acylenzyme

Acylenzyme is a term used in enzymology to describe enzymes whose catalytic cycle does not involve a covalently bound acyl-enzyme intermediate. The concept contrasts with mechanisms in which a covalent acyl-enzyme adduct forms during turnover, a feature common to many serine hydrolases.

In an acylenzyme framework, substrate turnover would proceed through non-covalent stabilization of transition states, metal ion catalysis, or rapid proton transfers, without the formation of a stable covalent acyl-enzyme intermediate. This emphasizes non-covalent catalysis or alternative catalytic strategies as the primary drivers of reaction progress.

The term is not widely standardized in the primary literature. Many researchers prefer to describe mechanism in terms of covalent versus non-covalent catalysis, or by explicitly noting the presence or absence of covalent intermediates, rather than applying the label “acylenzyme” as a formal category. As a result, usage of the term can be inconsistent and sometimes speculative.

If used, the concept of acylenzyme highlights the diversity of catalytic strategies in biology and may have implications for inhibitor design and enzyme engineering by drawing attention to non-covalent or metal-assisted pathways. However, concrete, broadly accepted examples remain limited, and the term should be applied with caution pending clearer consensus in the field.

See also acyl-enzyme intermediate; covalent catalysis; non-covalent catalysis; metalloenzymes.