6.2.1.13 ATP + acetate + CoA = ADP + phosphate + acetyl-CoA - 6.2.1.13 ATP + acetate + CoA = ADP + phosphate + acetyl-CoA reaction mechanism and structural modelling, formation of enzyme-bound acetyl phosphate and enzyme phosphorylation at His257alpha, overview 6.2.1.13 ATP + acetate + CoA = ADP + phosphate + acetyl-CoA reaction mechanism: the formation of enzyme-bound acetyl phosphate and enzyme phosphorylation at His-257alpha, respectively, proceeds in analogy to succinyl-CoA synthetases. In contrast to succinyl-CoA synthetases, in acetyl-CoA synthetase the phosphoryl group is transferred from the His-257alpha to ADP via transient phosphorylation of a second conserved histidine residue in the beta-subunit, His-71alpha. It is proposed that acetyl-CoA synthetase reaction follows a four-step mechanism including transient phosphorylation of two active site histidine residues 6.2.1.13 ATP + acetate + CoA = ADP + phosphate + acetyl-CoA the enzyme uses a four-step reaction mechanism including an additional phosphoryl transfer step, the important His252, located in the beta subunit, is invovled