Abstract

The apparent rate constants of the formation (k1) and hydrolysis (k2) of the Schiff bases formed by pyridoxal 5?-phosphate with L-tryptophan and their methyl and n-butyl esters at a variable pH, 25 °C, and an ionic strength of 0.1 M were determined, along with the equilibrium constant (KpH). The individual rate constants of formation and hydrolysis of the Schiff bases of systems corresponding to different chemical species present in the medium as a function of its acidity were also determined, as were the pK values for the Schiff bases. The influence of the ?-carboxyl group on the formation and hydrolysis constants of the Schiff bases, and also on their pK values, is demonstrated.