Synthesis and Enzymic Conversion of Isobutanoyl‐carba(dethia)‐Coenzyme A

Acyl coenzyme A analogues in which the sulphur is replaced by methylene are stable to hydrolysis and can be used to investigate enzymatic reaction mechanisms. With this idea in mind we synthesized isobutanoyl‐carba(dethia)‐coenzyme A (isobutanoyl‐CH 2 CoA) and monitored its reaction in enzymatic systems. A cell‐free extract of Pseudomonas putida (ATCC 21244) complemented with FAD, phenazine methosulphate, and DCIP catalyzed the conversion of isobutanoyl‐CH 2 CoA into methacryloyl‐CH 2 CoA and β‐hydroxyisobutanoyl‐CH 2 CoA. The latter could not be further oxidized to the aldehyde and carboxyl level, indicating that these oxidations normally occur after hydrolysis of the CoA ester.