Cofactor

This is the non-protein part of a complex enzyme. It can contain metal ions (Cu²⁺, Fe²⁺, Mg²⁺, Mn²⁺), which directly participate in catalysis, and various organic compounds (membrane phospholipids), which do not directly participate in catalysis. Cofactors usually bind to a specific protein part of the enzyme (called apoenzyme), which forms the active center of the enzyme. Cofactors can bind tightly or weakly to apoenzymes. A tightly bound cofactor is the enzyme’s prosthetic group, which can only be removed by disrupting the enzyme’s spatial structure. Some enzymes are active only when both a cofactor and a coenzyme are attached. During enzymatic catalysis, metal ions, as cofactors, can perform the following functions: 1) polarize the substrate molecule, making its chemical bonds easier to break, and maintain the transitional state of substrates; 2) attach the substrate to the active enzyme center; 3) attach electrons from the substrate molecule and transfer them to the acceptor.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė