Coenzyme A Transferase

An enzyme-coenzyme A intermediate has been isolated by molecular exclusion chromatography on Sephadex after incubation of succinyl-CoA:3-keto acid coenzyme A transferase with acetoacetyl-CoA or succinyl-CoA. The intermediate is enzymatically active in that it reacts with succinate to give succinyl-CoA. After hydrolysis the presence of coenzyme A was identified by fluorometric assay with α-ketoglutarate dehydrogenase. Free coenzyme A and the acyl moieties of succinyl-CoA and acetoacetyl-CoA are not bound to the enzyme under conditions in which the intermediate is isolated. The intermediate is labile to base and stable to dilute acid. It undergoes hydrolysis at pH 7.4 with a half-time of 30 min. It reacts with 0.007 m sodium borohydride to give an inactive enzyme and with tritiated borohydride to give a tritium-labeled protein.