small nonprotein molecules and metal ions directly participate in substrate binding or catalysis known as coenzymes, cofactors or prosthetic groups
Coenzyme- Nonprotein, organic, LMW, dialysable substance associated with enzyme action
Cofactor- metal ions bound loosely with enzymes
Prosthetic groups- tight and stable association with enzyme.
classified in the basis of
1. precursor molecule
2. group transfer
