Studies on the Mechanism of Action of Acetyl Coenzyme A Carboxylase

Studies presented here, with the criterion of the degree of binding of the biotin derivatives obtained from acetyl coenzyme A carboxylase to avidin, show that these compounds have an intact ureido ring, eliminating the diamine derivative as an intermediate in the carboxylation. With the use of carboxyl-14C-biotin acetyl- and propionyl-CoA carboxylases, it has been possible to show both in vivo and in vitro that no turnover of the ureido carbon of biotin occurs in the carboxylation reaction. The 1‘-N-methoxycarbonylbiotin methyl ester was isolated from the acetyl-CoA carboxylase substantiating the hypothesis that the 1‘-N-carboxamide of enzyme-bound biotin is an intermediate in these carboxylation reactions.