acetylation

Acetylation is a chemical reaction that introduces an acetyl group (CH3-CO-) into a substrate. In organic synthesis, the acetyl moiety is typically delivered by acetylating agents such as acetyl chloride, acetic anhydride, or acetyl coenzyme A. The reaction proceeds through nucleophilic attack at the electrophilic carbonyl carbon, forming esters, amides, or related acetyl derivatives depending on the nucleophile (oxygen, nitrogen, or sulfur).

In chemical contexts, acetylation is widely used to mask reactive functional groups (protecting groups), to prepare esters such as ethyl acetate, and to produce acetylated polymers and natural products. Industrially important examples include cellulose acetate, used in films and fibers, and acetylated amines and esters prepared for pharmaceutical and material applications.

In biology, acetylation denotes the addition of an acetyl group to biomolecules, most famously lysine residues on histone proteins. Histone acetyltransferases transfer the acetyl group from acetyl-CoA to target lysines, reducing the positive charge and promoting a more open chromatin state that can enhance gene expression. Deacetylases remove the group, contributing to transcriptional repression. Non-histone proteins, metabolic enzymes, and some regulatory RNAs can also be acetylated, influencing activity, stability, or localization. Acetylation is a reversible regulatory mechanism; non-enzymatic acetylation can occur under certain metabolic conditions with high acetyl-CoA or acetyl-phosphate levels.

Safety considerations include the use of reactive acetylating agents, which are typically corrosive and require proper ventilation and protective equipment.