hydrolaseesterase

Hydrolases are a broad class of enzymes that catalyze the hydrolysis of chemical bonds, incorporating water into their substrates. Esterases are a well-known subgroup of hydrolases that specifically cleave ester bonds, yielding an alcohol and an acid (or related derivatives). In this sense, esterases are hydrolases, but not all hydrolases act on esters.

Mechanism and classification vary among esterases. Many operate as serine hydrolases that use a catalytic triad, typically serine, histidine, and an acidic residue, to activate a water molecule for nucleophilic attack. Others rely on metal ions or distinct catalytic strategies. Substrate specificity ranges from simple aryl or alkyl esters to complex lipid esters. Notable examples include carboxylesterases, cholinesterases, and lipases, each adapted to different biological contexts and substrates.

Biological roles are diverse. Esterases participate in digestion and nutrient assimilation (for example, lipases act on dietary fats), detoxification of xenobiotics, and metabolism of a wide range of ester-containing compounds. In medicine and biology, cholinesterases regulate neurotransmission by hydrolyzing acetylcholine, while carboxylesterases contribute to drug metabolism and the activation or deactivation of ester-containing pharmaceuticals.

Applications and significance. Esterases are used as biocatalysts in chemical synthesis and pharmaceutical processing, including the resolution of chiral esters. They also play roles in environmental cleanup by degrading ester-containing pollutants and in biosensing and diagnostic contexts. Clinically, inhibitors or deficiencies of specific esterases can have profound physiological effects, underscoring their importance in health and disease.

Notes. The term hydrolase covers many enzyme families; esterases are a major, well-characterized subset focused on ester bond hydrolysis.