Dependence upon pH of Steady‐State Parameters for the β‐Galactosidase‐Catalysed Hydrolyses of β‐D‐Galactopyranosyl Derivatives of Different Chemical Types

Abstract

The effect of pH upon the .beta.-galactosidase[EC 3.2.1.23, from Escherichia coli]-catalyzed hydrolyzes of aryl galactosides is essentially similar for each of the 3 steps of their hydrolysis. It differs markedly from that on the hydrolysis of galactosyl pyridinium salts; these proceed through a non-bottleneck pathway. While pH increase abolishes the rate of every step of the reaction for aryl galactosides, it favors the 1st step of hydrolysis of the galactosyl pyridinium salts, which supports the hypothesis that catalysis of these compounds originates largely in non-covalent interactions.