Carboxylesterase

In enzymology, a carboxylesterase is an enzyme that catalyzes the chemical reaction


 * a carboxylic ester + H2O $$\rightleftharpoons$$ an alcohol + a carboxylate

Thus, the two substrates of this enzyme are carboxylic ester and H2O, whereas its two products are alcohol and carboxylate.

Most enzymes from this group belong to the superfamily of hydrolases with alpha/beta protein fold (so called Alpha/beta hydrolase fold), specifically those acting on carboxylic ester bonds. Some exceptions include an esterase with beta-lactamase like structure. The carboxylesterase family of evolutionarily related proteins (those with clear sequence homology to each other) includes a number of proteins with different substrate specificities, such as acetylcholinesterases.

Nomenclature
Carboxylesterase is an enzyme that capable of hydrolyzing a wide variety of carboxylic acid esters. Although its metabolic function is unclear, the enzyme is widely distributed in nature, being especially common in mammalian liver. Carboxylesterase belongs to the class of serine hydrolases which includes Chymotrypsin and Acetylcholinesterase.

The systematic name of this enzyme class is carboxylic-ester hydrolase. Examples of carboxyesterases include:


 * ali-esterase,
 * alpha-carboxylesterase,
 * B-esterase,
 * butyrate esterase,
 * butyryl esterase,
 * carboxyesterase,
 * carboxyl ester hydrolase,
 * carboxylate esterase,
 * carboxylic acid esterase,
 * carboxylic esterase,
 * esterase A,
 * esterase B,
 * esterase D,
 * methylbutyrase,
 * methylbutyrase,
 * methylbutyrate esterase,
 * monobutyrase,
 * nonspecific carboxylesterase,
 * procaine esterase,
 * propionyl esterase,
 * serine esterase,
 * triacetin esterase,
 * vitamin A esterase, and
 * cocaine esterase.

The last enzyme also participates in alkaloid biosynthesis.

Genes
Humans genes that encode carboxylesterase enzymes include:
 * CES1
 * CES2
 * CES3
 * CES4
 * CES7
 * CES8

Structural studies
As of late 2007, 38 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and.