Acetylation

Acetylation (or in IUPAC nomenclature ethanoylation) describes a reaction that introduces an acetyl functional group into a chemical compound. Deacetylation is the removal of an acetyl group. Acetylation (or in IUPAC nomenclature ethanoylation) describes a reaction that introduces an acetyl functional group into a chemical compound. Deacetylation is the removal of an acetyl group. Acetylation refers to the process of introducing an acetyl group (resulting in an acetoxy group) into a compound, namely the substitution of an acetyl group for an active hydrogen atom. A reaction involving the replacement of the hydrogen atom of a hydroxyl group with an acetyl group (CH3 CO) yields a specific ester, the acetate. Acetic anhydride is commonly used as an acetylating agent reacting with free hydroxyl groups. For example, it is used in the synthesis of aspirin, heroin, and THC-O-acetate. Acetylation is an important modification of proteins in cell biology; and proteomics studies have identified thousands of acetylated mammalian proteins. Acetylation occurs as a co-translational and post-translational modification of proteins, for example, histones, p53, and tubulins. Among these proteins, chromatin proteins and metabolic enzymes are highly represented, indicating that acetylation has a considerable impact on gene expression and metabolism. In bacteria, 90% of proteins involved in central metabolism of Salmonella enterica are acetylated. N-terminal acetylation is one of the most common co-translational covalent modifications of proteins in eukaryotes, and it is crucial for the regulation and function of different proteins. N-terminal acetylation plays an important role in the synthesis, stability and localization of proteins. About 85% of all human proteins and 68% in yeast are acetylated at their Nα-terminus. Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. N-terminal Acetylation is catalyzed by a set of enzyme complexes, the N-terminal acetyltransferases (NATs). NATs transfer an acetyl group from acetyl-coenzyme A (Ac-CoA) to the α-amino group of the first amino acid residue of the protein. Different NATs are responsible for the acetylation of nascent protein N-terminal, and the acetylation was found to be irreversible so far.