ABSTRACT
Enoate reductase exclusively splits off the (4S)-hydrogen atom from NADH. Enoate reductase or clostridia containing the enzyme catalyze the reduction of α,β-unsaturated aldehydes. Enoate reductase in the reduced form is extremely oxygen sensitive and relatively stable against hydrogen peroxide. The substrate specificity of the enoate reductase from Clostridium sporogenes and other proteolytic clostridia is rather selective. Enzymatic enoate reductase determinations in crude extracts of Clostridium thermoaceticum are prevented by the occurrence of overlaying reactions using NADH or reduced viologens. Products of preparative hydrogenations of enoates using whole cells of C. thermoaceticum show the stereospecificity typical for the reduction of nonactivated α,β-unsaturated carboxylates by enoate reductases. The purification of enoate reductase is straightforward by combined chromatography of crude extract on DEAE-Sepharose and spherical hydroxylapatite. The complex D of 2-enoate and the enzyme in the oxidized state decomposes into the 2-enoate and the enzyme.
