EC number 3.1.2.2 IntEnz IntEnz view ExPASy NiceZyme view | CAS number 9025-87-0 BRENDA BRENDA entry KEGG KEGG entry | |
In enzymology, a palmitoyl-CoA hydrolase (EC 3.1.2.2) is an enzyme in the family of hydrolases that specifically acts on thioester bonds. It catalyzes the hydrolysis of long chain fatty acyl thioesters of acyl carrier protein or coenzyme A to form free fatty acid and the respective thiol.
Contents
Thus, the two substrates of this enzyme are palmitoyl-CoA and H2O, whereas its two products are CoA and palmitate. It has a strict specificity for thioesters with a chain link greater than C10.
These enzymes are localized in almost all cellular compartments, such as endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. They are highly regulated by peroxisome proliferator activated receptors (PPARs), which led to their involvement in lipid metabolism. The enzyme is up-regulared during times of increased fatty acid oxidation, which suggests that this enzyme has a potential role the peroxisomal beta-oxidation.
The systematic name of this enzyme class is palmitoyl-CoA hydrolase. Other names in common use include long-chain fatty-acyl-CoA hydrolase, palmitoyl coenzyme A hydrolase, palmitoyl thioesterase, palmitoyl coenzyme A hydrolase, palmitoyl-CoA deacylase, palmityl thioesterase, palmityl-CoA deacylase, fatty acyl thioesterase I, and palmityl thioesterase I.
Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1TBU, 2Q2B, and 2QQ2.
Mechanism
At a subcellular level, palmitoyl-CoA hydrolase is localized in the endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. Studies have shown that in rat's that are fed high fat diets, palmitoyl-CoA hydrolase activity in the liver increased. While the details of the mechanism is not know, the results suggest that there is an "induction" mechanism taking place for palmitoyl-CoA hydrolase and peroxisomal beta-oxidation enzymes.
Disease Relevance
Diabetes is the most common cause of liver disease in the U.S., specifically from type 2 diabetes. Studies have been done to show that, while there is not direct correlation between palmitoyl-CoA hydrolase and diabetes, streptozotocin-induced diabetes significantly decreased rat liver palmitoyl-CoA hydrolase. This led to high levels of fatty acyl-CoA being present in the liver, which shows that a diseased liver cannot regulate the amount of fatty acyl-CoA that is present versus a normal, healthy liver. A defect in acyl-CoA degradation in livers can produce hyperammonemia and hyproglycemia.