Kinetic aspects of regulation of pyruvic decarboxylase

The decarboxylation of pyruvate catalysed by pyruvic decarboxylase (EC 4.1.1.1) from wheat germ is shown to be autocatalytic. Evidence is presented which suggests that the enzyme exists in an active and an inactive form—the latter being converted into the active form in the presence of pyruvate and by low pH. It is suggested that the relatively slow interconversion of the two forms of the enzyme may represent a time buffering system to prevent the decarboxylation of pyruvate in response to transient changes in pH.