coenzyme

https://doi.org/10.1351/goldbook.C01126
The dissociable, low-relative-molecular-mass active group of an @E02159@ which transfers chemical groups, hydrogen or electrons. A coenzyme binds with its associated protein (@A00417@) to form the active enzyme (@H02836@).
Source:
PAC, 1994, 66, 2587. (Glossary of bioanalytical nomenclature - Part 1: General terminology, body fluids, enzymology, immunology (IUPAC Recommendations 1994)) on page 2593 [Terms] [Paper]