules or RBP have been shown to cause various diseases, such as cancers. It is therefore crucial to understand at the molecular level how these proteins specifically recognise their RNA targets in order to design new generation drug therapies targeting protein¢RNA complexes. Nuclear magnetic resonance (NMR) is a particularly well-suited technique to study such protein¢RNA complexes at the atomic level and can provide valuable information for new drug discovery programs. In this article, we describe the NMR strategy that we and other laboratories use for screening optimal conditions necessary for structural studies of protein-single stranded RNA complexes, using two proteins, Sam68 and T-STAR, as examples. PMID:24096002
Understanding membrane protein interaction and regulation using solid state NMR spectroscopy
Shyamasundar, R.K.
spectroscopy and their application in understanding regulation of cardiac and skeletal muscle relaxation and regulation molecular level in their native environment Ł I will discuss some of my work in the development regulation of cardiac and skeletal muscle relaxation processes. Specifically, the structural basis
Molecular degradation of ancient documents revealed by 1H HR-MAS NMR spectroscopy
NASA Astrophysics Data System (ADS)
Corsaro, Carmelo; Mallamace, Domenico; ?ojewska, Joanna; Mallamace, Francesco; Pietronero, Luciano; Missori, Mauro
For centuries mankind has stored its knowledge on paper, a remarkable biomaterial made of natural cellulose fibers. However, spontaneous cellulose degradation phenomena weaken and discolorate paper over time. The detailed knowledge of products arising from cellulose degradation is essential in understanding deterioration pathways and in improving durability of cultural heritage. In this study, for the first time, products of cellulose degradation were individually detected in solid paper samples by means of an extremely powerful proton HR-MAS NMR set-up, in combination to a wise use of both ancient and, as reference, artificially aged paper samples. Carboxylic acids, in addition to more complex dicarboxylic and hydroxy-carboxylic acids, were found in all samples studied. Since these products can catalyze further degradation, their knowledge is fundamental to improve conservation strategies of historical documents. Furthermore, the identification of compounds used in ancient production techniques, also suggests for artifacts dating, authentication and provenance.
Molecular degradation of ancient documents revealed by 1H HR-MAS NMR spectroscopy
Corsaro, Carmelo; Mallamace, Domenico; ?ojewska, Joanna; Mallamace, Francesco; Pietronero, Luciano; Missori, Mauro
For centuries mankind has stored its knowledge on paper, a remarkable biomaterial made of natural cellulose fibers. However, spontaneous cellulose degradation phenomena weaken and discolorate paper over time. The detailed knowledge of products arising from cellulose degradation is essential in understanding deterioration pathways and in improving durability of cultural heritage. In this study, for the first time, products of cellulose degradation were individually detected in solid paper samples by means of an extremely powerful proton HR-MAS NMR set-up, in combination to a wise use of both ancient and, as reference, artificially aged paper samples. Carboxylic acids, in addition to more complex dicarboxylic and hydroxy-carboxylic acids, were found in all samples studied. Since these products can catalyze further degradation, their knowledge is fundamental to improve conservation strategies of historical documents. Furthermore, the identification of compounds used in ancient production techniques, also suggests for artifacts dating, authentication and provenance. PMID:24104201
Validation of a lanthanide tag for the analysis of protein dynamics by paramagnetic NMR spectroscopy.
Hass, Mathias A S; Keizers, Peter H J; Blok, Anneloes; Hiruma, Yoshitaka; Ubbink, Marcellus
Paramagnetic lanthanide tags potentially can enhance the effects of microsecond to millisecond dynamics in proteins on NMR signals and provide structural information on lowly populated states encoded in the pseudocontact shifts. We have investigated the microsecond to millisecond mobility of a two-point attached lanthanide tag, CLaNP-5, using paramagnetic (1)H CPMG relaxation dispersion methods. CLaNP-5 loaded with Lu(3+), Yb(3+), or Tm(3+) was attached to three sites on the surface of two proteins, pseudoazurin and cytochrome c. The paramagnetic center causes large relaxation dispersion effects for two attachment sites, suggesting that local dynamics of the protein at the attachment site causes mobility of the paramagnetic center. At one site the relaxation dispersions are small and limited to the immediate environment of the tag. It is concluded that paramagnetic relaxation dispersion could represent a sensitive method to probe protein dynamics. However, the selection of a rigid attachment site is of critical importance. PMID:20586489
Non-micellar systems for solution NMR spectroscopy of membrane proteins
Raschle, Thomas; Hiller, Sebastian; Etzkorn, Manuel; Wagner, Gerhard
Integral membrane proteins play essential roles in many biological processes, such as energy transduction, transport of molecules, and signaling. The correct function of membrane proteins is likely to depend strongly on the chemical and physical properties of the membrane. However, membrane proteins are not accessible to many biophysical methods in their native cellular membrane. A major limitation for their functional and structural characterization is thus the requirement for an artificial environment that mimics the native membrane to preserve the integrity and stability of the membrane protein. Most commonly employed are detergent micelles, which can however be detrimental to membrane protein activity and stability. Here, we review recent developments for alternative, non-micellar solubilization techniques, with a particular focus on their application to solution NMR studies. We discuss the use of amphipols and lipid bilayer systems, such as bicelles and nanolipoprotein particles (NLPs). The latter show great promise for structural studies in near native membranes. PMID:20570504
De novo determination of peptide structure with solid-state magic-angle spinning NMR spectroscopy
NASA Astrophysics Data System (ADS)
Rienstra, Chad M.; Tucker-Kellogg, Lisa; Jaroniec, Christopher P.; Hohwy, Morten; Reif, Bernd; McMahon, Michael T.; Tidor, Bruce; Lozano-Pķrez, Tomßs; Griffin, Robert G.
The three-dimensional structure of the chemotactic peptide N-formyl-L-Met-L-Leu-L-Phe-OH was determined by using solid-state NMR (SSNMR). The set of SSNMR data consisted of 16 13C-15N distances and 18 torsion angle constraints (on 10 angles), recorded from uniformly 13C,15N- and 15N-labeled samples. The peptide's structure was calculated by means of simulated annealing and a newly developed protocol that ensures that all of conformational space, consistent with the structural constraints, is searched completely. The result is a high-quality structure of a molecule that has thus far not been amenable to single-crystal diffraction studies. The extensions of the SSNMR techniques and computational methods to larger systems appear promising.
High-resolution NMR spectroscopy of biological tissues usingprojected Magic Angle Spinning
Martin, Rachel W.; Jachmann, Rebecca C.; Sakellariou, Dimitris; Nielsen, Ulla Gro; Pines, Alexander
High-resolution NMR spectra of materials subject toanisotropic broadening are usually obtained by rotating the sample aboutthe magic angle, which is 54.7 degrees to the static magnetic field. Inprojected Magic Angle Spinning (p-MAS), the sample is spun about twoangles, neither of which is the magic angle. This provides a method ofobtaining isotropic spectra while spinning at shallow angles. The p-MASexperiment may be used in situations where spinning the sample at themagic angle is not possible due to geometric or other constraints,allowing the choice of spinning angle to be determined by factors such asthe shape of the sample, rather than by the spin physics. The applicationof this technique to bovine tissue samples is demonstrated as a proof ofprinciple for future biological or medical applications.
Quantitation of intermolecular dipolar effects in NMR spectroscopy and high order MSE MR imaging.
Chen, Z; Kennedy, S D; Zhong, J
An analytical expression for intermolecular dipolar effects was derived for the CRAZED sequence with an arbitrary flip angle of the second RF pulse and time-varying gradients. A combination of the demagnetizing field theory and product operator formalism was utilized in the derivation. It is demonstrated that the time-averaged, not instantaneous, orientation of the applied gradients determines the contributions of long-range intermolecular dipole effects. An imaging sequence to detect intermolecular dipolar effects was designed. The second- and third-order multiple spin echo (MSE) NMR signals of swine muscle were observed and were found to be in good agreement with the theoretical predictions. MSE images of a water phantom with nth orders (n = 2, - 3, - 4, and - 5) were also obtained, and their relative signal intensities and optimized TE values were elucidated and compared with the theoretical prediction. PMID:11154953
Essential Parameters for Structural Analysis and Dereplication by 1H NMR Spectroscopy
The present study demonstrates the importance of adequate precision when reporting the ? and J parameters of frequency domain 1H NMR (HNMR) data. Using a variety of structural classes (terpenoids, phenolics, alkaloids) from different taxa (plants, cyanobacteria), this study develops rationales that explain the importance of enhanced precision in NMR spectroscopic analysis and rationalizes the need for reporting ?? and ?J values at the 0.1¢1 ppb and 10 mHz level, respectively. Spectral simulations paired with iteration are shown to be essential tools for complete spectral interpretation, adequate precision, and unambiguous HNMR-driven dereplication and metabolomic analysis. The broader applicability of the recommendation relates to the physicochemical properties of hydrogen (1H) and its ubiquity in organic molecules, making HNMR spectra an integral component of structure elucidation and verification. Regardless of origin or molecular weight, the HNMR spectrum of a compound can be very complex and encode a wealth of structural information that is often obscured by limited spectral dispersion and the occurrence of higher order effects. This altogether limits spectral interpretation, confines decoding of the underlying spin parameters, and explains the major challenge associated with the translation of HNMR spectra into tabulated information. On the other hand, the reproducibility of the spectral data set of any (new) chemical entity is essential for its structure elucidation and subsequent dereplication. Handling and documenting HNMR data with adequate precision is critical for establishing unequivocal links between chemical structure, analytical data, metabolomes, and biological activity. Using the full potential of HNMR spectra will facilitate the general reproducibility for future studies of bioactive chemicals, especially of compounds obtained from the diversity of terrestrial and marine organisms. PMID:24895010
Investigation by NMR spectroscopy of the interaction between synthetic soluble (-)-dopa melanin and drugs.
Salazar-Bookaman, M M; Fowble, J; Weber, P; Patil, P N
In order to understand the molecular interactions of drugs with melanin, synthetic soluble (-)-dopa-melanin was prepared in deuterium buffer. The spectra of various drug moieties with the pigment at 30 degrees C were studied employing the line width measurements obtained with a pulse NMR (AF270) instrument. As compared to drug effects in fresh melanins (48 h), the aged melanins (greater than or equal to 168 h) gave consistent spectral measurements, even in dilute solutions of pigment. NMR signals of aromatic and N-methyl protons of drugs were relatively easy to quantify and, in the presence of melanin, line broadening of various drug moieties occurred. The line widths of the N-methyl groups of acetylcholine (3.02 ppm), the N-methyl group of atropine (2.52 ppm), N-isopropyl of isoprenaline bitartrate (1.14 ppm) and N-ter-butyl of timolol maleate (1.22 ppm) in the presence of the pigment were increased. Line widths associated with acetate, bitartrate, maleate or tropic acid, however, were not altered by the melanin. This indicates the specificity of the interaction between drug moieties and the site(s) of melanin. Based on the line width measurements of N-methyl protons of ephedrine, two dissociation constants were obtained (Kd1 2.08 mM and Kd2 greater than 20 mM). The constants for atropine melanin complex were Kd1 0.79 mM and Kd2 greater than 6 mM. Furthermore, based on N-methyl resonances, it appears that atropine and ephedrine compete for at least one common interacting site of the melanin polymer. PMID:2515443
High-resolution molecular structure of a peptide in an amyloid fibril determined by magic angle spinning NMR spectroscopy.
Jaroniec, Christopher P; MacPhee, Cait E; Bajaj, Vikram S; McMahon, Michael T; Dobson, Christopher M; Griffin, Robert G
Amyloid fibrils are self-assembled filamentous structures associated with protein deposition conditions including Alzheimer's disease and the transmissible spongiform encephalopathies. Despite the immense medical importance of amyloid fibrils, no atomic-resolution structures are available for these materials, because the intact fibrils are insoluble and do not form diffraction-quality 3D crystals. Here we report the high-resolution structure of a peptide fragment of the amyloidogenic protein transthyretin, TTR(105-115), in its fibrillar form, determined by magic angle spinning NMR spectroscopy. The structure resolves not only the backbone fold but also the precise conformation of the side chains. Nearly complete (13)C and (15)N resonance assignments for TTR(105-115) formed the basis for the extraction of a set of distance and dihedral angle restraints. A total of 76 self-consistent experimental measurements, including 41 restraints on 19 backbone dihedral angles and 35 (13)C-(15)N distances between 3 and 6 A were obtained from 2D and 3D NMR spectra recorded on three fibril samples uniformly (13)C, (15)N-labeled in consecutive stretches of four amino acids and used to calculate an ensemble of peptide structures. Our results indicate that TTR(105-115) adopts an extended beta-strand conformation in the amyloid fibrils such that both the main- and side-chain torsion angles are close to their optimal values. Moreover, the structure of this peptide in the fibrillar form has a degree of long-range order that is generally associated only with crystalline materials. These findings provide an explanation of the unusual stability and characteristic properties of this form of polypeptide assembly. PMID:14715898
Determination of neo- and d-chiro-Inositol Hexakisphosphate in Soils by Solution 31P NMR Spectroscopy
The inositol phosphates are an abundant but poorly understood group of organic phosphorus compounds found widely in the environment. Four stereoisomers of inositol hexakisphosphate (IP6) occur, although for three of these (scyllo, neo, and d-chiro) the origins, dynamics, and biological function remain unknown, due in large part to analytical limitations in their measurement in environmental samples. We synthesized authentic neo- and d-chiro-IP6 and used them to identify signals from these compounds in three soils from the Falkland Islands. Both compounds resisted hypobromite oxidation and gave quantifiable 31P NMR signals at ? = 6.67 ppm (equatorial phosphate groups of the 4-equatorial/2-axial conformer of neo-IP6) and ? = 6.48 ppm (equatorial phosphate groups of the 2-equatorial/4-axial conformer of d-chiro-IP6) in soil extracts. Inositol hexakisphosphate accounted for 46¢54% of the soil organic phosphorus, of which the four stereoisomers constituted, on average, 55.9% (myo), 32.8% (scyllo), 6.1% (neo), and 5.2% (d-chiro). Reappraisal of the literature based on the new signal assignments revealed that neo- and d-chiro-IP6 occur widely in both terrestrial and aquatic ecosystems. These results confirm that the inositol phosphates can constitute a considerable fraction of the organic phosphorus in soils and reveal the prevalence of neo- and d-chiro-IP6 in the environment. The hypobromite oxidation and solution 31P NMR spectroscopy procedure allows the simultaneous quantification of all four IP6 stereoisomers in environmental samples and provides a platform for research into the origins and ecological significance of these enigmatic compounds. PMID:22489788
Interactions between a humic acid and a paramagnetic cation as assessed by CPMAS 13C NMR spectroscopy
NASA Astrophysics Data System (ADS)
Conte, P.; van Lagen, B.
Humic substances (HSs) are natural organic materials playing a very important role in environment due to their ability in interacting with organic and inorganic compounds. From the one side, HSs can reduce the toxic effects of organic and inorganic contaminants, while, from the other side, they can enhance availability of nutrients, such as cations, to living organisms including plants. For this reason it is very crucial to understand the mechanisms of the interactions between humic substances and the environmentally relevant chemical components. In the present work, we have investigated the mechanisms of interaction between a HS and iron (III) by using cross polarization magic angle spinning (CPMAS) 13C NMR spectroscopy. For that, complexes between HS and different amounts of Fe(III) were prepared. All the HS-Fe(III) complexes were analysed by variable contact time (VCT) NMR experiments in order to obtain estimations of the values of the cross-polarization time (TCH) and the proton longitudinal relaxation time in the rotating frame (T1rho(H)). Results confirmed literature findings by which carboxyl groups are the most important humic fraction endowing with the ability to chelate Fe(III). However, our results also demonstrated that direct bondages between HS and Fe(III) involve the remaining polar systems such as carbohydrates and peptides. Conversely, alkyls and aromatics appeared not to be directly bound to the paramagnetic iron (III). We also evaluated the distances between Fe(III) and the different functional groups in the HS through the analysis of the proton spin diffusion into the HS-Fe(III) complexes.
Determination of neo- and D-chiro-inositol hexakisphosphate in soils by solution 31P NMR spectroscopy.
Turner, Benjamin L; Cheesman, Alexander W; Godage, H Yasmin; Riley, Andrew M; Potter, Barry V L
The inositol phosphates are an abundant but poorly understood group of organic phosphorus compounds found widely in the environment. Four stereoisomers of inositol hexakisphosphate (IP(6)) occur, although for three of these (scyllo, neo, and D-chiro) the origins, dynamics, and biological function remain unknown, due in large part to analytical limitations in their measurement in environmental samples. We synthesized authentic neo- and D-chiro-IP(6) and used them to identify signals from these compounds in three soils from the Falkland Islands. Both compounds resisted hypobromite oxidation and gave quantifiable (31)P NMR signals at ? = 6.67 ppm (equatorial phosphate groups of the 4-equatorial/2-axial conformer of neo-IP(6)) and ? = 6.48 ppm (equatorial phosphate groups of the 2-equatorial/4-axial conformer of D-chiro-IP(6)) in soil extracts. Inositol hexakisphosphate accounted for 46-54% of the soil organic phosphorus, of which the four stereoisomers constituted, on average, 55.9% (myo), 32.8% (scyllo), 6.1% (neo), and 5.2% (D-chiro). Reappraisal of the literature based on the new signal assignments revealed that neo- and D-chiro-IP(6) occur widely in both terrestrial and aquatic ecosystems. These results confirm that the inositol phosphates can constitute a considerable fraction of the organic phosphorus in soils and reveal the prevalence of neo- and D-chiro-IP(6) in the environment. The hypobromite oxidation and solution (31)P NMR spectroscopy procedure allows the simultaneous quantification of all four IP(6) stereoisomers in environmental samples and provides a platform for research into the origins and ecological significance of these enigmatic compounds. PMID:22489788
High-resolution molecular structure of a peptide in an amyloid fibril determined by magic angle spinning NMR spectroscopy
NASA Astrophysics Data System (ADS)
Jaroniec, Christopher P.; Macphee, Cait E.; Bajaj, Vikram S.; McMahon, Michael T.; Dobson, Christopher M.; Griffin, Robert G.
Amyloid fibrils are self-assembled filamentous structures associated with protein deposition conditions including Alzheimer's disease and the transmissible spongiform encephalopathies. Despite the immense medical importance of amyloid fibrils, no atomic-resolution structures are available for these materials, because the intact fibrils are insoluble and do not form diffraction-quality 3D crystals. Here we report the high-resolution structure of a peptide fragment of the amyloidogenic protein transthyretin, TTR(105-115), in its fibrillar form, determined by magic angle spinning NMR spectroscopy. The structure resolves not only the backbone fold but also the precise conformation of the side chains. Nearly complete 13C and 15N resonance assignments for TTR(105-115) formed the basis for the extraction of a set of distance and dihedral angle restraints. A total of 76 self-consistent experimental measurements, including 41 restraints on 19 backbone dihedral angles and 35 13C-15N distances between 3 and 6 ┼ were obtained from 2D and 3D NMR spectra recorded on three fibril samples uniformly 13C, 15N-labeled in consecutive stretches of four amino acids and used to calculate an ensemble of peptide structures. Our results indicate that TTR(105-115) adopts an extended -strand conformation in the amyloid fibrils such that both the main- and side-chain torsion angles are close to their optimal values. Moreover, the structure of this peptide in the fibrillar form has a degree of long-range order that is generally associated only with crystalline materials. These findings provide an explanation of the unusual stability and characteristic properties of this form of polypeptide assembly.
Effect of Oxygen Concentration on Viability and Metabolism in a Fluidized-Bed Bioartificial Liver Using 31P and 13C NMR Spectroscopy
Jeffries, Rex E.; Gamcsik, Michael P.; Keshari, Kayvan R.; Pediaditakis, Peter; Tikunov, Andrey P.; Young, Gregory B.; Lee, Haakil; Watkins, Paul B.
Many oxygen mass-transfer modeling studies have been performed for various bioartificial liver (BAL) encapsulation types; yet, to our knowledge, there is no experimental study that directly and noninvasively measures viability and metabolism as a function of time and oxygen concentration. We report the effect of oxygen concentration on viability and metabolism in a fluidized-bed NMR-compatible BAL using in vivo 31P and 13C NMR spectroscopy, respectively, by monitoring nucleotide triphosphate (NTP) and 13C-labeled nutrient metabolites, respectively. Fluidized-bed bioreactors eliminate the potential channeling that occurs with packed-bed bioreactors and serve as an ideal experimental model for homogeneous oxygen distribution. Hepatocytes were electrostatically encapsulated in alginate (avg. diameter, 500??m; 3.5ū107 cells/mL) and perfused at 3?mL/min in a 9-cm (inner diameter) cylindrical glass NMR tube. Four oxygen treatments were tested and validated by an in-line oxygen electrode: (1) 95:5 oxygen:carbon dioxide (carbogen), (2) 75:20:5 nitrogen:oxygen:carbon dioxide, (3) 60:35:5 nitrogen:oxygen:carbon dioxide, and (4) 45:50:5 nitrogen:oxygen:carbon dioxide. With 20% oxygen, ?-NTP steadily decreased until it was no longer detected at 11?h. The 35%, 50%, and 95% oxygen treatments resulted in steady ?-NTP levels throughout the 28-h experimental period. For the 50% and 95% oxygen treatment, a 13C NMR time course (?5?h) revealed 2-13C-glycine and 2-13C-glucose to be incorporated into [2-13C-glycyl]glutathione (GSH) and 2-13C-lactate, respectively, with 95% having a lower rate of lactate formation. 31P and 13C NMR spectroscopy is a noninvasive method for determining viability and metabolic rates. Modifying tissue-engineered devices to be NMR compatible is a relatively easy and inexpensive process depending on the bioreactor shape. PMID:22835003
High-Resolution 1H NMR Spectroscopy of Fish Muscle, Eggs and Small Whole Fish via Hadamard-Encoded Intermolecular Multiple-Quantum Coherence
Cai, Honghao; Chen, Yushan; Cui, Xiaohong; Cai, Shuhui; Chen, Zhong
Background and Purpose Nuclear magnetic resonance (NMR) spectroscopy has become an important technique for tissue studies. Since tissues are in semisolid-state, their high-resolution (HR) spectra cannot be obtained by conventional NMR spectroscopy. Because of this restriction, extraction and high-resolution magic angle spinning (HR MAS) are widely applied for HR NMR spectra of tissues. However, both of the methods are subject to limitations. In this study, the feasibility of HR 1H NMR spectroscopy based on intermolecular multiple-quantum coherence (iMQC) technique is explored using fish muscle, fish eggs, and a whole fish as examples. Materials and Methods Intact salmon muscle tissues, intact eggs from shishamo smelt and a whole fish (Siamese algae eater) are studied by using conventional 1D one-pulse sequence, Hadamard-encoded iMQC sequence, and HR MAS. Results When we use the conventional 1D one-pulse sequence, hardly any useful spectral information can be obtained due to the severe field inhomogeneity. By contrast, HR NMR spectra can be obtained in a short period of time by using the Hadamard-encoded iMQC method without shimming. Most signals from fatty acids and small metabolites can be observed. Compared to HR MAS, the iMQC method is non-invasive, but the resolution and the sensitivity of resulting spectra are not as high as those of HR MAS spectra. Conclusion Due to the immunity to field inhomogeneity, the iMQC technique can be a proper supplement to HR MAS, and it provides an alternative for the investigation in cases with field distortions and with samples unsuitable for spinning. The acquisition time of the proposed method is greatly reduced by introduction of the Hadamard-encoded technique, in comparison with that of conventional iMQC method. PMID:24466083
Recoupling of chemical shift anisotropy by R-symmetry sequences in magic angle spinning NMR spectroscopy
Hou, Guangjin; Byeon, In-Ja L.; Ahn, Jinwoo; Gronenborn, Angela M.; Polenova, Tatyana
13C and 15N chemical shift (CS) interaction is a sensitive probe of structure and dynamics in a wide variety of biological and inorganic systems, and in the recent years several magic angle spinning NMR approaches have emerged for residue-specific measurements of chemical shift anisotropy (CSA) tensors in uniformly and sparsely enriched proteins. All of the currently existing methods are applicable to slow and moderate magic angle spinning (MAS) regime, i.e., MAS frequencies below 20 kHz. With the advent of fast and ultrafast MAS probes capable of spinning frequencies of 40¢100ĀkHz, and with the superior resolution and sensitivity attained at such high frequencies, development of CSA recoupling techniques working under such conditions is necessary. In this work, we present a family of R-symmetry based pulse sequences for recoupling of 13C/15N CSA interactions that work well in both natural abundance and isotopically enriched systems. We demonstrate that efficient recoupling of either first-rank (?1) or second-rank (?2) spatial components of CSA interaction is attained with appropriately chosen ?-encoded RNnv symmetry sequences. The advantage of these ?-encoded RNnv-symmetry based CSA (RNCSA) recoupling schemes is that they are suitable for CSA recoupling under a wide range of MAS frequencies, including fast MAS regime. Comprehensive analysis of the recoupling properties of these RNnv symmetry sequences reveals that the ?1-CSA recoupling symmetry sequences exhibit large scaling factors; however, the partial homonuclear dipolar Hamiltonian components are symmetry allowed, which makes this family of sequences suitable for CSA measurements in systems with weak homonuclear dipolar interactions. On the other hand, the ?-encoded symmetry sequences for ?2-CSA recoupling have smaller scaling factors but they efficiently suppress the homonuclear dipole-dipole interactions. Therefore, the latter family of sequences is applicable for measurements of CSA parameters in systems with strong homonuclear dipolar couplings, such as uniformly-13C labeled biological solids. We demonstrate RNCSA NMR experiments and numerical simulations establishing the utility of this approach to the measurements of 13C and 15N CSA parameters in model compounds, [15N]-N-acetyl-valine (NAV), [U-13C, 15N]-alanine, [U-13C,15N]-histidine, and present the application of this approach to [U-13C/15N]-Tyr labeled C-terminal domain of HIV-1 CA protein. PMID:23039592
Recoupling of chemical shift anisotropy by R-symmetry sequences in magic angle spinning NMR spectroscopy
NASA Astrophysics Data System (ADS)
Hou, Guangjin; Byeon, In-Ja L.; Ahn, Jinwoo; Gronenborn, Angela M.; Polenova, Tatyana
13C and 15N chemical shift (CS) interaction is a sensitive probe of structure and dynamics in a wide variety of biological and inorganic systems, and in the recent years several magic angle spinning NMR approaches have emerged for residue-specific measurements of chemical shift anisotropy (CSA) tensors in uniformly and sparsely enriched proteins. All of the currently existing methods are applicable to slow and moderate magic angle spinning (MAS) regime, i.e., MAS frequencies below 20 kHz. With the advent of fast and ultrafast MAS probes capable of spinning frequencies of 40-100 kHz, and with the superior resolution and sensitivity attained at such high frequencies, development of CSA recoupling techniques working under such conditions is necessary. In this work, we present a family of R-symmetry based pulse sequences for recoupling of 13C/15N CSA interactions that work well in both natural abundance and isotopically enriched systems. We demonstrate that efficient recoupling of either first-rank (?1) or second-rank (?2) spatial components of CSA interaction is attained with appropriately chosen ?-encoded RNnv symmetry sequences. The advantage of these ?-encoded RNnv-symmetry based CSA (RNCSA) recoupling schemes is that they are suitable for CSA recoupling under a wide range of MAS frequencies, including fast MAS regime. Comprehensive analysis of the recoupling properties of these RNnv symmetry sequences reveals that the ?1-CSA recoupling symmetry sequences exhibit large scaling factors; however, the partial homonuclear dipolar Hamiltonian components are symmetry allowed, which makes this family of sequences suitable for CSA measurements in systems with weak homonuclear dipolar interactions. On the other hand, the ?-encoded symmetry sequences for ?2-CSA recoupling have smaller scaling factors but they efficiently suppress the homonuclear dipole-dipole interactions. Therefore, the latter family of sequences is applicable for measurements of CSA parameters in systems with strong homonuclear dipolar couplings, such as uniformly-13C labeled biological solids. We demonstrate RNCSA NMR experiments and numerical simulations establishing the utility of this approach to the measurements of 13C and 15N CSA parameters in model compounds, [15N]-N-acetyl-valine (NAV), [U-13C, 15N]-alanine, [U-13C,15N]-histidine, and present the application of this approach to [U-13C/15N]-Tyr labeled C-terminal domain of HIV-1 CA protein.
High field NMR spectroscopy and FTICR mass spectrometry: powerful discovery tools for the molecular level characterization of marine dissolved organic matter from the South Atlantic Ocean
NASA Astrophysics Data System (ADS)
Hertkorn, N.; Harir, M.; Koch, B. P.; Michalke, B.; Grill, P.; Schmitt-Kopplin, P.
Non target high resolution organic structural spectroscopy of marine dissolved organic matter (DOM) isolated on 27 November 2008 by means of solid phase extraction (SPE) from four different depths in the South Atlantic Ocean off the Angola coast (3.1░ E; -17.7░ S; Angola basin) provided molecular level information of complex unknowns with unprecedented coverage and resolution. The sampling was intended to represent major characteristic oceanic regimes of general significance: 5 m (FISH; near surface photic zone), 48 m (FMAX; fluorescence maximum), 200 m (upper mesopelagic zone) and 5446 m (30 m above ground). 800 MHz proton (1H) nuclear magnetic resonance (NMR) 1H NMR, spectra were least affected by fast and differential transverse NMR relaxation and produced at first similar looking, rather smooth bulk NMR envelopes reflecting intrinsic averaging from massive signal overlap. Visibly resolved NMR signatures were most abundant in surface DOM but contributed at most a few percent to the total 1H NMR integral and were mainly limited to unsaturated and singly oxygenated carbon chemical environments. The relative abundance and variance of resolved signatures between samples was maximal in the aromatic region; in particular, the aromatic resolved NMR signature of the deep ocean sample at 5446 m was considerably different from that of all other samples. When scaled to equal total NMR integral, 1H NMR spectra of the four marine DOM samples revealed considerable variance in abundance for all major chemical environments across the entire range of chemical shift. Abundance of singly oxygenated CH units and acetate derivatives declined from surface to depth whereas aliphatics and carboxyl-rich alicyclic molecules (CRAM) derived molecules increased in abundance. Surface DOM contained a remarkably lesser abundance of methyl esters than all other marine DOM, likely a consequence of photodegradation from direct exposure to sunlight. All DOM showed similar overall 13C NMR resonance envelopes typical of an intricate mixture of natural organic matter with noticeable peaks of anomerics and C-aromatics carbon whereas oxygenated aromatics and ketones were of too low abundance to result in noticeable humps at the S/N ratio provided. Integration according to major substructure regimes revealed continual increase of carboxylic acids and ketones from surface to deep marine DOM, reflecting a progressive oxygenation of marine DOM, with concomitant decline of carbohydrate-related substructures. Isolation of marine DOM by means of SPE likely discriminated against carbohydrates but produced materials with beneficial NMR relaxation properties: a substantial fraction of dissolved organic molecules present allowed the acquisition of two-dimensional NMR spectra with exceptional resolution. JRES, COSY and HMBC NMR spectra were capable to depict resolved molecular signatures of compounds exceeding a certain minimum abundance. Here, JRES spectra suffered from limited resolution whereas HMBC spectra were constrained because of limited S/N ratio. Hence, COSY NMR spectra appeared best suited to depict organic complexity in marine DOM. The intensity and number of COSY cross peaks was found maximal for sample FMAX and conformed to about 1500 molecules recognizable in variable abundance. Surface DOM (FISH) produced a slightly (~25%) lesser number of cross peaks with remarkable positional accordance to FMAX (~80% conforming COSY cross peaks were found in FISH and FMAX). With increasing water depth, progressive attenuation of COSY cross peaks was caused by fast transverse NMR relaxation of yet unknown origin. However, most of the faint COSY cross peak positions of deep water DOM conformed to those observed in the surface DOM, suggesting the presence of a numerous set of identical molecules throughout the entire ocean column even if the investigated water masses belonged to different oceanic regimes and currents. Aliphatic chemical environments of methylene (CH2) and methyl (CH3) in marine DOM were nicely discriminated in DEPT HSQC NMR spectra. Classical methyl gro
Unique Backbone-Water Interaction Detected in Sphingomyelin Bilayers with 1H/31P and 1H/13C HETCOR MAS NMR Spectroscopy
Holland, Gregory P.; Alam, Todd M.
Two-dimensional 1H/31P dipolar heteronuclear correlation (HETCOR) magic-angle spinning nuclear magnetic resonance (NMR) is used to investigate the correlation of the lipid headgroup with various intra- and intermolecular proton environments. Cross-polarization NMR techniques involving 31P have not been previously pursued to a great extent in lipid bilayers due to the long 1H-31P distances and high degree of headgroup mobility that averages the dipolar coupling in the liquid crystalline phase. The results presented herein show that this approach is very promising and yields information not readily available with other experimental methods. Of particular interest is the detection of a unique lipid backbone-water intermolecular interaction in egg sphingomyelin (SM) that is not observed in lipids with glycerol backbones like phosphatidylcholines. This backbone-water interaction in SM is probed when a mixing period allowing magnetization exchange between different 1H environments via the nuclear Overhauser effect (NOE) is included in the NMR pulse sequence. The molecular information provided by these 1H/31P dipolar HETCOR experiments with NOE mixing differ from those previously obtained by conventional NOE spectroscopy and heteronuclear NOE spectroscopy NMR experiments. In addition, two-dimensional 1H/13C INEPT HETCOR experiments with NOE mixing support the 1H/31P dipolar HETCOR results and confirm the presence of a H2O environment that has nonvanishing dipolar interactions with the SM backbone. PMID:18390621
Metabolomics study of Saw palmetto extracts based on 1H NMR spectroscopy.
de Combarieu, Eric; Martinelli, Ernesto Marco; Pace, Roberto; Sardone, Nicola
Preparations containing Saw palmetto extracts are used in traditional medicine to treat benign prostatic hyperplasia. According to the European and the American Pharmacopoeias, the extract is obtained from comminuted Saw palmetto berries by a suitable extracting procedure using ethanol or supercritical carbon dioxide or a mixture of n-hexane and methylpentanes. In the present study an approach to metabolomics profiling using nuclear magnetic resonance (NMR) has been used as a finger-printing tool to assess the overall composition of the extracts. The phytochemical analysis coupled with principal component analysis (PCA) showed the same composition of the Saw palmetto extracts obtained with carbon dioxide and hexane with minor not significant differences for extracts obtained with ethanol. In fact these differences are anyhow lower than the batch-to-batch variability ascribable to the natural-occurring variability in the Saw palmetto fruits' phytochemical composition. The fingerprinting analysis combined with chemometric method, is a technique, which would provide a tool to comprehensively assess the quality control of Saw palmetto extracts. PMID:25707588
Biosynthesis of aromatic compounds: 13C NMR spectroscopy of whole Escherichia coli cells.
Ogino, T; Garner, C; Markley, J L; Herrmann, K M
13C and 31P NMR spectra of wild-type Escherichia coli showed resonances from metabolic intermediates of glycolysis and ATP formation but no detectable signals from aromatic amino acids. However, tyrosine biosynthesis from D-[l-13C]glucose was observed in cells harboring a feedback-resistant allele of aroF, the gene encoding tyrosine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase [7-phospho-2-keto-3-deoxy-D-arabino-heptonate D-erythrose-4-phosphate-lyase (pyruvate-phosphorylating), EC184.108.40.206], one of the isoenzymes that control carbon flow through the common aromatic biosynthetic pathway. A similar accumulation of tyrosine and phenylalanine is seen in cells carrying a multiple-copy plasmid that carries a wild-type aroF allele in addition to pheA and tyrA, the structural genes for controlling enzymes of the terminal pathways to phenylalanine and tyrosine biosynthesis. These in vivo measurements by a noninvasive probe suggest feedback inhibition as the quantitatively major mechanism controlling carbon flow in the common aromatic compound biosynthetic pathway. In strains accumulating aromatic amino acids, a transient accumulation of trehalose was detected, indicating that previously unknown changes in Escherichia coli metabolism accompany overproduction of aromatic compounds. PMID:6136965
Conformational Dynamics of Escherichia coli Flavodoxins in Apo- and Holo-States by Solution NMR Spectroscopy
Jin, Changwen
Flavodoxins are a family of small FMN-binding proteins that commonly exist in prokaryotes. They utilize a non-covalently bound FMN molecule to act as the redox center during the electron transfer processes in various important biological pathways. Although extensive investigations were performed, detailed molecular mechanisms of cofactor binding and electron transfer remain elusive. Herein we report the solution NMR studies on Escherichia coli flavodoxins FldA and YqcA, belonging to the long-chain and short-chain flavodoxin subfamilies respectively. Our structural studies demonstrate that both proteins show the typical flavodoxin fold, with extensive conformational exchanges observed near the FMN binding pocket in their apo-forms. Cofactor binding significantly stabilizes both proteins as revealed by the extension of secondary structures in the holo-forms, and the overall rigidity shown by the backbone dynamics data. However, the 50 s loops of both proteins in the holo-form still show conformational exchanges on the Ąs-ms timescales, which appears to be a common feature in the flavodoxin family, and might play an important role in structural fine-tuning during the electron transfer reactions. PMID:25093851
Study of the hydrophobic cavity of beta-cryptogein through laser-polarized xenon NMR spectroscopy.
Berthault, Patrick; Huber, Gaspard; Ha, Phuong Thu; Dubois, Lionel; Desvaux, Hervķ; Guittet, Eric
The interaction of xenon with beta-cryptogein, a basic 10 kDa protein belonging to the elicitin family, has been studied by using dissolved thermal and laser-polarized gas in liquid-state NMR. 13C and 1H chemical-shift-mapping experiments were unfruitful, the proton lines only experienced a slight narrowing but no significant frequency variation when the xenon concentration was increased. Nevertheless magnetization transfer from hyperpolarized xenon to protons of the protein demonstrates an undoubted interaction and enables localization of the noble-gas-binding site. Due to the proton-proton cross-relaxation efficiency, however, this experiment is subjected to important spin-diffusion. An automatic procedure that takes spin-diffusion into account when assigning the protons that interact with xenon is then used. The binding site, as defined by 30 Xe--H interactions, is situated in the inner core of the protein. The protons that interact with xenon border the channel by which sterols are known to enter into the cavity. These results support the idea that xenon is a good probe for hydrophobic protein regions. PMID:16292784
Chemical curing in alkyd paints: an evaluation via FT-IR and NMR spectroscopies.
Bartolozzi, G; Marchiafava, V; Mirabello, V; Peruzzini, M; Picollo, M
A study aimed at determining the time necessary for an alkyd paint to attain chemical curing is presented. In particular, the object of our investigation was an oil paint made by Winsor & Newton, namely French ultramarine (PB29) in the Griffin Alkyd "fast drying oil colour" series. Using this paint, we prepared several mock-ups on glass. These were left in the laboratory at room temperature in a piece of furniture with glass doors for a total of 70 days. Samples were taken at different times, and the changes in their composition were monitored by means of FT-IR and multinuclear NMR spectroscopic analyses. Since the cross-linking reactions involved in the formation of the pictorial film mainly affect the amount of carbon-carbon double bonds, we monitored the decrease in allyl, diallyl and vinyl protons and carbons. The data obtained from the use of both techniques led us to conclude that, in our particular experimental conditions, the chemical curing of the paint layer is reached within the first 70 days, thus establishing the beginning of the ageing phenomena. PMID:24084480
Molybdenum modified phosphate glasses studied by 31P MAS NMR and Raman spectroscopy
NASA Astrophysics Data System (ADS)
Szumera, Magdalena
Glasses have been synthesized in the system P2O5sbnd SiO2sbnd K2Osbnd MgOsbnd CaO modified by addition of MoO3. Glasses were prepared by conventional fusion method from 40 g batches. The influence of Mo-cations on the analysed glass structure was investigated by means of Raman and 31P MAS-NMR techniques. It has been found that molybdate units can form Mo[MoO4/MoO6]sbnd Osbnd P and/or Mo[MoO4/MoO6]sbnd Osbnd Si bonds with non-bridging oxygens atoms of Q2 methaphosphate units, resulting in the transformation of chain methaphosphate structure into pyrophosphate and finally into orthophosphate structure. It has been also found that increasing amount of MoO3 in the structure of investigated glasses causes their gradual depolymerization and molybdenum ions in the analysed glass matrix act as modifying cations.
Small-molecule binding sites on proteins established by paramagnetic NMR spectroscopy.
Guan, Jia-Ying; Keizers, Peter H J; Liu, Wei-Min; L÷hr, Frank; Skinner, Simon P; Heeneman, Edwin A; Schwalbe, Harald; Ubbink, Marcellus; Siegal, Gregg
Determining the three-dimensional structure of a small molecule-protein complex with weak affinity can be a significant challenge. We present a paramagnetic NMR method to determine intermolecular structure restraints based on pseudocontact shifts (PCSs). Since the ligand must be in fast exchange between free and bound states and the fraction bound can be as low as a few percent, the method is ideal for ligands with high micromolar to millimolar dissociation constants. Paramagnetic tags are attached, one at a time, in a well-defined way via two arms at several sites on the protein surface. The ligand PCSs were measured from simple 1D (1)H spectra and used as docking restraints. An independent confirmation of the complex structure was carried out using intermolecular NOEs. The results show that structures derived from these two approaches are similar. The best results are obtained if the magnetic susceptibility tensors of the tags are known, but it is demonstrated that with two-armed probes, the magnetic susceptibility tensor can be predicted with sufficient accuracy to provide a low-resolution model of the ligand orientation and the location of the binding site in the absence of isotope-labeled protein. This approach can facilitate fragment-based drug discovery in obtaining structural information on the initial fragment hits. PMID:23509882
Structural characterization of Ru-bleomycin complexes by resonance Raman, circular dichroism, and NMR spectroscopy.
Mouzopoulou, B; Kozlowski, H; Katsaros, N; Garnier-Suillerot, A
A series of spectroscopic techniques including absorption and CD spectra, resonance Raman spectra, and (1)H NMR as well as electrospray mass spectrometry have shown that Ru(II) ion binds to bleomycin, forming an equimolar complex, similarly to Fe(II), i.e., via the secondary amine nitrogen, the pyrimidine ring nitrogen, the deprotonated peptide bond nitrogen of the histydyl residue, and the histidine imidazole nitrogen, which are bound in the equatorial positions, and the alpha-amino nitrogen of beta-aminoalanine, which coordinates in the apical position above pH 7. The reaction of Ru(II)-BLM with O(2), H(2)O(2),or PhIO leads to formation of the oxy species in which only one oxygen atom is bound to metal ion. According to our data, the reaction of Ru(II)-BLM complex with oxygen species leads to different product than that suggested for Fe(II)-BLM. The formation of the BLM-Ru-O-Ru-BLM dimeric unit, similar to that found for sterically unhindered Ru porphyrins, seems to be the most likely. PMID:11754273
Detection and characterization of acidic compartments (vacuoles) in Chlorella vulgaris 11h cells by 31 Pin vivo NMR spectroscopy and cytochemical techniques
K. Kuchitsu; T. Oh-hama; M. Tsuzuki; S. Miyachi
Acidic inorganic phosphate (Pi) pool (pH around 6) was detected besides the cytoplasmic pool in intact cells of Chlorella vulgaris 11h by 31P-in vivo nuclear magnetic resonance (NMR) spectroscopy. It was characterized as acidic compartments (vacuoles) in combination with the cytochemical technique; staining the cells with neutral red and chloroquine which are known as basic reagents specifically accumulated in acidic
Structure and dynamics of dimyristoylphosphatidic acid\\/calcium complexes by sup 2 H NMR, infrared, and Raman spectroscopies and small-angle X-ray diffraction
Gaetan Laroche; M. Pezolet; E. J. Dufourc; J. Dufourcq
The structural and dynamic properties of complexes of dimyristoylphosphatidic acid (DMPA) and calcium ions have been characterized by ┬▓H NMR, Raman, and infrared spectroscopies and small-angle X-ray diffraction. All techniques used show that these complexes do not undergo a cooperative thermotropic phase transition. Small-angle X-ray diffraction unambiguously demonstrates that the structure of the lipid molecules of the DMPA\\/Ca{sup 2+} complexes
Strength by joining methods: combining synthesis with NMR, IR, and vibrational circular dichroism spectroscopy for the determination of the relative configuration in hemicalide.
De Gussem, Ewoud; Herrebout, Wouter; Specklin, Simon; Meyer, Christophe; Cossy, Janine; Bultinck, Patrick
The relative configuration of a key subunit of hemicalide, a recently isolated, highly bioactive marine natural product having potent antiproliferative activity against a panel of human cancer cell lines, was assigned by combining stereocontrolled synthesis of model substrates with NMR, IR, and vibrational circular dichroism (VCD) spectroscopy. The assignment of the absolute configuration of asymmetric carbon center C42 in two structurally complex epimeric substructures containing six stereocenters by VCD analysis illustrates the power and reliability of combining methods. PMID:25346258
Local Ca-Mg distribution of Mg-rich pyrope-grossular garnets synthesized at different temperatures revealed by 29Si MAS NMR spectroscopy
Pyrope-grossular solid solutions, (Mg,Ca) 3Al2Si3O12, of composition Py85Gr15 and Py75Gr25 were synthesized at 1000, 1200, and 1400 ░C and 30 kbars in a piston-cylinder device. The synthetic garnets were characterized using optical, microprobe, and X-ray methods and their Ca-Mg distribu- tions were investigated using 29 Si MAS NMR spectroscopy. The syntheses produced 100% garnet except for those undertaken at 1000
Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy
Petersen, Line B.; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro
Ordering of gallium(III) in a series of magnesium gallium layered double hydroxides (LDHÆs), [Mg1-xGax(OH)2(NO3)x yH2O], was determined using solid-state 1H and 71Ga NMR spectroscopy. Depletion of Ga in these LDHÆs is demonstrated to be the result of soluble [Ga(OH)4]-complexes formed during synthesis.
Orientational ordering of a banana-shaped solute molecule in a nematic calamitic solvent by {sup 2}H-NMR spectroscopy: An indication of glasslike behavior
Cinacchi, Giorgio; Domenici, Valentina [Dipartimento di Chimica, Universita di Pisa, Via Risorgimento 35, I-56126, Pisa (Italy)
The Saupe ordering matrix of a banana-shaped mesogenic molecule as a solute in a common nematic calamitic solvent has been determined by {sup 2}H-NMR spectroscopy as a function of temperature. The temperature dependence of the Saupe ordering matrix element associated with the principal molecular axis is consistent with a glassy behavior in the reorientational motion of this particular solute molecule. The Haller expression, appropriately modified, provides a good fit to the experimental data.
Mechanistic investigations of the methanol-to-olefin (MTO) process on acidic zeolite catalysts by in situ solid-state NMR spectroscopy
Wei Wang; Yijiao Jiang; Michael Hunger
This paper reviews mechanistic investigations of the methanol-to-olefin (MTO) process by in situ solid-state NMR spectroscopy, mainly performed under continuous-flow and stopped-flow conditions. During methanol conversion on the silicoaluminophosphate H-SAPO-34 under continuous-flow conditions, a hydrocarbon-pool consisting of a mixture of C6¢C12 olefins and aromatics was found. The hydrocarbon-pool mechanism was verified as the dominating route in the MTO process under
Decreased TCA cycle rate in the rat brain after acute 3NP treatment measured by in vivo 1H-{13C} NMR spectroscopy
Pierre-Gilles Henry; Vincent Lebon; Francoise Vaufrey; Emmanuel Brouillet; Philippe Hantrayeand; Gilles Bloch
Inhibition of succinate dehydrogenase (SDH) by the mitoch- ondrial toxin 3-nitropropionic acid (3-NP) has gained accept- ance as an animal model of Huntington's disease. In this study 13 C NMR spectroscopy was used to measure the tricarboxylic acid (TCA) cycle rate in the rat brain after 3-NP treatment. The time course of both glutamate C4 and C3 13C labelling was
Identification and quantitation of 3,4-methylenedioxy- N-methylamphetamine (MDMA, ecstasy) in human urine by 1H NMR spectroscopy. Application to five cases of intoxication
Jonathan Liu; John Decatur; Gloria Proni; Elise Champeil
Identification of 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) in five cases of intoxication using nuclear magnetic resonance (NMR) spectroscopy of human urine is reported. A new water suppression technique PURGE (Presaturation Utilizing Relaxation Gradients and Echoes) was used. A calibration curve was obtained using spiked samples. The method gave a linear response (correlation coefficient of 0.992) over the range 0.01¢1mg\\/mL. Subsequently, quantitation of
In vivo localized 1H NMR spectroscopy at 11.7 Tesla
NASA Astrophysics Data System (ADS)
Crozier, Stuart; Field, James; Brereton, Ian M.; Moxon, Leith N.; Shannon, Gerald F.; Doddrell, David M.
The SPACE volume-selection technique has been used to acquire high-resolution 1H spectra from the brain of neonate mice at 11.7 T (500 MHz). Spectra were acquired from voxels smaller than 20 ?l. The spectra display elevated intensities of resonances arising from taurine and reduced intensities of those arising from N-acetylaspartate, when compared to those of mature animals, correlating well with in vitro studies. An integrated probe design consisting of separate transmission and reception RF coils and linear gradient coils is described. Comments are made concerning the advantages and disadvantages of performing gradient-encoded localized spectroscopy at this field strength.
Quantitative analysis of iobitridol in an injectable preparation by 1H NMR spectroscopy.
Borioni, Anna; Gostoli, Gianluca; Boss∙, Elena; Sestili, Isabella
Nuclear magnetic resonance spectroscopy was used for direct quantitative determination of iobitridol in an injectable formulation. The method was developed on a medium field strength magnet (400MHz) and validation was performed by assessing specificity, accuracy, precision, linearity, stability of samples and robustness. Validation data confirm that the method is highly appropriate for direct quantification of iobitridol in the final formulation. Moreover the method has a good potential for rapid screening analyses due to straightforward experimental setup and lack of any sample pretreatment. PMID:24531005
Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy
Jawla, Sudheer; Ni, Qing Zhe; Barnes, Alexander; Guss, William; Daviso, Eugenio; Herzfeld, Judith; Griffin, Robert; Temkin, Richard
In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a 13C-Urea sample using this gyrotron. PMID:23539422
Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy.
Jawla, Sudheer; Ni, Qing Zhe; Barnes, Alexander; Guss, William; Daviso, Eugenio; Herzfeld, Judith; Griffin, Robert; Temkin, Richard
In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a (13)C-Urea sample using this gyrotron. PMID:23539422
The energetic cost of domain reorientation in maltose-binding protein as studied by NMR and fluorescence spectroscopy.
Millet, Oscar; Hudson, Rhea P; Kay, Lewis E
Maltose-binding protein (MBP) is a two-domain protein that undergoes a ligand-mediated conformational rearrangement from an "open" to a "closed" structure on binding to maltooligosaccharides. To characterize the energy landscape associated with this transition, we have generated five variants of MBP with mutations located in the hinge region of the molecule. Residual dipolar couplings, measured in the presence of a weak alignment medium, have been used to establish that the average structures of the mutant proteins are related to each other by domain rotation about an invariant axis, with the rotation angle varying from 5 degrees to 28 degrees. Additionally, the domain orientations observed in the wild-type apo and ligand-bound (maltose, maltotriose, etc.) structures are related through a rotation of 35 degrees about the same axis. Remarkably, the free energy of unfolding, measured by equilibrium denaturation experiments and monitored by fluorescence spectroscopy, shows a linear correlation with the rotation angle, with the stability of the (apo)protein decreasing with domain closure by 212 +/- 16 cal mol-1 per degree of rotation. The apparent binding energy for maltose also shows a similar correlation with the interdomain angle, suggesting that the mutations, as they relate to binding, affect predominantly the ligand-free structure. The linearity of the energy change is interpreted in terms of an increase in the extent of hydrophobic surface that becomes solvent accessible on closure. The combination of structural, stability, and binding data allows separation of the energetics of domain reorientation from ligand binding. This work presents a near quantitative structure-energy-binding relationship for a series of mutants of MBP, illustrating the power of combined studies involving protein engineering and solution NMR spectroscopy. PMID:14530390
Solid state NMR spectroscopy in the evaluation of the conformational changes of humic substances as affected by thermal variations
NASA Astrophysics Data System (ADS)
de Pasquale, C.; Berns, A. E.; Kucerik, J.; Conte, P.; Alonzo, G.
Soil organic matter (SOM) is an ubiquitous, complex material which is produced by the degradation of plant tissues and animal bodies. It is the major indicator of soil quality since it is directly involved in the maintenance of soil fertility, prevention of erosion and desert encroachment and provision of suitable environment for biological activity. Organic matter is an important driving force in environmental global change as it acts as both a source and sink of atmospheric carbon. However, SOM is subjected to rapid changes due to environmental transformations such as massive deforestations, fires, intensive land uses, temperature increases and so on. In the present work, a characterization of humic substances was done in order to obtain information about the transformation occurring to SOM as affected by temperature increases. For the first time variable temperature cross polarization magic angle spinning (CPMAS) 13C NMR spectroscopy was applied in combination with thermal analyses (TG and DSC) on environmentally relevant soil organic matter. The results show that the conformational changes occurring in humic substances as temperature is raised can be associated to melting of alkyl components connected with sublimation of some organic compounds. The simultaneous application of solid phase micro extraction GC-MS also allowed the identification of the components which were released by sublimation processes.
Recombinant proteins incorporating short non-native extensions may display increased aggregation propensity as detected by high resolution NMR spectroscopy.
Zanzoni, Serena; D'Onofrio, Mariapina; Molinari, Henriette; Assfalg, Michael
The use of a recombinant protein to investigate the function of the native molecule requires that the former be obtained with the same amino acid sequence as the template. However, in many cases few additional residues are artificially introduced for cloning or purification purposes, possibly resulting in altered physico-chemical properties that may escape routine characterization. For example, increased aggregation propensity without visible protein precipitation is hardly detected by most analytical techniques but its investigation may be of great importance for optimizing the yield of recombinant protein production in biotechnological and structural biology applications. In this work we show that bile acid binding proteins incorporating the common C-terminal LeuValProArg extension display different hydrodynamic properties from those of the corresponding molecules without such additional amino acids. The proteins were produced enriched in nitrogen-15 for analysis via heteronuclear NMR spectroscopy. Residue-specific spin relaxation rates were measured and related to rotational tumbling time and molecular size. While the native-like recombinant proteins show spin-relaxation rates in agreement with those expected for monomeric globular proteins of their mass, our data indicate the presence of larger adducts for samples of proteins with very short amino acid extensions. The used approach is proposed as a further screening method for the quality assessment of biotechnological protein products. PMID:23036197
Biochemical characterization of blood plasma of coronary artery disease patients by in vitro high-resolution proton NMR spectroscopy.
Malik, Anu; Sharma, Uma; Lakshmy, R; Narang, Rajiv; Jagannathan, Naranamanglam R
This study aimed to investigate the biochemical profile of blood plasma of patients with coronary artery disease (CAD) and angiographically normal subjects (controls) to determine biomarkers for their differentiation. In this double blind study, 5 mL venous blood was drawn before angiography from CAD patients (n=60) and controls (n=13) comprising angiography normal individuals. In vitro high-resolution NMR spectroscopy of these blood plasma samples was carried out at 400 MHz, and intensity data were analysed with partial least square discriminant analysis. Categorization of subjects as controls or CAD patients and the patients further as single vessel disease (SVD), double vessel disease (DVD) and triple vessel disease (TVD) was done at the end of the study based on their angiography reports. Raised levels of lipids, alanine (Ala) and isoleucine/leucine/valine (Ile/Leu/Val) were observed in CAD patients compared with controls. Partial least square discriminant analysis showed separation between controls vs CAD patients. TVD patients showed increased levels of Ile/Leu/Val and Ala compared with controls and SVD. Alanine, Ile/Leu/Val, and LDL/VLDL appear as possible biomarkers for distinguishing between controls and patients with SVD and TVD. A metabolic adaptation of myocardium may play a role in raising the Ala level. PMID:25740139
Detection of Butter Adulteration with Lard by Employing (1)H-NMR Spectroscopy and Multivariate Data Analysis.
Fadzillah, Nurrulhidayah Ahmad; Che Man, Yaakob Bin; Rohman, Abdul; Rosman, Arieff Salleh; Ismail, Amin; Mustafa, Shuhaimi; Khatib, Alfi
The authentication of food products from the presence of non-allowed components for certain religion like lard is very important. In this study, we used proton Nuclear Magnetic Resonance ((1)H-NMR) spectroscopy for the analysis of butter adulterated with lard by simultaneously quantification of all proton bearing compounds, and consequently all relevant sample classes. Since the spectra obtained were too complex to be analyzed visually by the naked eyes, the classification of spectra was carried out.The multivariate calibration of partial least square (PLS) regression was used for modelling the relationship between actual value of lard and predicted value. The model yielded a highest regression coefficient (R(2)) of 0.998 and the lowest root mean square error calibration (RMSEC) of 0.0091% and root mean square error prediction (RMSEP) of 0.0090, respectively. Cross validation testing evaluates the predictive power of the model. PLS model was shown as good models as the intercept of R(2)Y and Q(2)Y were 0.0853 and -0.309, respectively. PMID:25994556
Gender-Specific Metabolomic Profiling of Obesity in Leptin-Deficient ob/ob Mice by 1H NMR Spectroscopy
Kim, Sang-Woo; Jung, Youngae; Bae, Hyun-Whee; Lee, Daeyoup; Park, Sung Goo; Lee, Chul-Ho; Hwang, Geum-Sook; Chi, Seung-Wook
Despite the numerous metabolic studies on obesity, gender bias in obesity has rarely been investigated. Here, we report the metabolomic analysis of obesity by using leptin-deficient ob/ob mice based on the gender. Metabolomic analyses of urine and serum from ob/ob mice compared with those from C57BL/6J lean mice, based on the 1H NMR spectroscopy in combination with multivariate statistical analysis, revealed clear metabolic differences between obese and lean mice. We also identified 48 urine and 22 serum metabolites that were statistically significantly altered in obese mice compared to lean controls. These metabolites are involved in amino acid metabolism (leucine, alanine, ariginine, lysine, and methionine), tricarbocylic acid cycle and glucose metabolism (pyruvate, citrate, glycolate, acetoacetate, and acetone), lipid metabolism (cholesterol and carnitine), creatine metabolism (creatine and creatinine), and gut-microbiome-derived metabolism (choline, TMAO, hippurate, p-cresol, isobutyrate, 2-hydroxyisobutyrate, methylamine, and trigonelline). Notably, our metabolomic studies showed distinct gender variations. The obese male mice metabolism was specifically associated with insulin signaling, whereas the obese female mice metabolism was associated with lipid metabolism. Taken together, our study identifies the biomarker signature for obesity in ob/ob mice and provides biochemical insights into the metabolic alteration in obesity based on gender. PMID:24098417
Detection of phloridzin in strawberries (Fragaria x ananassa Duch.) by HPLC-PDA-MS/MS and NMR spectroscopy.
Hilt, Petra; Schieber, Andreas; Yildirim, Caner; Arnold, Gabi; Klaiber, Iris; Conrad, J³rgen; Beifuss, Uwe; Carle, Reinhold
The phenolic profile of strawberry fruits (Fragaria x ananassa Duch., Rosaceae) was investigated by high-performance liquid chromatography with photodiode array detection. A peak displaying retention time and UV spectral data identical to those of phloridzin (phloretin 2'-O-beta-d-glucoside), a dihydrochalcone glucoside so far considered characteristic of apples, was monitored. For further characterization, crude extracts of strawberries were purified on polyamide, and the target compound was isolated by preparative and analytical HPLC. Structure elucidation was performed on the basis of APCI- and ESI-MS in the negative ion mode as well as by 1D and 2D NMR spectroscopy using authentic phloridzin for comparison. The d-configuration of the sugar moiety was established by HPLC analysis of the corresponding acyclic 1-deoxy-1-(N-acetyl-alpha-methylbenzylamino)alditol acetate. Apart from its chemotaxonomic relevance, this first report on the occurrence of phloridzin in strawberries is of particular interest for the authenticity control of strawberry products such as juices, jams, and fruit preparations since phloridzin has so far been used for the detection of fraudulent admixtures. PMID:12720368
Following the Reaction of Heteroanions inside a {W18 O56 } Polyoxometalate Nanocage by NMR Spectroscopy and Mass Spectrometry.
Zheng, Qi; VilÓ-Nadal, Laia; Busche, Christoph; Mathieson, Jennifer S; Long, De-Liang; Cronin, Leroy
By incorporating phosphorus(III)-based anions into a polyoxometalate cage, a new type of tungsten-based unconventional Dawson-like cluster, [W18 O56 (HP(III) O3 )2 (H2 O)2 ](8-) , was isolated, in which the reaction of the two phosphite anions [HPO3 ](2-) within the {W18 O56 } cage could be followed spectroscopically. As well as full X-ray crystallographic analysis, we studied the reactivity of the cluster using both solution-state NMR spectroscopy and mass spectrometry. These techniques show that the cluster undergoes a structural rearrangement in solution whereby the {HPO3 } moieties dimerize to form a weakly interacting (O3 PH???HPO3 ) moiety. In the crystalline state the cluster exhibits a thermally triggered oxidation of the two P(III) template moieties to form P(V) ?centers (phosphite to phosphate), commensurate with the transformation of the cage into a Wells-Dawson {W18 O54 } cluster. PMID:26013548
Probing Membrane Topology of the Antimicrobial Peptide Distinctin by Solid-State NMR Spectroscopy in Zwitterionic and Charged Lipid Bilayers
Verardi, Raffaello; Traaseth, Nathaniel J.; Shi, Lei; Porcelli, Fernando; Monfregola, Luca; De Luca, Stefania; Amodeo, Pietro; Veglia, Gianluigi; Scaloni, Andrea
Distinctin is a 47-residue antimicrobial peptide, which interacts with negatively charged membranes and is active against Gram-positive and Gram-negative bacteria. Its primary sequence comprises two linear chains of 22 (chain 1) and 25 (chain 2) residues, linked by a disulfide bridge between Cys19 of chain 1 and Cys23 of chain 2. Unlike other antimicrobial peptides, distinctin in the absence of the lipid membrane has a well-defined three-dimensional structure, which protects it from protease degradation. Here, we used static solid-state NMR spectroscopy to study the topology of distinctin in lipid bilayers. We found that In mechanically aligned lipid bilayers (charged or zwitterionic) this heterodimeric peptide adopts an ordered conformation absorbed on the surface of the membrane, with the long helix (chain 2), approximately parallel to the lipid bilayer (?5░ from the membrane plane) and the short helix (chain 1) forming a ?24░ angle. Since at lipid-to-protein molar ratio of 50:1 the peptide does not disrupt the macroscopic alignment of either charged or zwitterionic lipid bilayers, it is possible that higher concentrations might be needed for the hypothesized pore formation, or alternatively, distinctin elicits its cell disruption action by other mechanisms. PMID:20719234
Conformational change study of dengue virus NS2B-NS3 protease using (19)F NMR spectroscopy.
Zhu, Lei; Yang, Jing; Li, Hua; Sun, Hongbin; Liu, Jinsong; Wang, Junfeng
The dengue virus NS2B-NS3 protease (NS2B-NS3p), an important antiviral target for drug development, has been reported to adopt an open or closed conformation in crystal structures with different NS2B C-terminus (NS2Bc) positioning. In solution, nevertheless, NS2B-NS3p forms a mixture of open, closed and maybe other intermediate conformations, which is difficult to characterize using conventional biophysical and biochemical techniques. In this study, we developed a new strategy to analyze these conformational changes using (19)F NMR spectroscopy. Low pH or bovine pancreatic trypsin inhibitor (BPTI) binding promote the conformation change from open to closed, showing the importance of charge forces in the interaction between NS2Bc and NS3p. The mutation H51A impairs the charge interaction and the pH dependence of the conformational changes. It stabilizes the open conformation, while the addition of BPTI still converts NS2B-NS3p from open to closed conformation. PMID:25918021
Structural characterization of the divalent cation sites of bacterial phosphotriesterase by 113Cd NMR spectroscopy.
Omburo, G A; Mullins, L S; Raushel, F M
The phosphotriesterase from Pseudomonas diminuta catalyzes the hydrolysis of organophosphate esters. The isolated native protein contains zinc, and removal of this metal abolishes the enzymatic activity. Reconstitution of the apoenzyme requires 2 mol of cadmium per mol of protein for full catalytic activity. The kcat and Km values for the hydrolysis of paraoxon for the cadmium-substituted enzyme are 4300 s-1 and 390 microM, respectively. These values compare favorably with the kinetic constants observed for the zinc-substituted enzyme (2300 s-1 and 78 microM). A hybrid enzyme containing one zinc and one cadmium ion is catalytically active, and the kinetic constants are nearly identical to the values obtained with the all-zinc-containing enzyme. The NMR spectrum of protein reconstituted with two 113Cd2+ ions per enzyme molecule exhibits cadmium resonances at 212 and 116 ppm downfield from Cd(ClO4)2. The two metal ions are, therefore, in significantly different chemical environments. These two binding sites have been designated the M alpha and M beta sites for the low- and high-field signals, respectively. Protein substituted with a single cadmium ion also shows two cadmium resonances, and thus one site is not completely filled prior to the binding of metal to the other site. The Cd/Zn hybrid protein shows a single cadmium resonance at 115 ppm, and thus the cadmium is occupying the M beta site while zinc is occupying the M alpha site. The positions of the observed chemical shifts for the two cadmium signals indicate that the ligands to both metals are composed of a mixture of oxygen and nitrogen atoms.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8396425
Methodological aspects of analysing human breast cancer cell lines by NMR spectroscopy.
McCormack, S A; Bearden, D; Dennison, D K; Egan, T; Misra, L; Hazlewood, C F
In an attempt to identify the factors which might affect the measurement of water proton relaxation times in cultured cells, we have begun a long-term study of two human breast cancer cell lines, MDA-MB-231 and MDA-MB-435s. We tested growth rates and cell cycle distribution as intrinsic properties of the cells as well as methodological steps which might affect the measurement of T1 and T2. A detailed examination of the growth rates of the two cell lines, easily recognized as slow (231) and fast (435s) in culture, revealed that this attribute is difficult to correlate precisely with T1s or T2s. The reason is that the relaxation times are necessarily measured at one point in time while the growth rates are a summation of ongoing processes occurring over hours. Cell cycle distribution, on the other hand, can be measured simultaneously with the relaxation times by using cells quick-frozen from the same suspension. By this method, cell cycle distribution appears to be reflected through an effect on T1s. For example, cell pellets distributed 72:15:14 in G0G1:S:G2M has longer T1s (p less than 0.01) than those distributed 43:34:23 in G0G1:S:G2M. Regarding methodological factors, trypsin appeared to lower water content and T2s in the 231 cell line. Drift in the cell cycle distribution after sample preparation did not become significant until after 2 hours in the NMR tube. It was important to standardize the force and duration of centrifugation of the cell pellets to minimize the contribution of the suspending medium without affecting cell viability. We conclude that, given careful control of methodological factors, differences in T1 may reflect metabolic differences as demonstrated by T1 differences in cell pellets showing divergent cell cycle distribution. PMID:6531402
Rapid screening for structural integrity of expressed proteins by heteronuclear NMR spectroscopy.
Gronenborn, A. M.; Clore, G. M.
A simple and rapid method based on 15N labeling and 1H-15N heteronuclear single quantum coherence spectroscopy is presented to directly assess the structural integrity of overexpressed proteins in crude Escherichia coli extracts without the need for any purification. The method is demonstrated using two different expression systems and two different proteins, the B1 immunoglobulin-binding domain of streptococcal protein G (56 residues) and human interleukin-1 beta (153 residues). It is shown that high quality 1H-15N correlation spectra, recorded in as little as 15 min and displaying only cross-peaks arising from the overexpressed protein of interest, can be obtained from crude E. coli extracts. PMID:8771212
Method And Apparatus For High Resolution Ex-Situ Nmr Spectroscopy
Pines, Alexander (Berkeley, CA); Meriles, Carlos A. (El Cerrito, CA); Heise, Henrike (Goettingen, DE); Sakellariou, Dimitrios (Oakland, CA); Moule, Adam (Berkeley, CA)
A method and apparatus for ex-situ nuclear magnetic resonance spectroscopy for use on samples outside the physical limits of the magnets in inhomogeneous static and radio-frequency fields. Chemical shift spectra can be resolved with the method using sequences of correlated, composite z-rotation pulses in the presence of spatially matched static and radio frequency field gradients producing nutation echoes. The amplitude of the echoes is modulated by the chemical shift interaction and an inhomogeneity free FID may be recovered by stroboscopically sampling the maxima of the echoes. In an alternative embodiment, full-passage adiabatic pulses are consecutively applied. One embodiment of the apparatus generates a static magnetic field that has a variable saddle point.
Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C-NMR spectroscopy (SIE-DOSY 13C-NMR)
Technology Transfer Automated Retrieval System (TEKTRAN)
Stable Isotope-Enhanced Diffusion Ordered (SIE-DOSY) 13C-NMR has been applied to 13C-enriched carbohydrates and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, a disaccharide and a trisaccharide. These 2D spectra were obtained with as little as 8 min of acq...
Solution conformations of proline rings in proteins studied by NMR spectroscopy.
Cai, M; Huang, Y; Liu, J; Krishnamoorthi, R
Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine beta-, gamma- and delta-hydrogens have been made on the basis of 1H-1H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs alpha-beta 3, beta 3-gamma 3, beta 2-gamma 2, gamma 2-delta 2, and gamma 3-delta 3 (2.3 A) are shorter than those in the pairs alpha-beta 2, beta 2-gamma 3, beta 3-gamma 2, gamma 2-delta 3, and gamma 3-delta 2 (2.7-3.0 A), resulting in stronger NOESY cross peaks. For the Up conformation, the beta 3-gamma 2 and gamma 2-delta 3 spin-spin coupling constants are small (< 3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5-12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the alpha-beta 2, beta 2-gamma 3, and gamma 3-delta 2 vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5-12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined. PMID:8589600
Assessing hepatic metabolic changes during progressive colonization of germ-free mouse by 1H NMR spectroscopy.
Heath, Peter; Claus, Sandrine Paule
It is well known that gut bacteria contribute significantly to the host homeostasis, providing a range of benefits such as immune protection and vitamin synthesis. They also supply the host with a considerable amount of nutrients, making this ecosystem an essential metabolic organ. In the context of increasing evidence of the link between the gut flora and the metabolic syndrome, understanding the metabolic interaction between the host and its gut microbiota is becoming an important challenge of modern biology. Colonization (also referred to as normalization process) designates the establishment of micro-organisms in a former germ-free animal. While it is a natural process occurring at birth, it is also used in adult germ-free animals to control the gut floral ecosystem and further determine its impact on the host metabolism. A common procedure to control the colonization process is to use the gavage method with a single or a mixture of micro-organisms. This method results in a very quick colonization and presents the disadvantage of being extremely stressful. It is therefore useful to minimize the stress and to obtain a slower colonization process to observe gradually the impact of bacterial establishment on the host metabolism. In this manuscript, we describe a procedure to assess the modification of hepatic metabolism during a gradual colonization process using a non-destructive metabolic profiling technique. We propose to monitor gut microbial colonization by assessing the gut microbial metabolic activity reflected by the urinary excretion of microbial co-metabolites by (1)H NMR-based metabolic profiling. This allows an appreciation of the stability of gut microbial activity beyond the stable establishment of the gut microbial ecosystem usually assessed by monitoring fecal bacteria by DGGE (denaturing gradient gel electrophoresis). The colonization takes place in a conventional open environment and is initiated by a dirty litter soiled by conventional animals, which will serve as controls. Rodents being coprophagous animals, this ensures a homogenous colonization as previously described. Hepatic metabolic profiling is measured directly from an intact liver biopsy using (1)H High Resolution Magic Angle Spinning NMR spectroscopy. This semi-quantitative technique offers a quick way to assess, without damaging the cell structure, the major metabolites such as triglycerides, glucose and glycogen in order to further estimate the complex interaction between the colonization process and the hepatic metabolism. This method can also be applied to any tissue biopsy. PMID:22215201
Tracking Stable Isotope Enrichment in Tree Seedlings with Solid-State NMR Spectroscopy
Norris, Charlotte E.; Quideau, Sylvie A.; Landhõusser, Simon M.; Bernard, Guy M.; Wasylishen, Roderick E.
Enriching plant tissues with 13C and 15N isotopes has provided long-lasting, non-reactive tracers to quantify rates of terrestrial elemental fluxes (e.g., soil organic matter decomposition). However, the molecular location and level of isotope enrichment may differ among plant tissues. This factor is central to the integrity and interpretation of tracer data, but is seldom considered in experiments. We propose a rapid, non-destructive method to quantify molecular isotope allocation using solid-state 13C and 15N nuclear magnetic resonance spectroscopy. With this method, we tracked and quantified the fate of multiple pulses of 13CO2(g) and K 15NO3(l) in boreal tree seedling roots and leaves as a function of time. Results show that initial preferential 13C carbohydrate enrichment in the leaves was followed by redistribution to more complex compounds after seven days. While 13C allocation within the roots was uniform across molecules, 15N results indicate an initial enrichment of amine molecules after two hours. PMID:23056911
Multiple quantum filtered 23Na NMR spectroscopy of the isolated, perfused rat liver.
Colet, J M; Bansal, N; Malloy, C R; Sherry, A D
Isolated, perfused rat livers were examined by single-quantum (SQ) and double-quantum-filtered (DQ-filtered) 23Na spectroscopy during prolonged global ischemia and during perfusion with ouabain, low-buffer potassium, or lithium-enriched buffer. Baseline separation of the intracellular (Na(i)+) and extracellular (Na(e)+) sodium resonances using TmDOTP5- allowed a direct comparison of temporal changes in SQ versus DQ-filtered Na(i)+. The SQ Na(i)+ signal increased approximately 150% during the first 15 min of global ischemia and then remained relatively constant over the next 45 min, while the DQ-filtered signal steadily increased approximately 400% over the same 60 min period. In similar experiments in which all perfusate sodium was replaced by lithium, the DQ-filtered Na(i)+ signal increased approximately 180% over a similar period of ischemia. Exposure of livers to ouabain also resulted in larger increases in DQ-filtered versus SQ signal of Na(i)+. The approximately 290% increase in DQ-filtered sodium observed during perfusion of livers with a hypokalemic buffer (1.2 mM K+) could be completely reversed by continued perfusion with a buffer containing normal levels of K+ (4.7 mM). These data suggest that the DQ-filtered Na(i)+ signal of liver does not simply report an increase in [Na(i)+], but may be exquisitely sensitive to other intracellular events initiated by altered physiology. PMID:10371444
Internuclear 31P-51V Distance Measurements in Polyoxoanionic Solids Using REAPDOR NMR Spectroscopy
Huang, Wenlin; Vega, Alexander J.; Gullion, Terry; Polenova, Tatyana
We report the first results establishing REAPDOR experiments for distance measurements between a spin-1/2 (31P) and spin-7/2 (51V) pair in a series of vanadium-substituted polyoxoanionic solids from the Keggin and Wells-Dawson families. We have quantitatively measured 31P-51V distances in mono-vanadium substituted K4PVW11O40, 1-K7P2VW17O62, and 4-K7P2VW17O62. Numerical simulations of the experimental data yield very good agreement with the averaged P-W/P-V distances determined from the X-ray diffraction measurements in the same or related compounds. REAPDOR is therefore a very sensitive P-V distance probe anticipated to be especially useful in the absence of long-range order. Our results suggest that REAPDOR spectroscopy could be broadly applicable for interatomic distance measurements in other spin-7/2-spin-1/2 nuclear pairs. PMID:17918932
Kinetic analysis of glycogen turnover: relevance to human brain 13C-NMR spectroscopy
DiNuzzo, Mauro
A biophysical model of the glycogen molecule is developed, which takes into account the points of attack of synthase and phosphorylase at the level of the individual glucose chain. Under the sole assumption of steric effects governing enzyme accessibility to glucosyl residues, the model reproduces the known equilibrium structure of cellular glycogen at steady state. In particular, experimental data are reproduced assuming that synthase (1) operates preferentially on inner chains of the molecule and (2) exhibits a faster mobility than phosphorylase in translocating from an attacked chain to another. The model is then used to examine the turnover of outer versus inner tiers during the labeling process of isotopic enrichment (IE) experiments. Simulated data are fitted to in vivo 13C nuclear magnetic resonance spectroscopy measurements obtained in the human brain under resting conditions. Within this experimental set-up, analysis of simulated label incorporation and retention shows that 7% to 35% of labeled glucose is lost from the rapidly turning-over surface of the glycogen molecule when stimulation onset is delayed by 7 to 11.5?hours after the end of [1-13C]glucose infusion as done in actual procedures. The substantial label washout before stimulation suggests that much of the subsequent activation-induced glycogenolysis could remain undetected. Overall, these results show that the molecular structure significantly affects the patterns of synthesis and degradation of glycogen, which is relevant for appropriate design of labeling experiments aiming at investigating the functional roles of this glucose reserve. PMID:23756693
Impact of salbutamol on muscle metabolism assessed by (31) P NMR spectroscopy.
Decorte, N; Lamalle, L; Carlier, P G; Giacomini, E; Guinot, M; Levy, P; Verges, S; Wuyam, B
The potential ergogenic effects of oral salbutamol intake were demonstrated for decades but the underlying mechanisms remain to elucidate. We hypothesized that improved exercise performance after acute oral salbutamol administration is associated with changes in muscle metabolism. Twelve healthy, nonasthmatic, moderately trained, male subjects were recruited to compare in a double-blind crossover randomized study, an oral dose of salbutamol (4?mg) and a placebo. After treatment administration, subjects performed repetitive plantar flexions to exhaustion in a 3T magnet. Continuous (31) P nuclear magnetic resonance spectroscopy assessment of the calf muscles was performed at rest, during exercise, and during recovery. No significant difference between treatments was detected in metabolite concentration at rest (P?>?0.05). Creatine phosphate and inorganic phosphate changes during and immediately after exercise were similar between treatments (P?>?0.05). Intramuscular pH (pHi) was significantly higher at rest, at submaximal exercise but not at exhaustion with salbutamol (pHi at 50% of exercise duration, 6.8?▒?0.1/6.9?▒?0.1 for placebo and salbutamol, respectively, P?0.05). The maximal power (28?▒?7?W/23?▒?7?W; P?=?0.001) and total work (1702?▒?442?J/1381?▒?432?J; P?=?0.003) performed during plantar flexions were significantly increased with salbutamol. Salbutamol induced significant improvement in calf muscle endurance with similar metabolic responses during exercise, except slight differences in pHi. Other mechanisms than changes in muscle metabolism may be responsible for the ergogenic effect of salbutamol administration. PMID:25230069
Complete assignments of (1)H and (13)C NMR data for two new sesquiterpenes from Cyperus rotundus L.
Xu, Yan; Zhang, Hong-Wu; Wan, Xiao-Chun; Zou, Zhong-Mei
Two new sesquiterpenes, epi-guaidiol A (1) and sugebiol (3), together with four known sesquiterpenes, guaidiol A(2), sugetriol triacetate (4), cyperenoic acid (5), and cyperotundone (6) were isolated from the rhizomes of Cyperus rotundus L. Their structures were identified by MS and NMR experiments, and the complete assignments of (1)H and (13)C NMR data for two new sesquiterpenes were obtained by the aid of two-dimensional (2D) NMR techniques, including HSQC, HMBC, (1)H-(1)HCOSY and nuclear overhauser enhancement spectroscopy(NOESY). PMID:19288546
Evidence for altered metabolic pathways during environmental stress: (1)H-NMR spectroscopy based metabolomics and clinical studies on subjects of sea-voyage and Antarctic-stay.
Yadav, Anand Prakash; Chaturvedi, Shubhra; Mishra, Kamla Prasad; Pal, Sunil; Ganju, Lilly; Singh, Shashi Bala
The Antarctic context is an analogue of space travel, with close similarity in ambience of extreme climate, isolation, constrained living spaces, disrupted sleep cycles, and environmental stress. The present study examined the impact of the harsh habitat of Antarctica on human physiology and its metabolic pathways, by analyzing human serum samples, using (1)H-NMR spectroscopy for identification of metabolites; and quantifying other physiological and clinical parameters for correlation between expression data and metabolite data. Sera from seven adult males (of median age 36years) who participated in this study, from the 28th Indian Expeditionary group to the Antarctica station Maitri, were collected in chronological sequence. These included: i) baseline control; ii) during ship journey; iii) at Antarctica, in the months of March, May, August and November; to enable study of temporal evolution of monitored physiological states. 29 metabolites in serum were identified from the 400MHz (1)H-NMR spectra. Out of these, 19 metabolites showed significant variations in levels, during the ship journey and the stay at Maitri, compared to the base-line levels. Further biochemical analysis also supported these results, indicating that the ship journey, and the long-term Antarctic exposure, affected kidney and liver functioning. Our metabolite data highlights for the first time the effect of environmental stress on the patho-physiology of the human system. Multivariate analysis tools were employed for this metabonomics study, using (1)H-NMR spectroscopy. PMID:24910139
YPdSn and YPd2Sn: Structure, 89Y solid state NMR and 119Sn M÷ssbauer spectroscopy
NASA Astrophysics Data System (ADS)
H÷ting, Christoph; Eckert, Hellmut; Langer, Thorsten; Schellenberg, Inga; P÷ttgen, Rainer
The stannides YPdSn and YPd2Sn were synthesized by high-frequency melting of the elements in sealed tantalum tubes. Both structures were refined on the basis of single crystal X-ray diffractometer data: TiNiSi type, Pnma, a=715.4(1), b=458.8(1), c=789.1(1) pm, wR2=0.0461, 510 F2 values, 20 variables for YPdSn and MnCu2Al type, Fm3barm, a=671.44(8), wR2=0.0740, 55 F2 values, 5 parameters for YPd2Sn. The yttrium atoms in the new stannide YPdSn are coordinated by two tilted Pd3Sn3 hexagons (ordered AlB2 superstructure). In the Heusler phase YPd2Sn each yttrium atom has octahedral tin coordination and additionally eight palladium neighbors. The cubic site symmetry of yttrium is reflected in the 119Sn M÷ssbauer spectrum which shows no quadrupole splitting. In contrast, YPdSn shows a single signal at ?=1.82(1) mm/s subjected to quadrupole splitting of ?EQ=0.93(1) mm/s. Both compounds have been characterized by high-resolution 89Y solid state NMR spectroscopy, which indicates the presence of strong Knight shifts. The spectrum of YPd2Sn is characterized by an unusually large linewidth, suggesting the presence of a Knight shift distribution reflecting local disordering effects. The range of 89Y Knight shifts of several binary and ternary intermetallic yttrium compounds is briefly discussed.
Sensitivity of force-detected NMR spectroscopy with resonator-induced polarization
NASA Astrophysics Data System (ADS)
Butler, Mark C.; Weitekamp, Daniel P.
In the low-temperature regime where the thermal polarization P is of order unity and spin-lattice relaxation is ōfrozen out,ö resonator-induced relaxation can be used to polarize a nuclear-spin sample for optimal detection sensitivity. We characterize the potential of resonator-induced polarization for enhancing the sensitivity of nuclear-magnetic-resonance spectroscopy. The sensitivities of two detection schemes are compared, one involving detection of a polarized sample dipole and the other involving detection of spin-noise correlations in an unpolarized sample. In the case where the dominant noise source is instrument noise associated with resonator fluctuations and with detection of the mechanical motion, a simple criterion can be used to compare the two schemes. Polarizing the sample improves sensitivity when P is larger than the signal-to-noise ratio for detection of a fully-polarized spin during a single transient. Even if the instrument noise is decreased to a level near the quantum-mechanical limit, it is larger than spin noise for unpolarized samples containing up to a few tens of nuclei. Under these conditions, spin polarization of order unity would enhance spectroscopic detection sensitivity by an order of magnitude or more. In the limiting case where signal decay is due to resonator-induced dissipation during ideal spin locking, and where resonator fluctuations are the noise source, the only parameter of the spin-resonator system that affects the sensitivity per spin is the ratio of frequency to temperature. A balance between the coupling strength, the noise power, and the signal lifetime causes the cancellation of other parameters from the sensitivity formula. Partial cancellation of parameters, associated with a balance between the same three quantities, occurs more generally when the resonator is both the dominant noise source and the dominant source of signal decay. An intrinsic sensitivity limit exists for resonant detection of coherent spin evolution, due to the fact that the detector causes signal decay by enhancing the spins' spontaneous emission. For a single-spin sample, the quantum-limited signal-to-noise ratio for resonant detection is 1/3. In contrast to the sensitivity, the time required for sample polarization between transients depends strongly on resonator parameters. We discuss resonator design and show that for a torsional resonator, the coupling is optimal when the resonator's magnetization remains aligned with the applied field during the mechanical oscillations.
Orientation and Dynamics of an Antimicrobial Peptide in the Lipid Bilayer by Solid-State NMR Spectroscopy
Hong, Mei
Orientation and Dynamics of an Antimicrobial Peptide in the Lipid Bilayer by Solid-State NMR of Microbiology, University of Iowa College of Medicine, Iowa City, Iowa 52242 USA ABSTRACT The orientation-spectrum bactericidal activity. 15 N NMR spectra of oriented ovispirin reconstituted into synthetic phospholipids show
Chemical structure and heterogeneity differences of two lignins from loblolly pine as investigated by advanced solid-state NMR spectroscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
Advanced solid-state NMR was employed to investigate differences in chemical structure and heterogeneity between milled wood lignin (MWL) and residual enzyme lignin (REL). Wiley and conventional milled woods were also studied. The advanced NMR techniques included 13C quantitative direct polarization...
Technology Transfer Automated Retrieval System (TEKTRAN)
A recently described plant cell wall dissolution system has been logically modified to utilize perdeuterated solvents to allow direct in-nmr-tube dissolution and high-resolution solution-state NMR of the whole cell wall without derivatization. Finely ground cell wall material dissolves in a solvent ...
A method for in vivo assessment of reversible rat pancreatic ischemia using 31P NMR spectroscopy at 2.0 tesla.
Siech, M; Sotak, C H; Letko, G; Davis, M A
A surgical method is described which allows in vivo assessment of reversible rat pancreatic ischemia using 31P NMR spectroscopy at 2.0 T. Phosphorous-31 NMR spectra acquired during the ischemic period show the expected increase in inorganic phosphate with a concomitant decrease in ATP levels and pH as compared to controls. Upon reperfusion, inorganic phosphate and ATP returned to control levels while pH recovered to a more alkaline value. This method provides a means of studying in vivo changes in high energy metabolite associated with acute pancreatitis (AP) and maintains the secretory ability of the gland so that different forms of AP, such as those arising from pancreatic juice edema, can be studied. PMID:7791556
Elimination of surface signals by a surface-spoiling magnetic field gradient. Theoretical optimization and application to human in vivo NMR spectroscopy
NASA Astrophysics Data System (ADS)
Jehenson, P.; Bloch, G.
W. Chen and J. J. H. Ackerman ( J. Magn. Reson.82, 655, 1989; NMR Biomed.2, 267, 1989) used a superficial magnetic field gradient to eliminate surface signals when observing rat liver in vivo. We have developed a method for computing the optimal gradient coil for a given in vivo application. An analytical solution for the magnetic field created by a planar array of antiparallel current elements was derived for the calculations. The surface-signal suppression obtained by gradient coils of various sizes is presented in a synthetic plot which directly provides the electrical and geometrical parameters of the optimal coil as well as the residual signal in the deep-lying region of interest. This approach was applied to in vivo31P and 31C spectroscopy of the human liver. Hepatic glycogen was detected by natural-abundance 13C NMR without contamination from muscle glycogen, and physiological variation during starvation could be observed.
Phosphorus speciation in agro-industrial byproducts: sequential fractionation, solution (31)P NMR, and P K- and L(2,3)-edge XANES spectroscopy.
Negassa, Wakene; Kruse, Jens; Michalik, Dirk; Appathurai, Narayana; Zuin, Lucia; Leinweber, Peter
Little is known about P species in agro-industrial byproducts from developing countries, which may be either pollutants or valuable soil amendments. The present study speciated P in dry (COD) and wet (COW) coffee, sisal (SIS), barley malt (BEB) and sugar cane processing (FIC) byproducts, and filter cakes of linseed (LIC) and niger seed (NIC)with sequential fractionation, solution (31)P nuclear magnetic resonance (NMR) spectroscopy, and P K- and L(2,3)-edge X-ray absorption near-edge structure (XANES) spectroscopy. The sequential P fractionation recovered 59% to almost 100% of total P (P(t)), and more than 50% of P(t) was extracted by H(2)O and NaHCO(3) in five out of seven samples. Similarly, the NaOH + EDTA extraction for solution (31)P NMR recovered 48-94% of P(t). The (31)P NMR spectra revealed orthophosphate (6-81%), pyrophosphate (0-10%), and orthophosphate monoesters (6-94%). Orthophosphate predominated in COD, COW, SIS, and FIC, whereas BEB, UC, and NIC were rich in orthophosphate monoesters. The concentrations of P(i), and P(o) determined in the sequential and NaOH + EDTA extractions and (31)P NMR spectra were strongly and positively correlated (r = 0.88-1.00). Furthermore, the P K- and L(2,3)-edge XANES confirmed the H(2)SO(4)--P(i) detected in the sequential fractionation by unequivocal identification of Ca--P phases in a few samples. The results indicate that the combined use of all four analytical methods is crucial for comprehensive P speciation in environmental samples and the application of these byproducts to soil. PMID:20146464
Covalent binding of reduced metabolites of [{sup 15}N{sub 3}]TNT to soil organic matter during a bioremediation process analyzed by {sup 15}N NMR spectroscopy
Achtnich, C.; Fernandes, E.; Bollag, J.M.; Knackmuss, H.J.; Lenke, H.
Evidence is presented for the covalent binding of biologically reduced metabolites of 2,4,6-{sup 15}N{sub 3}-trinitrotoluene (TNT) to different soil fractions, using liquid {sup 15}N NMR spectroscopy. A silylation procedure was used to release soil organic matter from humin and whole soil for spectroscopic measurements. TNT-contaminated soil was spiked with 2,4,6-{sup 15}N{sub 3}-trinitrotoluene and {sup 14}C-ring labeled TNT, before treatment in a soil slurry reactor. During the anaerobic/aerobic incubation the amount of radioactivity detected in the fulvic and humic acid fractions did not change significantly whereas the radioactivity bound to humin increased to 71%. The {sup 15}N NMR spectra of the fulvic acid samples were dominated by a large peak that corresponded to aliphatic amines or ammonia. In the early stages of incubation, {sup 15}N NMR analysis of the humic acids indicated bound azoxy compounds. The signals arising from nitro and azoxy groups disappeared with further anaerobic treatment. At the end of incubation, the NMR shifts showed that nitrogen was covalently bound to humic acid as substituted amines and amides. The NMR spectra of the silylated humin suggest formation of azoxy compounds and imine linkages. Bound metabolites possessing nitro groups were also detected. Primary amines formed during the anaerobic incubation disappeared during the aerobic treatment. Simultaneously, the amount of amides and tertiary amines increased. Nitro and azoxy groups of bound molecules were still present in humin at the end of the incubation period. Formation of azoxy compounds from partially reduced TNT followed by binding and further reduction appears to be an important mechanism for the immobilization of metabolites of TNT to soil.
Characterization of the dynamics in the protonic conductor CsH?PO? by ╣?O solid-state NMR spectroscopy and first-principles calculations: correlating phosphate and protonic motion.
Kim, Gunwoo; Griffin, John M; Blanc, Frķdķric; Haile, Sossina M; Grey, Clare P
(17)O NMR spectroscopy combined with first-principles calculations was employed to understand the local structure and dynamics of the phosphate ions and protons in the paraelectric phase of the proton conductor CsH2PO4. For the room-temperature structure, the results confirm that one proton (H1) is localized in an asymmetric H-bond (between O1 donor and O2 acceptor oxygen atoms), whereas the H2 proton undergoes rapid exchange between two sites in a hydrogen bond with a symmetric double potential well at a rate ?10(7) Hz. Variable-temperature (17)O NMR spectra recorded from 22 to 214 ░C were interpreted by considering different models for the rotation of the phosphate anions. At least two distinct rate constants for rotations about four pseudo C3 axes of the phosphate ion were required in order to achieve good agreement with the experimental data. An activation energy of 0.21 ▒ 0.06 eV was observed for rotation about the P-O1 axis, with a higher activation energy of 0.50 ▒ 0.07 eV being obtained for rotation about the P-O2, P-O3(d), and P-O3(a) axes, with the superscripts denoting, respectively, dynamic donor and acceptor oxygen atoms of the H-bond. The higher activation energy of the second process is most likely associated with the cost of breaking an O1-H1 bond. The activation energy of this process is slightly lower than that obtained from the (1)H exchange process (0.70 ▒ 0.07 eV) (Kim, G.; Blanc, F.; Hu, Y.-Y.; Grey, C. P. J. Phys. Chem. C 2013, 117, 6504-6515) associated with the translational motion of the protons. The relationship between proton jumps and phosphate rotation was analyzed in detail by considering uncorrelated motion, motion of individual PO4 ions and the four connected/H-bonded protons, and concerted motions of adjacent phosphate units, mediated by proton hops. We conclude that, while phosphate rotations aid proton motion, not all phosphate rotations result in proton jumps. PMID:25732257
Complete proton and carbon-13 NMR assignment of the alkaloid geopyrotoxin through the use of homonuclear Hartmann-Hahn and two-dimensional NMR spectroscopy
Edwards, M.W.; Bax, A.
Three different types of modern NMR techniques have been used to obtain a complete proton and carbon-13 assignment of the alkaloid geopyrotoxin. In addition to the two-dimensional phase-sensitive homo- and heteronuclear shift correlation methods, use of the recently proposed one-dimensional homonuclear Hartmann-Hahn difference experiment was crucial for obtaining the required long-range connectivity. Guidelines are presented for optimal use of these techniques. Experiments were performed at 500-MHz /sup 1/H frequency, using 8 mg of sample. 53 references, 7 figures, 1 table.
Mixed micelles of Triton X-100, sodium dodecyl dioxyethylene sulfate, and synperonic l61 investigated by NOESY and diffusion ordered NMR spectroscopy.
Denkova, Pavletta S; Van Lokeren, Luk; Willem, Rudolph
Mixed micelles formed from nonionic surfactant Triton X-100 (TX100), anionic surfactant sodium dodecyl dioxyethylene sulfate (SDP2S), and triblock copolymer Synperonic L61 (SL61) were investigated by 1H NMR spectroscopy. The size and shape of the aggregates were determined by diffusion ordered NMR spectroscopy (DOSY), while 2D nuclear Overhauser enhanced spectroscopy (NOESY) NMR was used to study the mutual spatial arrangement of the surfactant molecules in the aggregated state. An average micellar hydrodynamic radius of 3.6 nm, slightly increasing upon increasing TX100 molar fraction, was found for the mixed systems without additives. Addition of SL61 to the mixed micellar systems results in a slight increase of micellar radii. In the presence of AlCl3, an increase of TX100/SDP2S micellar sizes from 4 to 10 nm was found when increasing the SDP2S molar fraction. The mixed TX100/SDP2S micelles in the presence of both AlCl3 and polymer SL61 are almost spherical, with a radius of 4.5 nm. 2D NOESY data reveal that, as the individual TX100 micelles, mixed TX100/SDP2S and TX100/SDP2S/SL61/AlCl3 micelles also have a multilayer structure, with partially overlapping internal and external layers of TX100 molecules. In these mixed micelles, the SDP2S molecules are located at the level of the external layer of TX100 molecules, whereas the SL61 polymer is partially incorporated inside of the micellar core. PMID:19385612
Analysis of the Composition of Lipid in Human Meibum from Normal Infants, Children, Adolescents, Adults, and Adults with Meibomian Gland Dysfunction Using 1H-NMR Spectroscopy
Shrestha, Rashmi K.; Foulks, Gary N.; Yappert, Marta C.; Milliner, Sarah E.
Purpose. This study represents a first step toward the evaluation of possible compositional differences in meibum from normal donors (Mn) and donors with meibomian gland dysfunction (Md) by 1H-NMR spectroscopy. The results highlight the applicability of 1H-NMR spectroscopy for the quantitative analysis of waxes, cholesteryl esters, and glycerides in meibum lipid (ML). Methods. Meibum was obtained from 41 normal donors and 51 donors with meibomian gland dysfunction (MGD). 1H-NMR spectroscopy was used to quantify the amount of waxes, glycerides, and cholesteryl esters in human meibum. Results. The relative amount of cholesteryl esters in Mn increased with age and was 40% (P < 0.05) lower in Md. Interestingly, the relative levels of cholesteryl esters in infant meibum were comparable to those in Md. The relative amounts of glycerides were not affected significantly by age or MGD. Conclusions. The changes in cholesteryl ester could be used as a molecular marker for MGD and could potentially be applied to follow the efficacy of drug therapy in the treatment of MGD. The similarity of the levels of cholesteryl esters in infant meibum and Md suggests that the relative amounts of these meibum components alone are unlikely to be responsible for the increased stability of the infant tear film and decreased stability of the tear film with MGD. This study reveals the complexity of human MLs and the changes that occur with age and disease. Understanding the factors that lead to such variations is of utmost relevance in the design of effective therapies. PMID:21849420
Investigation of lipase-catalysed hydrolysis of naproxen methyl ester: use of NMR spectroscopy methods to study substrate-enzyme interaction.
Cernia, E; Delfini, M; Di Cocco, E; Palocci, C; Soro, S
(+/-)-2-(6-Methoxy-2-naphthyl)propionic acid methyl ester (methyl ester of Naproxen), the precursor of therapeutically important nonsteroidal anti-inflammatory drugs (NSAIDs) was enantioselectively hydrolysed using as biocatalyst Candida rugosa lipase. In research aimed at studying the structure-activity relationship (SAR), NMR spectroscopy methods were employed to identify which Naproxen molecular moiety was essential to the substrate-enzyme interaction. The experimental results, in agreement with previous computer modelling studies and reported kinetic data, gave new information on the enzyme-substrate complex formation in solution. PMID:12392706
Preparation of cold ions in strong magnetic field and its application to gas-phase NMR spectroscopy
NASA Astrophysics Data System (ADS)
Fuke, K.; Ohshima, Y.; Tona, M.
Nuclear Magnetic Resonance (NMR) technique is widely used as a powerful tool to study the physical and chemical properties of materials. However, this technique is limited to the materials in condensed phases. To extend this technique to the gas-phase molecular ions, we are developing a gas-phase NMR apparatus. In this note, we describe the basic principle of the NMR detection for molecular ions in the gas phase based on a Stern-Gerlach type experiment in a Penning trap and outline the apparatus under development. We also present the experimental procedures and the results on the formation and the manipulation of cold ions under a strong magnetic field, which are the key techniques to detect the NMR by the present method.
Use of 19F NMR Spectroscopy for Measurement of Cerebral Blood Flow: A Comparative Study Using Microspheres
David Barranco; Leslie N. Sutton; Sandra Florin; Joel Greenberg; Teresa Sinnwell; Laszlo Ligeti; Alan C. McLaughlin
Summary: 19F NMR was used to determine washout curves of an inert, diffusible gas (CHF3) from the cat brain. The cerebral blood flow was estimated from a bi- or tri-phasic fit to the deconvoluted wash-out curve, using the Kety-Schmidt approach. Cerebral blood flow values determined by 19F NMR show the expected responsiveness to alterations in Paco2, but are approximately 28%
Studies On Competitive Interactions and Blending Order of Engine Oil Additives by Variable Temperature P-NMR and IR Spectroscopy
G. S. Kapur; A. Chopra; A. S. Sarpal; S. S. V. Ramakumar; S. K. Jain
Interactions between various engine oil additives including dispersant, detergent, antiwear\\/antioxidant, and viscosity index improvers have been investigated through changes in the P-NMR and IR spectra. Significant changes in the P-NMR and IR spectra of zinc dialkyldithiophosphate (ZDDP) have been observed by varying the blending order of additives. Dispersant-detergent (polyisobutylene succinimide-calcium overbased sulfonate) and viscosity index improver-detergent (dispersant olefin copolymer-calcium overbased
NMR Investigations of Nanostructured Ceramics
M. Edgar; M. Schubert; H. H. Limbach
Nanostructured mesoporous silicates displaying hexagonally arranged channels, templated using a liquid crystal mesophase, were investigated using H-2 and N-15 NMR spectroscopy. It is shown that N-I5 MAS NMR spec- troscopy allows to estimate the surface acidity of mesoporous materials by measuring the N-H bond length via the N-15 chemical shift. Further, H-2 and N-15 NMR spectroscopy identify significant differences between
Quantitative evaluation of the lactate signal loss and its spatial dependence in press localized (1)H NMR spectroscopy.
Jung, W I; Bunse, M; Lutz, O
Localized (1)H NMR spectroscopy using the 90 degrees -t(1)-180 degrees -t(1)+t(2)-180 degrees -t(2)-Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t(1) and t(2). The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t(1)=t(2)) at an echo time of 2/J (approximately 290 ms). Calculations have shown that this signal loss is related to the pulse angle distributions produced by the two refocusing pulses which leads to the creation of single quantum polarization transfer (PT) as well as to not directly observable states (NDOS) of the lactate AX(3) spin system: zero- and multiple-quantum coherences, and longitudinal spin orders. In addition, the chemical shift dependent voxel displacement (VOD) leads to further signal loss. By calculating the density operator for various of the echo times TE=n/J, n=1, 2, 3,..., we calculated quantitatively the contributions of these effects to the signal loss as well as their spatial distribution. A maximum signal loss of 75% can be expected from theory for the symmetrical PRESS sequence and TE=2/J for Hamming filtered sinc pulses, whereby 47% are due to the creation of NDOS and up to 28% arise from PT. Taking also the VOD effect into account (2 mT/m slice selection gradients, 20-mm slices) leads to 54% signal loss from NDOS and up to 24% from PT, leading to a maximum signal loss of 78%. Using RE-BURP pulses with their more rectangular pulse angle distributions reduces the maximum signal loss to 44%. Experiments at 1.5 T using a lactate solution demonstrated a maximum lactate signal loss for sinc pulses of 82% (52% NDOS, 30% PT) at TE=290 ms using the symmetrical PRESS sequence. The great signal loss and its spatial distribution is of importance for investigations using a symmetrical PRESS sequence at TE=2/J. PMID:11567573
Quantitative Evaluation of the Lactate Signal Loss and Its Spatial Dependence in PRESS Localized 1H NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Jung, Wulf-Ingo; Bunse, Michael; Lutz, Otto
Localized 1H NMR spectroscopy using the 90░-t1-180░-t1+t2-180░-t2-Acq. PRESS sequence can lead to a signal loss for the lactate doublet compared with signals from uncoupled nuclei which is dependent on the choice of t1 and t2. The most striking signal loss of up to 78% of the total signal occurs with the symmetrical PRESS sequence (t1=t2) at an echo time of 2/J (?290 ms). Calculations have shown that this signal loss is related to the pulse angle distributions produced by the two refocusing pulses which leads to the creation of single quantum polarization transfer (PT) as well as to not directly observable states (NDOS) of the lactate AX3 spin system: zero- and multiple-quantum coherences, and longitudinal spin orders. In addition, the chemical shift dependent voxel displacement (VOD) leads to further signal loss. By calculating the density operator for various of the echo times TE=n/J, n=1, 2, 3, ģ, we calculated quantitatively the contributions of these effects to the signal loss as well as their spatial distribution. A maximum signal loss of 75% can be expected from theory for the symmetrical PRESS sequence and TE=2/J for Hamming filtered sinc pulses, whereby 47% are due to the creation of NDOS and up to 28% arise from PT. Taking also the VOD effect into account (2 mT/m slice selection gradients, 20-mm slices) leads to 54% signal loss from NDOS and up to 24% from PT, leading to a maximum signal loss of 78%. Using RE-BURP pulses with their more rectangular pulse angle distributions reduces the maximum signal loss to 44%. Experiments at 1.5 T using a lactate solution demonstrated a maximum lactate signal loss for sinc pulses of 82% (52% NDOS, 30% PT) at TE=290 ms using the symmetrical PRESS sequence. The great signal loss and its spatial distribution is of importance for investigations using a symmetrical PRESS sequence at TE=2/J.
Composite-180░ pulse-based symmetry sequences to recouple proton chemical shift anisotropy tensors under ultrafast MAS solid-state NMR spectroscopy
NASA Astrophysics Data System (ADS)
Pandey, Manoj Kumar; Malon, Michal; Ramamoorthy, Ayyalusamy; Nishiyama, Yusuke
There is considerable interest in the measurement of proton (1H) chemical shift anisotropy (CSA) tensors to obtain deeper insights into H-bonding interactions which find numerous applications in chemical and biological systems. However, the presence of strong 1H/1H dipolar interaction makes it difficult to determine small size 1H CSAs from the homogeneously broadened NMR spectra. Previously reported pulse sequences for 1H CSA recoupling are prone to the effects of radio frequency field (B1) inhomogeneity. In the present work we have carried out a systematic study using both numerical and experimental approaches to evaluate ?-encoded radio frequency (RF) pulse sequences based on R-symmetries that recouple 1H CSA in the indirect dimension of a 2D 1H/1H anisotropic/isotropic chemical shift correlation experiment under ultrafast magic angle spinning (MAS) frequencies. The spectral resolution and sensitivity can be significantly improved in both frequency dimensions of the 2D 1H/1H correlation spectrum without decoupling 1H/1H dipolar couplings but by using ultrafast MAS rates up to 70 kHz. We successfully demonstrate that with a reasonable RF field requirement (<200 kHz) a set of symmetry-based recoupling sequences, with a series of phase-alternating 270░0-90░180 composite-180░ pulses, are more robust in combating B1 inhomogeneity effects. In addition, our results show that the new pulse sequences render remarkable 1H CSA recoupling efficiency and undistorted CSA lineshapes. Experimental results on citric acid and malonic acid comparing the efficiencies of these newly developed pulse sequences with that of previously reported CSA recoupling pulse sequences are also reported under ultrafast MAS conditions.
An early transient increase of intracellular Na + may be one of the first components of the mitogenic signal. Direct detection by 23Na-NMR spectroscopy in quiescent 3T3 mouse fibroblasts stimulated by growth factors
Elisha Berman; Ilana Sharon; Henri Atlan
23Na-NMR spectroscopy was designed to allow for continuous recording of intracellular Na+ in 3T3 fibroblasts stimulated by serum growth-factors in the presence of ion transport inhibitors. The metabolic state of cells at rest and following stimulation was monitored by 31P-NMR spectra of ATP and related high-energy phosphates. The study demonstrates that early activation of ion transporters by addition of serum
NASA Technical Reports Server (NTRS)
Burum, D. P.; Elleman, D. D.; Rhim, W.
Method gives results approximating those of classical continuous-irradiation method but in less time. Method also makes it possible to measure chemical shifts and spin-lattice relaxation times with improved sensitivity. Equipment can be used for adiabatic demagnetization experiments, measurements of rotating-frame spin/lattice relaxation times, and accurate measurements of exact resonance points. When measuring relaxation times, pulse technique can be very effective since pulses may be limited in amplitude and length to prevent spin system from being driven into saturation.
Structural study of 2-(1-oxo-1 H-inden-3-yl)-2 H-indene-1,3-dione by DFT calculations, NMR and IR spectroscopy
NASA Astrophysics Data System (ADS)
Riahi, Siavash; Ganjali, Mohammad Reza; Moghaddam, Abdolmajid Bayandori; Norouzi, Parviz; Hosseiny Davarani, Saied Saeed
Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of 2-(1-oxo-1 H-inden-3-yl)-2 H-indene-1,3-dione (OID). Experimental studies were conducted on these parameters, including X-ray, FT-IR and 13C NMR spectroscopy. The optimized geometries of OID and its bonding characteristics as well as IR and NMR spectra have been calculated and analyzed. It was observed that the bond lengths and angles in the molecule, obtained by X-ray, IR and NMR at the level of theory, were in a good agreement with those of the experiment. The correlation between the theoretical and the experimental vibrational frequencies and the chemical shifts of the OID molecule were 0.994 and 0.991, respectively. The agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.
Modeling relationships among active components in black raspberry (Rubus occidentalis L.) fruit extracts using high-resolution (1)H nuclear magnetic resonance (NMR) spectroscopy and multivariate statistical analysis.
Wyzgoski, Faith J; Paudel, Liladhar; Rinaldi, Peter L; Reese, R Neil; Ozgen, Mustafa; Tulio, Artemio Z; Miller, A Raymond; Scheerens, Joseph C; Hardy, James K
A process was developed to ascertain the bioactive components of black raspberry (Rubus occidentalis L.) fruit extracts by relating chemical constituents determined by high-field nuclear magnetic resonance (NMR) spectroscopy to biological responses using partial least-squares regression analysis. To validate our approach, we outlined relationships between phenolic signals in NMR spectra and chemical data for total monomeric anthocyanin (TMA) content and antioxidant capacity by the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Anthocyanins, cyanidin 3-O-rutinoside (Cy 3-rut), cyanidin 3-O-(2(G))-xylosylrutinoside (Cy 3-xylrut), and cyanidin 3-O-glucoside (Cy 3-glc), were significant contributors to the variability in assay results, with the two most important NMR bins corresponding to the methyl peaks in Cy 3-rut (6''') and/or Cy 3-xylrut (6(IV)). Many statistically important bins were common among assay models, but differences in structure-activity relationships resulted in changes in bin ranking. The specificity of these results supported the application of the process to investigate relationships among health-beneficial natural products and potential biological activity. PMID:20192269
Toward a biorelevant structure of protein kinase C bound modulators: design, synthesis, and evaluation of labeled bryostatin analogues for analysis with rotational echo double resonance NMR spectroscopy.
Loy, Brian A; Lesser, Adam B; Staveness, Daryl; Billingsley, Kelvin L; Cegelski, Lynette; Wender, Paul A
Protein kinase C (PKC) modulators are currently of great importance in preclinical and clinical studies directed at cancer, immunotherapy, HIV eradication, and Alzheimer's disease. However, the bound conformation of PKC modulators in a membrane environment is not known. Rotational echo double resonance (REDOR) NMR spectroscopy could uniquely address this challenge. However, REDOR NMR requires strategically labeled, high affinity ligands to determine interlabel distances from which the conformation of the bound ligand in the PKC-ligand complex could be identified. Here we report the first computer-guided design and syntheses of three bryostatin analogues strategically labeled for REDOR NMR analysis. Extensive computer analyses of energetically accessible analogue conformations suggested preferred labeling sites for the identification of the PKC-bound conformers. Significantly, three labeled analogues were synthesized, and, as required for REDOR analysis, all proved highly potent with PKC affinities (?1 nM) on par with bryostatin. These potent and strategically labeled bryostatin analogues are new structural leads and provide the necessary starting point for projected efforts to determine the PKC-bound conformation of such analogues in a membrane environment, as needed to design new PKC modulators and understand PKC-ligand-membrane structure and dynamics. PMID:25710634
Lithium dynamics in the fast ionic conductor Li0.18 La0.61 TiO3 probed by 7Li NMR spectroscopy
NASA Astrophysics Data System (ADS)
Rivera, A.; Sanz, J.
Lithium dynamics in the Li0.18La0.61TiO3 perovskite quenched from 1623K has been analyzed by means of Li7 Nuclear magnetic resonance (NMR) spectroscopy and neutron powder diffraction. The Rietveld analysis of the diffraction pattern shows rhombohedral symmetry with lithium ions occupying square windows that connect contiguous A sites of the perovskite. The hopping of lithium ions through these windows produces the line narrowing detected above 170K in Li7 NMR spectra. Deconvolution of NMR spectra shows the existence of two lithium species that exchange their positions along the temperature range 250-350K . In this temperature range, a plateau is detected in T2-1 plots, which has been ascribed to the existence of two-dimensional motions of lithium in ordered domains of the perovskite. Evidence of this limited motion comes from the frequency dependence of the spin-lattice relaxation rates measured at the high temperature side of the asymmetric 1/T1 maximum ( ???1 regime). T1? measurements indicate that there is a slower motion of lithium with a characteristic time of 3ū10-6s at room temperature, assigned to isotropic three-dimensional diffusion.
Synthesis, characterization, and {sup 1}H and {sup 71}Ga MAS NMR spectroscopy of a novel Mg/Ga double layered hydroxide
Aramendia, M.A.; Borau, V.; Jimenez, C. [Cordoba Univ. (Spain)] [and others] [Cordoba Univ. (Spain); and others
A new brucite-like layered Mg/Ga double hydroxide (LDH) of composition [Mg{sub 0.174}Ga{sub 0.256}(OH){sub 2}](CO{sub 3}){sub 0}.134 {center_dot}mH{sub 2}O was synthesized by coprecipitation at pH 10. The hydroxide and the mixed oxides resulting from its thermal decomposition at 523, 823 and 1073K were characterized by X-ray diffraction, diffuse reflectance infrared spectroscopy, high-resolution solid-state nuclear magnetic resonance (MAS NMR), and thermogravimetric analysis. The surface properties of the solid (specific surface) and its basicity were also determined. The Mg /Ga LDH was found to be stable up to 523 K and to decompose into a mixture of periclase MgO and amorphous Ga{sub 2}O{sub 3} at 823 K. Its changes with temperature were monitored by using {sup 1}H and {sup 71}Ga MAS NMR; {sup 1}H MAS NMR spectra revealed the loss of interlayer OH groups supporting the brucite-like structure on calcination at 823 K.
Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy
NASA Astrophysics Data System (ADS)
Ghassemzadeh, L.; Kreuer, K. D.; Maier, J.; M³ller, K.
Chemical degradation and stability of perfluorosulfonic acid (PFSA) ionomers against radical attack were investigated by an (ex situ) Fenton test. Solid-state and solution NMR as well as ATR-FTIR studies were performed on the samples before and after the Fenton reaction. By changing the concentration of the Fenton's solution it is found that the metallic catalyst (Fe2+) is a critical factor which may affect the solid-state NMR results. After adjusting the experimental conditions, i.e., by reducing the Fe2+ concentration, it was possible to detect by solid-state 19F NMR spectroscopy the structural changes of the perfluorosulfonic acid ionomers during the ex situ Fenton test. A comparative study was made on the degradation of Nafion and Hyflon Ion membranes which differ in the length of the side chains. It is shown that the Hyflon Ion membrane with shorter side chains is more stable against side chain attack, most probably because of the absence of an additional tertiary carbon in the side chain. At the same time, there is evidence for enhanced main chain degradation in membranes with unprotected backbone chain ends.
Constant time INEPT CT-HSQC (CTi-CT-HSQC) - A new NMR method to measure accurate one-bond J and RDCs with strong 1H-1H couplings in natural abundance.
Yu, Bingwu; van Ingen, Hugo; Freedberg, Dar¾n I
Strong (1)H-(1)H coupling can significantly reduce the accuracy of (1)J(CH) measured from frequency differences in coupled HSQC spectra. Although accurate (1)J(CH) values can be extracted from spectral simulation, it would be more convenient if the same accurate (1)J(CH) values can be obtained experimentally. Furthermore, simulations reach their limit for residual dipolar coupling (RDC) measurement, as many significant, but immeasurable RDCs are introduced into the spin system when a molecule is weakly aligned, thus it is impossible to have a model spin system that truly represents the real spin system. Here we report a new J modulated method, constant-time INEPT CT-HSQC (CTi-CT-HSQC), to accurately measure one-bond scalar coupling constant and RDCs without strong coupling interference. In this method, changing the spacing between the two 180░ pulses during a constant time INEPT period selectively modulates heteronuclear coupling in quantitative J fashion. Since the INEPT delays for measuring one-bond carbon-proton spectra are short compared to (3)J(HH), evolution due to (strong) (1)H-(1)H coupling is marginal. The resulting curve shape is practically independent of (1)H-(1)H coupling and only correlated to the heteronuclear coupling evolution. Consequently, an accurate (1)J(CH) can be measured even in the presence of strong coupling. We tested this method on N-acetyl-glucosamine and mannose whose apparent isotropic (1)J(CH) values are significantly affected by strong coupling with other methods. Agreement to within 0.5Hz or better is found between (1)J(CH) measured by this method and previously published simulation data. We further examined the strong coupling effects on RDC measurements and observed an error up to 100% for one bond RDCs using coupled HSQC in carbohydrates. We demonstrate that RDCs can be obtained with higher accuracy by CTi-CT-HSQC, which compensates the limitation of simulation method. PMID:23294631
Constant time INEPT CT-HSQC (CTi-CT-HSQC) - A new NMR method to measure accurate one-bond J and RDCs with strong 1H-1H couplings in natural abundance
NASA Astrophysics Data System (ADS)
Yu, Bingwu; van Ingen, Hugo; Freedberg, Dar¾n I.
Strong 1H-1H coupling can significantly reduce the accuracy of 1JCH measured from frequency differences in coupled HSQC spectra. Although accurate 1JCH values can be extracted from spectral simulation, it would be more convenient if the same accurate 1JCH values can be obtained experimentally. Furthermore, simulations reach their limit for residual dipolar coupling (RDC) measurement, as many significant, but immeasurable RDCs are introduced into the spin system when a molecule is weakly aligned, thus it is impossible to have a model spin system that truly represents the real spin system. Here we report a new J modulated method, constant-time INEPT CT-HSQC (CTi-CT-HSQC), to accurately measure one-bond scalar coupling constant and RDCs without strong coupling interference. In this method, changing the spacing between the two 180░ pulses during a constant time INEPT period selectively modulates heteronuclear coupling in quantitative J fashion. Since the INEPT delays for measuring one-bond carbon-proton spectra are short compared to 3JHH, evolution due to (strong) 1H-1H coupling is marginal. The resulting curve shape is practically independent of 1H-1H coupling and only correlated to the heteronuclear coupling evolution. Consequently, an accurate 1JCH can be measured even in the presence of strong coupling. We tested this method on N-acetyl-glucosamine and mannose whose apparent isotropic 1JCH values are significantly affected by strong coupling with other methods. Agreement to within 0.5 Hz or better is found between 1JCH measured by this method and previously published simulation data. We further examined the strong coupling effects on RDC measurements and observed an error up to 100% for one bond RDCs using coupled HSQC in carbohydrates. We demonstrate that RDCs can be obtained with higher accuracy by CTi-CT-HSQC, which compensates the limitation of simulation method.
Primary and secondary biomass burning aerosols determined by proton nuclear magnetic resonance (H-NMR) spectroscopy during the 2008 EUCAARI campaign in the Po Valley (Italy)
NASA Astrophysics Data System (ADS)
Paglione, M.; Saarikoski, S.; Carbone, S.; Hillamo, R.; Facchini, M. C.; Finessi, E.; Giulianelli, L.; Carbone, C.; Fuzzi, S.; Moretti, F.; Tagliavini, E.; Swietlicki, E.; Eriksson Stenstr÷m, K.; Prķv¶t, A. S. H.; Massoli, P.; Canaragatna, M.; Worsnop, D.; Decesari, S.
Atmospheric organic aerosols are generally classified into primary and secondary (POA and SOA) according to their formation processes. An actual separation, however, is challenging when the timescales of emission and of gas-to-particle formation overlap. The presence of SOA formation in biomass burning plumes leads to scientific questions about whether the oxidized fraction of biomass burning aerosol is rather of secondary or primary origin, as some studies would suggest, and about the chemical compositions of oxidized biomass burning POA and SOA. In this study, we apply nuclear magnetic resonance (NMR) spectroscopy to investigate the functional group composition of fresh and aged biomass burning aerosols during an intensive field campaign in the Po Valley, Italy. The campaign was part of the EUCAARI project and was held at the rural station of San Pietro Capofiume in spring 2008. Factor analysis applied to the set of NMR spectra was used to apportion the wood burning contribution and other organic carbon (OC) source contributions, including aliphatic amines. Our NMR results, referred to the polar, water-soluble fraction of OC, show that fresh wood burning particles are composed of polyols and aromatic compounds, with a sharp resemblance with wood burning POA produced in wood stoves, while aged samples are clearly depleted of alcohols and are enriched in aliphatic acids with a smaller contribution of aromatic compounds. The comparison with biomass burning organic aerosols (BBOA) determined by high resolution aerosol mass spectrometry (HR-TOF-AMS) at the site shows only a partial overlap between NMR BB-POA and AMS BBOA, which can be explained by either the inability of BBOA to capture all BB-POA composition, especially the alcohol fraction, or the fact that BBOA account for insoluble organic compounds unmeasured by the NMR. Therefore, an unambiguous composition for biomass burning POA could not be derived from this study, with NMR analysis indicating a higher O / C ratio compared to that measured for AMS BBOA. The comparison between the two techniques substantially improves when adding factors tracing possible contributions from biomass burning SOA, showing that the operational definitions of biomass burning organic aerosols are more consistent between techniques when including more factors tracing chemical classes over a range of oxidation levels. Overall, the non-fossil total carbon fraction was 50-57%, depending on the assumptions on the 14C content of non-fossil carbon, and the fraction of organic carbon estimated to be oxidized organic aerosol (OOA) from HR-TOF-AMS measurements was 73-100% modern.
Primary and secondary biomass burning aerosols determined by proton nuclear magnetic resonance (1H-NMR) spectroscopy during the 2008 EUCAARI campaign in the Po Valley (Italy)
NASA Astrophysics Data System (ADS)
Paglione, M.; Saarikoski, S.; Carbone, S.; Hillamo, R.; Facchini, M. C.; Finessi, E.; Giulianelli, L.; Carbone, C.; Fuzzi, S.; Moretti, F.; Tagliavini, E.; Swietlicki, E.; Eriksson Stenstr÷m, K.; Prķv¶t, A. S. H.; Massoli, P.; Canaragatna, M.; Worsnop, D.; Decesari, S.
Atmospheric organic aerosols are generally classified as primary and secondary (POA and SOA) according to their formation processes. An actual separation, however, is challenging when the timescales of emission and gas-to-particle formation overlap. The presence of SOA formation in biomass burning plumes leads to scientific questions about whether the oxidized fraction of biomass burning aerosol is rather of secondary or primary origin, as some studies would suggest, and about the chemical compositions of oxidized biomass burning POA and SOA. In this study, we apply nuclear magnetic resonance (NMR) spectroscopy to investigate the functional group composition of fresh and aged biomass burning aerosols during an intensive field campaign in the Po Valley, Italy. The campaign was part of the EUCAARI project and was held at the rural station of San Pietro Capofiume in spring 2008. Factor analysis applied to the set of NMR spectra was used to apportion the wood burning contribution and other organic carbon (OC) source contributions, including aliphatic amines. Our NMR results, referred to the polar, water-soluble fraction of OC, show that fresh wood burning particles are composed of polyols and aromatic compounds, with a sharp resemblance to wood burning POA produced in wood stoves, while aged samples are clearly depleted of alcohols and are enriched in aliphatic acids with a smaller contribution of aromatic compounds. The comparison with biomass burning organic aerosols (BBOA) determined by high-resolution aerosol mass spectrometry (HR-TOF-AMS) at the site shows only a partial overlap between NMR BB-POA and AMS BBOA, which can be explained by either the inability of BBOA to capture all BB-POA composition, especially the alcohol fraction, or the fact that BBOA account for insoluble organic compounds unmeasured by the NMR. Therefore, an unambiguous composition for biomass burning POA could not be derived from this study, with NMR analysis indicating a higher O / C ratio compared to that measured for AMS BBOA. The comparison between the two techniques substantially improves when adding factors tracing possible contributions from biomass burning SOA, showing that the operational definitions of biomass burning organic aerosols are more consistent between techniques when including more factors tracing chemical classes over a range of oxidation levels. Overall, the non-fossil total carbon fraction was 50-57%, depending on the assumptions about the 14C content of non-fossil carbon, and the fraction of organic carbon estimated to be oxidized organic aerosol (OOA) from HR-TOF-AMS measurements was 73-100% modern.
New insights on the structure of algaenan from Botryoccocus braunii race A and its hexane insoluble botryals based on multidimensional NMR spectroscopy and electrospray-mass spectrometry techniques.
Simpson, Andre J; Zang, Xu; Kramer, Robert; Hatcher, Patrick G
Through solution state NMR spectroscopy and quadrupole-time-of-flight mass spectrometry (Q-TOF MS) studies of the hexane insoluble botryal extract of the algae Botryococcus braunii race A, coupled with high-resolution magic-angle-spinning (HR-MAS) NMR spectroscopy of the algaenan from this alga, it has been possible to advance the structural understanding of this geochemically important biopolymer. It was found that the hexane insoluble botryals in this study constitute a mixture of low molecular weight unsaturated aliphatic aldehydes and unsaturated hydrocarbons with an average chain length of about 40 carbons. Exact assignments were provided for many of the structural units present and describe the average constitution of the mixture as a whole. Reticulation of the low molecular weight chains via acetal and ester links explains the primary make up of algaenan. In this study, it is concluded that the algaenan results from the reticulation of low molecular weight hexane insoluble botryal species rather than the polyaldehyde as previously observed in studies of algae at alternate stages of their growth cycle. PMID:12620332
The assessment of the quality of the graft in an animal model for lung transplantation using the metabolomics 1H high-resolution magic angle spinning NMR spectroscopy.
Benahmed, Malika A; Santelmo, Nicola; Elbayed, Karim; Frossard, Nelly; Noll, Eric; Canuet, Mathieu; Pottecher, Julien; Diemunsch, Pierre; Piotto, Martial; Massard, Gilbert; Namer, Izzie J
Standards are needed to control the quality of the lungs from nonheart-beating donors as potential grafts. This was here assessed using the metabolomics 1H high-resolution magic angle spinning NMR spectroscopy. Selective perfusion of the porcine bilung block was set up 30 min after cardiac arrest with cold Perfadex«. Lung alterations were analyzed at 3, 6, and 8 h of cold ischemia as compared to baseline and to nonperfused lung. Metabolomics analysis of lung biopsies allowed identification of 35 metabolites. Levels of the majority of the metabolites increased over time at 4░C without perfusion, indicating cellular degradation, whereas levels of glutathione decreased. When lung was perfused at 4░C, levels of the majority of the metabolites remained stable, including levels of glutathione. Levels of uracil by contrast showed a reverse profile, as its signal increased over time in the absence of perfusion while being totally absent in perfused samples. Our results showed glutathione and uracil as potential biomarkers for the quality of the lung. The metabolomics 1H high-resolution magic angle spinning NMR spectroscopy can be efficiently applied for the assessment of the quality of the lung as an original technique characterized by a rapid assessment of intact biopsy samples without extraction and can be implemented in hospital environment. PMID:22161974
Natural deuterium distribution in fatty acids isolated from peanut seed oil: a site-specific study by quantitative 2H NMR spectroscopy.
Duan, Jia-Rong; Billault, Isabelle; Mabon, Franńoise; Robins, Richard
Quantitative (2)H NMR spectroscopy has been used to measure the distribution of deuterium at natural abundance in long-chain fatty acids extracted from the same vegetable oil. Peanut seed oil was selected, due to its suitable oleic and linoleic acid content. The methyl esters of the fatty acids were prepared by transesterification and isolated by modified argentation column chromatography on silica. In order to measure the natural isotopic fractionation of deuterium (D) at the maximum number of positions, the purified methyl oleate and methyl linoleate were chemically cleaved and the (D/H)(i) values determined by quantitative (2)H NMR spectroscopy. It was thus possible to demonstrate that fractionation in deuterium occurs during the desaturation of oleate to linoleate. Furthermore, the previously observed distribution of deuterium at the sites of desaturation is confirmed, as is the alternating pattern of (D/H)(i), which relates to the origin of the pertinent hydrogen atoms. The data obtained are discussed in terms of the kinetic isotopic effects intrinsic to the enzymes-synthetases and desaturases-involved in the biosynthesis of fatty acids. PMID:12203973
Solution structure of the 45-residue MgATP-binding peptide of adenylate kinase as examined by 2-D NMR, FTIR, and CD spectroscopy
Fry, D.C.; Byler, D.M.; Susi, H.; Brown, M.; Kuby, S.A.; Mildvan A.S.
The structure of a synthetic peptide corresponding to residues 1-45 of rabbit muscle adenylate kinase has been studied in aqueous solution by two-dimensional NMR, FTIR, and CD spectroscopy. This peptide, which binds MgATP and is believed to represent most of the MgATP-binding site of the enzyme, appears to maintain a conformation similar to that of residues 1-45 in the X-ray structure of intact porcine adenylate kinase, with 42% of the residues of the peptide showing NOEs indicative of phi and psi angles corresponding to those found in the protein. The NMR studies suggest that the peptide is composed of two helical regions of residues 4-7 and 23-29, and three stretches of ..beta..-strand at residues 8-15, 30-32, and 35-40, yielding an overall secondary structure consisting of 24% ..cap alpha..-helix, 38% ..beta..-structure, and 38% aperiodic. Although the resolution-enhanced amide I band of the peptide FTIR spectrum is broad and rather featureless, possible due to disorder, it can be fit by using methods developed on well-characterized globular proteins. The CD spectrum is best fit by assuming the presence of at most 13% ..cap alpha..-helix in the peptide, 24 +/- 2% ..beta..-structure, and 66 +/- 4% aperiodic. The inability of the high-frequency FTIR and CD methods to detect helices in the amount found by NMR may result from the short helical lengths as well as from static and dynamic disorder in the peptide. Upon binding of MgATP, numerous conformation changes in the backbone of the peptide are detected by NMR, with smaller alterations in the overall secondary structure as assess by CD.
Evidence for a dipolar-coupled AM system in carnosine in human calf muscle from in vivo 1H NMR spectroscopy
NASA Astrophysics Data System (ADS)
Schr÷der, Leif; Bachert, Peter
Spin systems with residual dipolar couplings such as creatine, taurine, and lactate in skeletal muscle tissue exhibit first-order spectra in in vivo 1H NMR spectroscopy at 1.5 T because the coupled protons are represented by (nearly) symmetrized eigenfunctions. The imidazole ring protons (H2, H4) of carnosine are suspected to form also a coupled system. The ring's stiffness could enable a connectivity between these anisochronous protons with the consequence of second-order spectra at low field strength. Our purpose was to study whether this deviation from the Paschen-Back condition can be used to detect the H2-H4 coupling in localized 1D 1H NMR spectra obtained at 1.5 T (64 MHz) from the human calf in a conventional whole-body scanner. As for the hydrogen hyperfine interaction, a Breit-Rabi equation was derived to describe the transition from Zeeman to Paschen-Back regime for two dipolar-coupled protons. The ratio of the measurable coupling strength ( Sk) and the difference in resonance frequencies of the coupled spins (? ?) induces quantum-state mixing of various degree upon definition of an appropriate eigenbase of the coupled spin system. The corresponding Clebsch-Gordan coefficients manifest in characteristic energy corrections in the Breit-Rabi formula. These additional terms were used to define an asymmetry parameter of the line positions as a function of Sk and ? ?. The observed frequency shifts of the resonances were found to be consistent with this parameter within the accuracy achievable in in vivo NMR spectroscopy. Thus it was possible to identify the origin of satellite peaks of H2, H4 and to describe this so far not investigated type of residual dipolar coupling in vivo.
[Application of 2d NMR techniques in the structure determination of ganosporelactone A and B].
Chen, R Y; Yu, D Q
Structure and stereochemistry of ganosporelactone A and B isolated from the spores of Ganoderma lucidum have been elucidated by the use of 1H-1H COSY, 1H-13C COSY, 1H-13C COLOC and NOESY 2D NMR spectroscopy. Ganosporelactone A and B are two novel pentacyclic triterpenoids which may be biogenetically derived from lanostane skeleton through the construction of C16 and C23 bond. PMID:1789109
{sup 1}H NMR-based spectroscopy detects metabolic alterations in serum of patients with early-stage ulcerative colitis
Zhang, Ying; Lin, Lianjie [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China)] [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China); Xu, Yanbin [Wanlei Life Sciences (Shenyang) Co., Ltd., Shenyang 110179 (China)] [Wanlei Life Sciences (Shenyang) Co., Ltd., Shenyang 110179 (China); Lin, Yan; Jin, Yu [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China)] [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China); Zheng, Changqing, E-mail: email@example.com [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China)] [Second Department of Gastroenterology, Shengjing Hospital, China Medical University, Shenyang 110004 (China)
Highlights: ĢTwenty ulcerative colitis patients and nineteen healthy controls were enrolled. ĢIncreased 3-hydroxybutyrate, glucose, phenylalanine, and decreased lipid were found. ĢWe report early stage diagnosis of ulcerative colitis using NMR-based metabolomics. -- Abstract: Ulcerative colitis (UC) has seriously impaired the health of citizens. Accurate diagnosis of UC at an early stage is crucial to improve the efficiency of treatment and prognosis. In this study, proton nuclear magnetic resonance ({sup 1}H NMR)-based metabolomic analysis was performed on serum samples collected from active UC patients (n = 20) and healthy controls (n = 19), respectively. The obtained spectral profiles were subjected to multivariate data analysis. Our results showed that consistent metabolic alterations were present between the two groups. Compared to healthy controls, UC patients displayed increased 3-hydroxybutyrate, ?-glucose, ?-glucose, and phenylalanine, but decreased lipid in serum. These findings highlight the possibilities of NMR-based metabolomics as a non-invasive diagnostic tool for UC.
Analysis of organic matter at the soil-water interface by NMR spectroscopy: Implications for contaminant sorption processes
NASA Astrophysics Data System (ADS)
Simpson, M. J.; Simpson, A. J.
Contaminant sorption to soil organic matter (OM) is the main fate of nonionic, hydrophobic organic contaminants in terrestrial environments and a number of studies have suggested that both soil OM structure and physical conformation (as regulated by the clay mineral phase) govern contaminant sorption processes. A great deal of this evidence has come from macroscopic observations with contaminants and soil fractions as well as a recent mass balance approach where the sum of the parts exceeded the whole suggesting that the physical arrangement of OM in organo-mineral complexes may be more important than OM structure in sorption processes (1). In addition, recent studies with constructed organo-mineral complexes have suggested that aliphatic OM is preferred over aromatic moieties and suggests that clay minerals play an indirect role by governing the sorption of organic contaminants by controlling the surface accessibility of OM at the soil-water interface (2,3). To investigate this further, a number of soil samples were characterized by both solid-state 13C Cross Polarization Magic Angle Spinning (CPMAS) NMR and 1H High Resolution Magic Angle Spinning (HR-MAS) NMR. HR-MAS NMR is an innovative NMR method that allows one to examine samples that are semi-solid using liquid state NMR methods (ie: observe 1H which is more sensitive than 13C). With HR-MAS NMR, only those structures that are in contact with the solvent are NMR visible thus one can probe different components within a mixture using different solvents. The 1H HR-MAS NMR spectrum of a grassland soil swollen in water (D2O) is dominated by signals from alkyl and O-alkyl structures but signals from aromatic protons are negligible (the peak at ~8.2ppm is attributed to formic acid). When the soil is swollen in DMSO-d6, a solvent which is more penetrating and capable of breaking hydrogen bonds, aromatic signals are visible suggesting that the aromatic structures are buried within the soil matrix and do not exist at the soil-water interface. The 13C solid-state NMR data confirms that aromatic carbon is present in substantial amounts (estimated at ~40% of the total 13C signal) therefore, the lack of 1H aromatic signals in the HR-MAS NMR spectrum indicates that aromatic structures are buried and that the soil-water interface is dominated by aliphatic chains, carbohydrates, and peptides. The NMR data indicates that the mineral component of soils governs the physical conformation of OM at the soil-water interface. Consequently, one must consider that one-dimensional NMR methods provide an excellent overview of all the structures that are present but they do not provide direct information regarding which structures are available or accessible at the soil-water interface for contaminant interactions. References: (1) Bonin J.L. and Simpson M.J. 2007 Environmental Science & Technology 41:153-159. (2) Feng X., Simpson A.J., and Simpson M.J. 2006. Environmental Science & Technology 40:3260- 3266. (3) Simpson A.J. et al. 2006. Langmuir 22:4498-4503.
Interactions of Interleukin-8 with the Human Chemokine Receptor CXCR1 in Phospholipid Bilayers by NMR Spectroscopy
Park, Sang Ho; Casagrande, Fabio; Cho, Leah; Albrecht, Lauren; Opella, Stanley J.
CXCR1 is a receptor for the chemokine interleukin-8 (IL-8), a mediator of immune and inflammatory responses. Strategically located in the cell membrane, CXCR1 binds to IL-8 with high affinity, and subsequently transduces a signal across the membrane bilayer to a G-protein activated second messenger system. Here we describe NMR studies of the interactions between IL-8 and human CXCR1 in lipid environments. Functional full-length and truncated constructs of CXCR1 and full-length IL-8 were uniformly 15N-labeled by expression in bacteria followed by purification and refolding. The residues responsible for interactions between IL-8 and the N-terminal domain of CXCR1 were identified by specific chemical shift perturbations of assigned resonances on both IL-8 and CXCR1. Solution NMR signals from IL-8 in q=0.1 isotropic bicelles disappeared completely when CXCR1 in lipid bilayers was added in a 1:1 molar ratio, indicating that binding to the receptor-containing bilayers immobilizes IL-8 (on the ~105 Hz timescale) and broadens the signals beyond detection. The same solution NMR signals from IL-8 were less affected by the addition of N-terminal truncated CXCR1 in lipid bilayers, demonstrating that the N-terminal domain of CXCR1 is mainly responsible for binding to IL-8. The interaction is tight enough to immobilize IL-8 along with the receptor in phospholipid bilayers, and is specific enough to result in well-aligned samples in oriented sample solid-state NMR spectra. A combination of solution NMR and solid-state NMR studies of IL-8 in the presence of various constructs of CXCR1 enable us to propose a model for a multi-step binding process. PMID:22019593
1H and 13C resonance designation of antimycin A1 by two-dimensional NMR spectroscopy
Abidi, S.L.; Adams, B.R.
Complete 1H and 13C resonance assignments of antimycin A1 were accomplished by two-dimensional NMR techniques, viz. 1H homonuclear COSY correlation, heteronuclear 13C-1H chemical shift correlation and long-range heteronuclear 13C-1H COLOC correlation. Antimycin A1 was found to consist of two isomeric components in a 2:1 ratio based on NMR spectroscopic evidence. The structure of the major component was newly assigned as the 8-isopentanoic acid ester. The spectra of the minor component were consistent with the known structure of antimycin A1.
Polymer swelling, drug mobilization and drug recrystallization in hydrating solid dispersion tablets studied by multinuclear NMR microimaging and spectroscopy.
Dahlberg, Carina; Dvinskikh, Sergey V; Schuleit, Michael; Fur¾, Istvßn
Despite the advantages offered by solid dispersions, the marketed products based on this technology are few. The most frequent concern is the stability of the amorphous drug. The state of the drug in solid dispersions is, in general, poorly characterized as the number of characterization techniques available to monitor nanometer-sized drug particles embedded in a matrix are limited. Here we present a combination of localized NMR spectroscopic and NMR imaging techniques which allow in situ monitoring of the state of the drug during tablet disintegration and dissolution. (19)F NMR relaxation is shown to be sensitive to both the crystalline/amorphous state and the size of the model nanoparticles made of the drug substance flutamide. The time course of drug mobilization and recrystallization is detected with spatial resolution within swelling solid dispersion tablets. Comparing results from spatially resolved (19)F, (2)H and (1)H NMR experiments, recrystallization is related to its enabling factors such as local hydration level and local mobility of the polymer matrix. The initially amorphous drug may recrystallize either by nanoparticle coalescence or by ripening of crystalline grains. PMID:21696185
Cerebral glucose metabolism and the glutamine cycle as detected by in vivo and in vitro 13 C NMR spectroscopy
Mar??a A Garc??a-Espinosa; Tiago B Rodrigues; Alejandra Sierra; Marina Benito; Carla Fonseca; Heather L Gray; Brenda L Bartnik; Mar??a L Garc??a-Mart??n; Paloma Ballesteros; Sebastißn Cerdßn
We review briefly 13C NMR studies of cerebral glucose metabolism with an emphasis on the roles of glial energetics and the glutamine cycle. Mathematical modeling analysis of in vivo 13C turnover experiments from the C4 carbons of glutamate and glutamine are consistent with: (i) the glutamine cycle being the major cerebral metabolic route supporting glutamatergic neurotransmission, (ii) glial glutamine synthesis
Chemical Characterization and Water Content Determination of Bio-Oils Obtained from Various Biomass Species using 31P NMR Spectroscopy
David, K.; Ben, H.; Muzzy, J.; Feik, C.; Iisa, K.; Ragauskas, A.
Pyrolysis is a promising approach to utilize biomass for biofuels. One of the key challenges for this conversion is how to analyze complicated components in the pyrolysis oils. Water contents of pyrolysis oils are normally analyzed by Karl Fischer titration. The use of 2-chloro-4,4,5,5,-tetramethyl-1,3,2-dioxaphospholane followed by {sup 31}P NMR analysis has been used to quantitatively analyze the structure of hydroxyl groups in lignin and whole biomass. Results: {sup 31}P NMR analysis of pyrolysis oils is a novel technique to simultaneously characterize components and analyze water contents in pyrolysis oils produced from various biomasses. The water contents of various pyrolysis oils range from 16 to 40 wt%. The pyrolysis oils obtained from Loblolly pine had higher guaiacyl content, while that from oak had a higher syringyl content. Conclusion: The comparison with Karl Fischer titration shows that {sup 31}P NMR could also reliably be used to measure the water content of pyrolysis oils. Simultaneously with analysis of water content, quantitative characterization of hydroxyl groups, including aliphatic, C-5 substituted/syringyl, guaiacyl, p-hydroxyl phenyl and carboxylic hydroxyl groups, could also be provided by {sup 31}P NMR analysis.
Distribution of polyphosphates in cell-compartments of Chlorella fusca as measured by 31 P-NMR-spectroscopy
J. Sianoudis; A. C. Kiisel; A. Mayer; L. H. Grimme; D. Leibfritz
In suspensions of the green alga Chlorella fusca the influence of high pH and high ethylene-diamine-tetraacetic acid concentrations in the external medium, of French-press and perchloric acid extraction of the cells and of alkalization of the intracellular pH on the polyphosphate signal in 31P-nuclear magnetic resonance (31P NMR) spectra was investigated.
Cytochrome c552 Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy
Fayer, Michael D.
Cytochrome c552 Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR cofactor in two mutated forms of the cytochrome c552 from Hydrogenobacter thermophilus. The first mutant in the presence of a hydrogen bond donor. I. Introduction Cytochromes c (cyt c's) are small electron-transfer heme
NMR IN BIOMEDICINE NMR Biomed. in press
Loening, Niko
. Copyright # 2005 John Wiley & Sons, Ltd. KEYWORDS: 31 P edited 1 H NMR; INEPT; choline compounds; human.interscience.wiley.com). DOI:10.1002/nbm.973 Quantification of phosphocholine and glycerophosphocholine with 31 P edited 1 H. Here, a new scheme that uses 31 P edited 1 H spectroscopy to quantify the concentrations of choline, PC
NSDL National Science Digital Library
Hornak, Joseph P.
Dr. Joseph Hornak of the Rochester Institute of Technology presents this high quality hypertextbook for in-depth coverage of the physics and technique behind Nuclear Magnetic Resonance (NMR) (For Dr. Hornak's Basics of MRI, see the August 4, 1999 Scout Report for Science & Engineering). The material is presented in a detailed and clear manner without over simplifying the concepts. Chapters include "The Mathematics of NMR," "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Pulse Sequences," and much more. A chapter on "NMR Hardware" offers an overview of components (like the superconducting magnet and various coils) used in most NMR systems. The "Practical Considerations" chapter emphasizes spectroscopic techniques. With the screen split into two separate frames, explanatory graphics can be viewed alongside the text. A glossary and a list of symbols are also included in this carefully produced textbook.
Normal coordinate analysis, molecular structure, vibrational, electronic spectra and NMR investigation of 4-Amino-3-phenyl-1H-1,2,4-triazole-5(4H)-thione by ab initio HF and DFT method
NASA Astrophysics Data System (ADS)
Bahgat, Khaled; Fraihat, Safwan
In the present work, the characterization of 4-Amino-3-phenyl-1H-1,2,4-triazole-5(4H)-thione (APTT) molecule was carried out by quantum chemical method and vibrational spectral techniques. The FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra of APTT were recorded in solid phase. The UV-Vis absorption spectrum of the APTT was recorded in the range of 200-400 nm. The molecular geometry, harmonic vibrational frequencies and bonding features of APTT in the ground state have been calculated by HF and DFT methods using 6-311++G(d,p) basis set. The complete vibrational frequency assignments were made by normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The molecular stability and bond strength were investigated by applying the natural bond orbital analysis (NBO) and natural localized molecular orbital (NLMO) analysis. The electronic properties, such as excitation energies, absorption wavelength, HOMO and LUMO energies were performed by time depended DFT (TD-DFT) approach. The 1H and 13C nuclear magnetic resonance chemical shift of the molecule were calculated using the gauge-including atomic orbital (GIAO) method and compared with experimental results. Finally, the calculation results were analyzed to simulate infrared, FT-Raman and UV spectra of the title compound which shows better agreement with observed spectra.
Study of the chromonic liquid-crystalline phases of bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride by polarized optical microscopy and 2H NMR spectroscopy.
Tam-Chang, Suk-Wah; Iverson, Isaac K; Helbley, Jennifer
The chromonic liquid-crystalline properties of bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride in an aqueous solution were investigated by polarized light microscopy and 2H NMR spectroscopy. Both techniques indicate a narrow I + N biphasic region and a broad N phase region at concentrations ranging from approximately 6.9 to approximately 30 wt % at room temperature. Optical microscopy indicates that a hexagonal M phase exists at higher concentrations. The variation of the I --> N + I and N + I --> N transition temperatures with concentration was studied by 2H NMR spectroscopy. Finally, the effects of temperature and concentration on the order parameter of the N phase were investigated by 2H NMR using a tetra-deuterated derivative. A value of 0.97 was obtained for the N phase at its upper concentration limit. PMID:15743076
Study by │╣P NMR spectroscopy of the triacylglycerol degradation processes in olive oil with different heat-transfer mechanisms.
Lucas-Torres, Covadonga; Pķrez, Angel; Caba±as, Beatriz; Moreno, Andrķs
The thermal degradation of olive oil using conventional and microwave heating under the same experimental conditions were compared. A powerful identification and quantification technique based on (31)P NMR has been developed to characterise the differences between the minor components including diacylglycerol and free fatty acids in the heated samples. The (31)P NMR spectra of the degraded olive oils, which contain OH groups derivatised with a phosphorus reagent, showed that conventional heating is more detrimental to the oil than microwave technique. Conventional heating leads to a significant increase in the diacylglycerol and free fatty acid contents as well as in the number of degradation compounds, which damage the olive oil quality. However, the main process that takes place on using microwave heating is isomerisation between diacylglycerols, a change that could give a potential longer shelf life to the olive oil. PMID:25038644
Investigating the interaction between peptides of the amphipathic helix of Hcf106 and the phospholipid bilayer by solid-state NMR spectroscopy
Zhang, Lei; Liu, Lishan; Maltsev, Sergey; Lorigan, Gary A.; Dabney-Smith, Carole
The chloroplast twin arginine translocation (cpTat) system transports highly folded precursor proteins into the thylakoid lumen using the protonmotive force as its only energy source. Hcf106, as one of the core components of the cpTat system, is part of the precursor receptor complex and functions in the initial precursor-binding step. Hcf106 is predicted to contain a single amino terminal transmembrane domain followed by a Pro-Gly hinge, a predicted amphipathic ?-helix (APH), and a loosely structured carboxy terminus. Hcf106 has been shown biochemically to insert spontaneously into thylakoid membranes. To better understand the membrane active capabilities of Hcf106, we used solid-state NMR spectroscopy to investigate those properties of the APH. In this study, synthesized peptides of the predicted Hcf106 APH (amino acids 28¢65) were incorporated at increasing mol% into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) and POPC/MGDG (monogalactosyldiacylglycerol; mole ratio 85:15) multilamellar vesicles (MLVs) to probe the peptide-lipid interaction. Solid-state 31P NMR and 2H NMR spectroscopic experiments revealed that the peptide perturbs the headgroup and the acyl chain regions of phospholipids as indicated by changes in spectral lineshape, chemical shift anisotropy (CSA) line width, and 2H order SCD parameters. In addition, the comparison between POPC MLVs and POPC/MGDG MLVs indicated that the lipid bilayer composition affected peptide perturbation of the lipids, and such perturbation appeared to be more intense in a system more closely mimicking a thylakoid membrane. PMID:24144541
Investigating the interaction between peptides of the amphipathic helix of Hcf106 and the phospholipid bilayer by solid-state NMR spectroscopy.
Zhang, Lei; Liu, Lishan; Maltsev, Sergey; Lorigan, Gary A; Dabney-Smith, Carole
The chloroplast twin arginine translocation (cpTat) system transports highly folded precursor proteins into the thylakoid lumen using the protonmotive force as its only energy source. Hcf106, as one of the core components of the cpTat system, is part of the precursor receptor complex and functions in the initial precursor-binding step. Hcf106 is predicted to contain a single amino terminal transmembrane domain followed by a Pro-Gly hinge, a predicted amphipathic ?-helix (APH), and a loosely structured carboxy terminus. Hcf106 has been shown biochemically to insert spontaneously into thylakoid membranes. To better understand the membrane active capabilities of Hcf106, we used solid-state NMR spectroscopy to investigate those properties of the APH. In this study, synthesized peptides of the predicted Hcf106 APH (amino acids 28-65) were incorporated at increasing mol.% into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) and POPC/MGDG (monogalactosyldiacylglycerol; mole ratio 85:15) multilamellar vesicles (MLVs) to probe the peptide-lipid interaction. Solid-state (31)P NMR and (2)H NMR spectroscopic experiments revealed that the peptide perturbs the headgroup and the acyl chain regions of phospholipids as indicated by changes in spectral lineshape, chemical shift anisotropy (CSA) line width, and (2)H order SCD parameters. In addition, the comparison between POPC MLVs and POPC/MGDG MLVs indicated that the lipid bilayer composition affected peptide perturbation of the lipids, and such perturbation appeared to be more intense in a system more closely mimicking a thylakoid membrane. PMID:24144541
Refinement of borate structures from 11B MAS NMR spectroscopy and density functional theory calculations of 11B electric field gradients.
Hansen, Michael Ryan; Madsen, Georg K H; Jakobsen, Hans J; Skibsted, J°rgen
The refinement of borate structures using DFT calculations combined with experimental (11)B quadrupole coupling parameters from solid-state NMR spectroscopy is presented. The (11)B electric field gradient (EFG) tensors, calculated using the WIEN2k software for trigonal and tetrahedral boron sites in a series of model compounds, exhibit a convincing linear correlation with the quadrupole coupling tensor elements, determined from (11)B MAS NMR spectra of the central or satellite transitions. The model compounds include Li(2)B(4)O(7), Mg(2)B(2)O(5), Mg(3)B(2)O(6), NH(4)B(C(6)H(5))(4), and colemanite (CaB(3)O(4)(OH)(3).H(2)O). The (11)B quadrupole moment, Q = 0.0409 +/- 0.0002 barn, derived from the linear correlation, is in excellent agreement with the accepted value for Q((11)B). This demonstrates that DFT (WIEN2k) calculations can provide precise (11)B quadrupole coupling parameters on an absolute scale. On the other hand, DFT calculations based on the reported crystal structures for datolite (CaBSiO(4)(OH)) and danburite (CaB(2)Si(2)O(8)) cannot reproduce the experimental (11)B quadrupole coupling parameters to the same high precision. However, optimization of these structures by minimization of the forces between the atoms (obtained by DFT) results in a significant improvement between the calculated and experimental (11)B quadrupole coupling parameters, which indicates that reliable refinements of the borate structures are obtained by this method. Finally, the DFT calculations also provide important structural information about the sign and orientation of the EFG tensor elements in the crystal frame, a kind of information that cannot be achieved from (11)B NMR experiments on powdered samples. PMID:16833533
FT-IR, FT-Raman, UV-Visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol
NASA Astrophysics Data System (ADS)
Chain, Fernando E.; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandßn, Silvia A.
In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G? basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated 1H NMR and 13C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations.
FT-IR, FT-Raman, UV-visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol.
Chain, Fernando E; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandßn, Silvia A
In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G(?) basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated (1)H NMR and (13)C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations. PMID:25498827
Characterization of sacha inchi ( Plukenetia volubilis L.) oil by FTIR spectroscopy and 1 H NMR. Comparison with linseed oil
MarĒa D. Guillķn; Ainhoa Ruiz; Nerea Cabo; Rosana Chirinos; Gloria Pascual
Three oil samples obtained from sacha inchi (Plukenetia volubilis L.) seeds were studied by means of FTIR and 1H NMR. Frequency data of the most significant bands of the IR spectrum of this oil are given. These data show that sacha inchi\\u000a oil has a high degree of unsaturation. The same fact is deduced from the ratio between the absorbance
The structures of the active center in dark-adapted bacteriorhodopsin by solution-state NMR spectroscopy
Heiko Patzelt; Bernd Simon; Antonius Terlaak; Brigitte Kessler; Ronald K³hne; Peter Schmieder; Dieter Oesterhelt; Hartmut Oschkinat
The two forms of bacteriorhodopsin present in the dark-adapted state, containing either all-trans or 13-cis,15-syn retinal, were examined by using solution state NMR, and their structures were determined. Comparison of the all-trans and the 13-cis,15-syn forms shows a shift in position of about 0.25 ┼ within the pocket of the protein. Comparing this to the 13-cis,15-anti chromophore of the catalytic
Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy
Jacqueline R Houston; Robert S Maxwell; Susan A Carroll
Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline
A simple air system for temperature stabilization in the range -10 to +80 degrees C for use in NMR spectroscopy.
Anisimov, A V; Dautova, N R
This paper proposes a design for a system of temperature stabilization within the range from -10 to +80+/-0.5 degrees C for NMR spectrometers which is simple and affordable to fabricate in a laboratory. The design utilizes a closed system of circulation of an air heat carrier, twofold flow around the thermostabilized system, cooling element on Peltier thermal modules, and a proportional-integral-derivative regulator. PMID:20687753
1H NMR Spectroscopy Profiling of Metabolic Reprogramming of Chinese Hamster Ovary Cells upon a Temperature Shift during Culture
Povey, Jane F.; Smales, C. Mark; Howard, Mark J.
We report an NMR based approach to determine the metabolic reprogramming of Chinese hamster ovary cells upon a temperature shift during culture by investigating the extracellular cell culture media and intracellular metabolome of CHOK1 and CHO-S cells during culture and in response to cold-shock and subsequent recovery from hypothermic culturing. A total of 24 components were identified for CHOK1 and 29 components identified for CHO-S cell systems including the observation that CHO-S media contains 5.6 times the level of glucose of CHOK1 media at time zero. We confirm that an NMR metabolic approach provides quantitative analysis of components such as glucose and alanine with both cell lines responding in a similar manner and comparable to previously reported data. However, analysis of lactate confirms a differentiation between CHOK1 and CHO-S and that reprogramming of metabolism in response to temperature was cell line specific. The significance of our results is presented using principal component analysis (PCA) that confirms changes in metabolite profile in response to temperature and recovery. Ultimately, our approach demonstrates the capability of NMR providing real-time analysis to detect reprogramming of metabolism upon cellular perception of cold-shock/sub-physiological temperatures. This has the potential to allow manipulation of metabolites in culture supernatant to improve growth or productivity. PMID:24130854