3-hydroxy-3-methylglutaryl-CoA lyase [SEP] found in taxon
3-hydroxy-3-methylglutaryl-CoA lyase
3-hydroxy-3-methylglutaryl-CoA lyase (or HMG-CoA lyase) is an enzyme that in human is encoded by the HMGCL gene located on chromosome 1. It is a key enzyme in ketogenesis (ketone body formation). It is a ketongenic enzyme in the liver that catalyzes the formation of acetoacetate from HMG-CoA within the mitochondria. It also plays a prominent role in the catabolism of the amino acid leucine. 
Structure.
The HMGCL gene encodes a 34.5-kDa protein that is localized to the mitochondrion
end of a beta barrel structure. In addition, the lysine 48 residue which is mutated in patients with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency is also found to be necessary for substrate binding.
Function.
The HMGCL protein plays an essential role in breaking down dietary proteins and fats for energy. It catalyzes the reaction:
(S)-3-hydroxy-3-methylglutaryl-CoA = acetyl-CoA + acetoacetate.
and requires a divalent metal ion as co-factor.
The enzyme is required for ketogenesis in the liver, and is also responsible