Evidence for an essential arginine residue in the substrate binding site of the mammalian succinate dehydrogenase

Phenylglyoxal and 2,3-butanedione rapidly inactivate membrane-bound or soluble bovine heart succinate dehydrogenase. The inhibition of the enzyme by these reagents is completely prevented by saturating concentration of malonate. The modification of the active site sulfhydryl group by p-chloromercuribenzoate decreases the rate of the enzyme inhibition by phenylglyoxal and abolishes the protective effect of malonate. Kinetic data suggest that the inactivation by phenylglyoxal results from the modification of an essential arginine residue(s) which interacts with dicarboxylate to form the primary enzyme-substrate complex.