The reaction is catalysed in the reverse direction. This enzyme, isolated from the bacterium Rhodobacter sphaeroides, catalyses (E)-but-2-enoyl-CoA-dependent oxidation of NADPH in the presence of CO2. When CO2 is absent, the enzyme catalyses the reduction of (E)-but-2-enoyl-CoA to butanoyl-CoA, but with only 10% of maximal activity (relative to (E)-but-2-enoyl-CoA carboxylation).
Enzymatic reactions [BR:br08201]
1. Oxidoreductase reactions
1.3 Acting on the CH-CH group of donors
1.3.1 With NAD+ or NADP+ as acceptor
1.3.1.85
R09291 (2S)-Ethylmalonyl-CoA + NADP+ <=> Crotonoyl-CoA + CO2 + NADPH + H+