What is "carboxylesterase"

n. (context enzyme English) Any enzyme that catalyses the hydrolysis of a carboxylic ester

In enzymology, a carboxylesterase or carboxylic-ester hydrolase is an enzyme that catalyzes a chemical reaction of the form

a carboxylic ester + HO $\rightleftharpoons$ an alcohol + a carboxylate

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

Most enzymes from this group are serine hydrolases belonging to the superfamily of proteins with alpha/beta hydrolase fold. Some exceptions include an esterase with beta-lactamase like structure .

Carboxylesterases are widely distributed in nature, and are common in mammalian liver. Many participate in phase I metabolism of xenobiotics such as toxins or drugs; the resulting carboxylates are then conjugated by other enzymes to increase solubility and eventually excreted.

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.