Ninhydrin test is used for -
Bile salts
Amino acids
Nucleic acid
Lipids
Ans. is 'b' i.e., Amino acids Important chemicai reactions of amino acidso Fol(owing are some important chemical reactions.Reaction used to determine amino acid sequence in polypeptide chain : -Generally, amino terminal (N-tenninal) of amino acid is tagged with some reagent. It is split offby hydrolysis and tagged amino acid is identified. The reaction is, then, repeated with new N-terminal of subsequent amino acid and so on. The two reactions are used for identification of amino acid sequence : -Sanger's reaction : - Uses Sanger's reagent (1 -fluoro-2,4-dinitrobenzene) to tag amino terminal.Edman's reaction : - Uses Edman's reagent (phenylisothiocyanate) to tag amino terminal.Reaction used to identification of individual or group of amino acids : - These reactions are frequently used for qualitative detection and quantitative measurement of various amino acids.Xin hydrin test0 : - All a-amino acids.Xanthophoretic reaction : - Aromatic amino acids Q (Tyrosine, try ptophan, phenylalanine).Millan's test Q (Miilon-Nasse reaction): - Tyrosine Q (phenol group of tyrosine). Therefore millon's test is positive in tyrosinosis Q.Aldehyde test: - Tryptophan (indole ring)Hopkins-cole reaction : - Tryptophan (indole ring)Sakaguch's reaction : - Arginine (guanidinium group of arginine).Sulphur test: - Cysteine (sulphydryl group)Nitroprusside test: - Cysteine (sulphydryl group)Pauly's test: - Histidine (imidazole group)Biuret reaction : - Peptide bondDiazo reaction Q (Pauli's) : - Histidine or tyrosine.
Amino Acids Basics