Explain about enzymes

All enzymes are proteins. Many enzyme  proteins lack catalytic activity in the absence of a non-protein component, called a 'co-factor'. In this case, the inactive protein component of an enzyme is termed the 'apoenzyme' and the active enzyme, including the cofactor, the 'holoenzyme'. The cofactor may be an organic molecule, when it is known as a 'coenzyme' or it may be a metal ion.