Acetylation

Acetylation describes a reaction, usually with acetic acid, that introduces an acetyl radical into an organic compound.

Moreover, it is that process of introducing an acetyl group into a compound, specifically, the substitution of an acetyl radical for an active hydrogen atom. A reaction involving the replacement of the hydrogen atom of an hydroxyl group with an acetyl radical (CH₃ CO) to yield a specific ester, the acetate. Acetic anhydride is commonly used as an acetylating agent reacting with free hydroxyl groups.

In biology, acetylation is used as a post-translational modification of proteins. For example, histones are acetylated and deacetylated as part of gene regulation. Typically, these reactions are catalyzed by enzymes with "histone acetyltransferase" (HAt) or "histone deacetylase" (HDAc) activity. The source (target) of the acetyl group in histone (de)acetylation is Acetyl Coenzyme A (AcCoA).