Sacetyltransferase

S-acetyltransferase refers to enzymes that catalyze the transfer of an acetyl group from acetyl-CoA to a sulfur-containing acceptor, typically a thiol group on a substrate. The general reaction can be summarized as acetyl-CoA plus a substrate-SH yielding CoA and a substrate S-acetylated at the sulfur atom. This activity is part of the broader family of acyltransferases, and in many cases is described as a sulfur-targeting or S-specific acetyltransferase.

Substrate scope for S-acetyltransferases is diverse and includes small-molecule thiols, such as cysteine-containing metabolites or peptide thiols, as well as protein thiols in which cysteine residues become S-acetylated. Some enzymes show promiscuity among acetyltransferase substrates, exhibiting both S- and, less commonly, N- or O-acetylation activities. Mechanistically, many acyltransferases operate via a catalytic mechanism that forms a transient enzyme–acetyl intermediate and stabilizes a tetrahedral intermediate, with active-site residues acting to activate the thiol and Orient the acetyl donor for transfer. The exact details can vary among different enzymes and folds, including members of the GNAT superfamily in some contexts.

Biological significance varies by organism and context. S-acetylation can modulate the function, localization, or stability of sulfur-containing substrates and can be involved in redox regulation or detoxification processes. In many systems, S-acetyltransferase activity is studied as part of the broader regulation of protein and metabolite acetylation, and the term is sometimes used descriptively rather than as a formal, universally standardized enzyme class. Cross-references include acetyltransferases, protein S-acetylation, and GNAT-related enzymes.