Reaction: 2 acetyl-CoA = CoA + acetoacetyl-CoA (overall reaction)
(1a) acetyl-CoA + [acetyl-CoA C-acetyltransferase]-L-cysteine = [acetyl-CoA C-acetyltransferase]-S-acetyl-L-cysteine + CoA
(1b) [acetyl-CoA C-acetyltransferase]-S-acetyl-L-cysteine + acetyl-CoA = acetoacetyl-CoA + [acetyl-CoA C-acetyltransferase]-L-cysteine
For diagram of the reaction click here or click here
Other name(s): acetoacetyl-CoA thiolase; β-acetoacetyl coenzyme A thiolase; 2-methylacetoacetyl-CoA thiolase [misleading]; 3-oxothiolase; acetyl coenzyme A thiolase; acetyl-CoA acetyltransferase; acetyl-CoA:N-acetyltransferase; thiolase II; type II thiolase
Systematic name: acetyl-CoA:acetyl-CoA C-acetyltransferase
Comments: The enzyme, found in both eukaryotes and prokaryotes, catalyses the Claisen condensation of an acetyl-CoA and an acyl-CoA (often another acetyl-CoA), leading to the formation of an acyl-CoA that is longer by two carbon atoms. The reaction starts with the acylation of a nucleophilic cysteine at the active site, usually by acetyl-CoA but potentially by a different acyl-CoA, with concomitant release of CoA. In the second step the acyl group is transferred to an acetyl-CoA molecule. cf. EC 2.3.1.16, acetyl-CoA C-acyltransferase.
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, GTD, KEGG, MetaCyc, PDB, CAS registry number: 9027-46-7
References:
1. Lynen, F. and Ochoa, S. Enzymes of fatty acid metabolism. Biochim. Biophys. Acta 12 (1953) 299-314. [PMID: 13115439]
2. Stern, J.R., Drummond, G.I., Coon, M.J. and del Campillo, A. Enzymes of ketone body metabolism. I. Purification of an acetoacetate-synthesizing enzyme from ox liver. J. Biol. Chem. 235 (1960) 313-317. [PMID: 13834445]