Abstract
Reactions of amino acids and related amines with pyridoxal in methanol were studied by the changes of electronic absorption spectra. Most amino acids and amines formed Schiff bases, which existed in keto-enamine and enol-imine forms. Equilibrium between the two tautomeric forms was affected by the nature of amino acids or amine residues. Amino acids having a secondary amino group formed carbinolamine derivatives with pyridoxal. Cysteine and cysteamine gave products which had thiazolidine rings, while histidine, and 5-substituted tryptophans formed tetrahydropyridine derivatives asultimate products. The spectral properties, solution equilibria in methanol and band assignments of the Schiff bases and other products formed were described.
