desacylation

Desacylation, sometimes called deacylation, is the chemical and biochemical process of removing an acyl group from a molecule. An acyl group is a carbonyl-containing substituent such as an acetyl group or a fatty acyl chain that is bound to the molecule through an ester, amide, or thioester linkage. Desacylation yields a des-acyl derivative and a free carboxylate. While some instances occur non-enzymatically under certain conditions, in biological systems desacylation is typically catalyzed by enzymes.

In biology, desacylation is carried out by hydrolase enzymes that cleave the acyl–bond. Esterases hydrolyze esters, while amidases or thioesterases act on amide or thioester linkages. Protein-linked acyl groups can also be removed by depalmitoylation, which modulates protein localization and signaling. Acyl-protein thioesterases (such as APT1 and APT2) are examples of enzymes that mediate depalmitoylation. In some cases, specific acyl groups on signaling molecules are removed by hydrolysis, producing desacylated forms with distinct activities; for example, desacyl ghrelin is the unacylated form of ghrelin with potentially different biological effects.

Biological and medical relevance includes regulation of protein function, localization, and signaling pathways. Desacylation can influence the stability and activity of signaling molecules and enzymes, and it can modify the pharmacokinetics and activity of acylated drugs or prodrugs. The study of desacylation intersects with metabolism, cell signaling, and pharmacology, reflecting the broader importance of acyl group turnover in biological systems. See also deacylation, hydrolysis, depalmitoylation, ghrelin.