The inhibition of succinate dehydrogenase by oxaloacetate

Abstract

The inhibition of soluble succinate dehydrogenase (succinate:(acceptor) oxido-reductase, EC 1.3.99.1) by oxaloacetate is preceded by a lag during which the degree of the inhibition gradually increases. A similar lag precedes a partial reversal of the inhibition by increasing the concentration of substrate. Succinate dehydrogenase, which has been pretreated with oxaloacetate and from which most of the oxaloacetate has been removed, does not exhibit its full activity unless preincubated with succinate or malonate; preincubation with phosphate or micellar phospholipids is also partly effective. The ability of soluble succinate dehydrogenase to reconstitute the succinate oxidase system is irreversibly lost after pretreatment with oxaloacetate. It is suggested that oxaloacetate may either bind rather tightly with the enzyme or promote a reversible conformation change leading from the active form of the dehydrogenase to an inactive one.