Hydroxymethylglutaryl-CoA synthase

In enzymology, a hydroxymethylglutaryl-CoA synthase is an enzyme that catalyzes the chemical reaction


 * acetyl-CoA + H2O + acetoacetyl-CoA $$\rightleftharpoons$$ (S)-3-hydroxy-3-methylglutaryl-CoA + CoA

The 3 substrates of this enzyme are acetyl-CoA, H2O, and acetoacetyl-CoA, whereas its two products are (S)-3-hydroxy-3-methylglutaryl-CoA and CoA.

This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:acetoacetyl-CoA C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming). Other names in common use include (S)-3-hydroxy-3-methylglutaryl-CoA acetoacetyl-CoA-lyase, (CoA-acetylating), 3-hydroxy-3-methylglutaryl CoA synthetase, 3-hydroxy-3-methylglutaryl coenzyme A synthase, 3-hydroxy-3-methylglutaryl coenzyme A synthetase, 3-hydroxy-3-methylglutaryl-CoA synthase, 3-hydroxy-3-methylglutaryl-coenzyme A synthase, beta-hydroxy-beta-methylglutaryl-CoA synthase, HMG-CoA synthase, acetoacetyl coenzyme A transacetase, hydroxymethylglutaryl coenzyme A synthase, and hydroxymethylglutaryl coenzyme A-condensing enzyme. This enzyme participates in 3 metabolic pathways: synthesis and degradation of ketone bodies, valine, leucine and isoleucine degradation, and butanoate metabolism.

Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes, , , and.