Unenzymes
Unenzymes is a term that appears only sporadically in biochemical literature. It is not part of the standard taxonomy of enzymes, and its meaning varies between sources. In a narrow sense, unenzymes refer to substances or molecular systems that accelerate chemical reactions but do not fit the conventional definition of enzymes as proteins with a well-defined active site formed by specific catalytic residues. The label is often used to highlight catalytic activity that lacks a classic enzyme architecture or to describe catalysts that operate without a fixed active site.
Interpretations of the concept include non-protein catalysts with biological relevance, metal ion– or cofactor-mediated catalysis, or
Critics argue that unenzyme is a vague label that can confuse rather than clarify, and many scientists
See also: enzyme, ribozyme, metalloenzyme, enzyme mimics, catalysis.