Which among the following when reacted with diazotized sulfanilic acid under alkaline conditions, a red color is formed?
Pauly's test: Pauly's test is used for detecting the presence of histidine in proteins. When proteins containing histidine react with diazotized sulfanilic acid under alkaline conditions, a red color is formed by a coupling reaction. The same reagent will give an orange colored product with the phenol group of tyrosine TEST/REACTION AMINO ACID Biuret Reaction Two peptide linkages Ninhydrin Reaction Alpha- amino acids Xanthoproteic Reaction Benzene ring of aromatic amino acids Millons Reaction Folin-Ciocalteu's Test Phenolic group (Tyrosine) Hopkins-Cole Reaction Indole ring (Tryptophan) Sakaguchi Reaction Guanidine group (Arginine) Nitroprusside Reaction Sulfur Test Sulfhydryl groups (Cysteine) Pauly's Test Imidazole ring (Histidine) Reference: Harpers illustrated biochemistry 30th edition
Tyrosine
Arginine
Histidine
Cysteine
General anatomy