Acetylation
The addition of an acetyl group to a molecule, most commonly to the N-terminus of a peptide. N-terminal acetylation protects peptides from degradation by aminopeptidases and can alter biological activity. It is a common modification in synthetic peptide design.
Technical Context
N-terminal acetylation replaces the free amino group's positive charge with a neutral acetyl group (CH3CO-). In biology, approximately 80% of human proteins are N-terminally acetylated as a co-translational modification. For synthetic therapeutic peptides, N-acetylation serves two main purposes: protection from aminopeptidases that require a free N-terminal amino group, and modulation of receptor binding (some receptors bind better to acetylated peptides). In SPPS, N-acetylation is performed as a simple final step before cleavage from resin, using acetic anhydride or acetyl chloride.