{'fraction_non_alphanumeric': 0.024451939291736932, 'fraction_numerical': 0.010961214165261383, 'mean_word_length': 5.0561224489795915, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Spectroscopic Investigation on the Primary Photoreaction of Bathy Phytochrome Agp2-Pr of Agrobacterium fabrum: Isomerization in a pH-dependent H-bond Network.

Bathy phytochrome Agp2 from Agrobacterium fabrum exhibits an unusually low pKa =7.6 in the Pr state in contrast to a pKa >11 in the Pfr state, indicating a pH-dependent charge distribution and H-bond network in the Pr chromophore binding pocket around neutral pH. Here, we report on ultrafast UV/Vis absorption spectroscopy of the primary Pr photoisomerization of Agp2 at pH 6 and pH 9 and upon H2 O/D2 O buffer exchange. The triexponential Pr kinetics slows down at increased pH and pronounced pH-dependent kinetic isotope effects are observed. The results on the Pr photoreaction suggest: 1) component-wise hindered dynamics on the chromophore excited-state potential energy surface at high pH and 2) proton translocation processes either via single-proton transfer or via significant reorganization of H-bond networks. Both effects reflect the interplay between the pH-dependent charge distribution in the Pr chromophore binding pocket on the one hand and chromophore excitation and its Z→E isomerization on the other hand.