The inactivation of succinate dehydrogenase by bromopyruvate

Abstract

1. 1. Bromopyruvate has been found to be a potent irreversible inhibitor of succinate dehydrogenase (succinate:(acceptor) oxidoreducatase, EC 1.3.99.1). While the kinetics of inactivation show a saturation effect, they do not fit the simple model for an active-site-directed irreversible inhibitor. Instead, a concentration dependent plateau is observed. A similar phenomenon occurs when N-ethylmaleimide is the alkylating agent. Reversible inhibitors and substrates protect succinate dehydrogenase from activation by bromopyruvate and N-ethylmaleimide. Both reagents have similar relative reactivities toward the enzyme and 2-nitro-5-thiolbenzoic acid dianion. 2. 2. The absorption and dithionite bleaching spectra are not greatly affected by the reaction of enzyme with bromopyruvate, but the ability of succinate to bleach is lost. A decrease in hydrogen exchange capacity parallels the decrease in assay activity. © 1971.