Hydrolase

Hydrolase is a broad class of enzymes that catalyze hydrolysis reactions, in which a water molecule is used to break a chemical bond within a substrate. They belong to the third class (EC 3) of the enzyme commission numbering system and act on a wide range of bonds, including esters, amides, glycosidic bonds, phosphoesters, and phosphodiesters. The result is typically two molecules or a molecule plus a leaving group.

Mechanisms among hydrolases vary, reflecting their diverse substrates. Some use a catalytic triad or dyad, as seen in serine proteases, where serine, histidine, and aspartate cooperate to activate water and facilitate bond cleavage. Others rely on cysteine residues or metal ions to activate water or stabilize transition states. Common reaction types include proteolysis, lipolysis, glycoside hydrolysis, and dephosphorylation. Water serves as the nucleophile that breaks the target bond.

Biological roles and distribution are broad. Hydrolases operate inside cells and outside, in extracellular spaces, digestive tracts, and lysosomes. Digestive enzymes such as proteases and lipases, lysosomal hydrolases that recycle macromolecules, and various glycosidases continually remodel biological macromolecules. Deficiencies in certain lysosomal hydrolases can cause metabolic diseases, highlighting their essential physiological roles.

Applications of hydrolases extend across industry and medicine. They are used in detergents, food processing, and biocatalysis, where they enable stereospecific synthesis and degradation under mild conditions. Research and biotechnology increasingly leverage hydrolases for sustainable synthesis, waste valorization, and therapeutic development.