Inhibitors, activators and inactivators

Abstract

The rate of an enzyme-catalysed reaction may sometimes be altered in a specific manner by compounds other than the substrate(s). Activators increase the rate; inhibitors and inactivators decrease it. The study of such agents is of practical importance for several reasons:

• (i) inhibition and activation of enzymes by key metabolites provides the normal means of mnetabolic ‘fine control’ superimposed on the ‘coarse’ control achieved by regulation of the synthesis and breakdown of active enzymes;

• (ii) external interference with metabolism, whether by drugs, pesticides etc. or by undesirable toxic agents, often depends on the inhibition of enzymes;

• (iii) inhibitors, and especially inactivators, provide a powerful tool for studying the chemical mechanisms of enzyme action.