Oacetylation

O-acetylation is the chemical process of introducing an acetyl group (−COCH3) onto an oxygen atom of a molecule, forming an ester. The modification most commonly occurs at hydroxyl groups but can involve other oxygen-containing sites. In organic synthesis, O-acetylation is achieved with acetylating agents such as acetic anhydride or acetyl chloride, often in the presence of a base or catalyst. In biology, O-acetylation is typically catalyzed by O-acetyltransferases that transfer the acetyl group from donors such as acetyl-CoA or acetyl phosphate to an oxygen on the substrate.

Biological examples: In bacteria, O-acetylation of the peptidoglycan component N-acetylmuramic acid at the C6 hydroxyl by O-acetyltransferases like OatA increases resistance to lysozyme and can influence cell wall remodeling. In glycoconjugates, sialic acids (N-acetylneuraminic acid) can be O-acetylated at positions such as C7–C9 by sialic acid O-acetyltransferases, affecting receptor binding and immune recognition. O-acetylation also occurs in other natural products and lipids, where it can alter solubility, acidity, and chemical reactivity.

Detection and significance: Analytical methods include mass spectrometry, NMR, and chromatographic approaches to detect and quantify O-acetyl groups. The presence or absence of O-acetylation can influence biological activity, antigenicity, and antibiotic susceptibility, making it a notable modification in both chemistry and microbiology.