Acid and Alkaline Degradation of the TNP-Amino Acids and -Peptides

• Published in: Journal of biochemistry (Tokyo) 1964-10, Vol.56 (4), p.299-307
• Main Authors: KOTAKI, AKIRA, SATAKE, KAZUO
• Format: Article
• Language: English
• Subjects: Amino Acids; Chemistry Techniques, Analytical; Chromatography; Hydrochloric Acid; Hydroxides; Insulin; NADP; Old Medline; Peptides; Picrates; Spectrum Analysis
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a127993

Most of TNP-amino acids could be hydrolyzed with N sodium hydroxide at room temperature and gave picric acid and the corresponding free amino acids quantitatively. However, TNP-glycine, -serine and -threonine were decomposed into unidentified colored substances, without producing an appreciable amount of picric acid and free amino acids. TNP-Amino acids were rather stable in acid. For example, no appreciable amount of TNP-valine was hydrolyzed with 6 N hydrochloric acid, and more than 80 per cent remained intact even with 12 N acid, after the treatment for 72 hours at 37°C. TNP-α-NH linkage of TNP-amino acids and -peptides, however, was cleaved quantitatively into picric acid and original free amino acids by heating with 6 N hydrochloric acid at 110°C or 8 to 10 hours. TNP-ω-NH linkages were rather resistant to the conditions, and more than 60 per cent were capable of remaining intact even after the prolonged heating for 24 hours in 6 N hydrochloric acid. Extreme stability of TNP-amines in acid was also observed. Analysis of TNP-peptides produced by the partial acid or enzymatic hydrolysis of TNP-protein was described. Amino acid contents of these TNP-peptides were able to be represented as the relative ratios to the contents of picric acid, liberated.