The protein part of an enzyme without the cofactor necessary for
catalysis. The cofactor can be a metal ion, an organic molecule (
coenzyme ), or a combination of both.
Source:
PAC, 1994, 66, 2587
(Glossary of bioanalytical nomenclature - Part 1: General terminology, body fluids,
enzymology, immunology (IUPAC Recommendations 1994))
on page 2593