On the Possible Involvement of a Carbonyl Phosphate Intermediate in the Adenosine Triphosphate-dependent Carboxylation of Biotin

Biotin carboxylase, the component of Escherichia coli acetyl CoA carboxylase which carries out the ATP-dependent carboxylation of biotin, catalyzes phosphoryl transfer from carbamyl phosphate to ADP to form ATP. The latter reaction is dependent upon free d-biotin and divalent cation and, like the carboxylation of free d-biotin, is activated by ethanol. The participation of carbamyl phosphate (an analogue of carbonyl phosphate) in the phosphoryl transfer reaction is consistent with a mechanism of carboxybiotin formation in which carbonyl phosphate is an intermediate.