Abstract
An enzyme fraction which catalyzes the reduction of trans-2-enoyl-coenzyme A (trans-2-enoyl-CoA) to the corresponding saturated acyl-CoA derivative was separated from Escherichia coli (E. coli) extracts. The enzyme utilized reduced nicotinamide adenine dinucleotide phosphate (NADPH) as a sole electron donor for the reduction of substrates, and it acted on acyl-CoA substrates, but not on acyl-carrier protein esters. Therefore, the name NADPH-dependent trans-2-enoyl-CoA reductase was proposed for this enzyme. The reductase was stable at around pH 7-8, and was active over a wide pH range between 6 and 9. It had a functional thiol group and was readily inhibited by thiol reagents such as p-hydroxymercuribenzoic acid, and by cupric and some other metal ions. The enzyme was induced when E. coli cells were cultured in a medium containing oleic acid. These results suggest that this reductase does not participate in the de novo synthesis of fatty acids but is a new enzyme, although its physiological role is uncertain at the present stage.
