Peptidases are classified according to specificity and catalytic type. Classification by specificity depends on the position of the peptide bond cleaved within the peptide or protein chain. Classification by catalytic type depends on the nature of the nucleophile in the hydrolytic reaction. The classification adopted by Enzyme Nomenclature is based on specificity, although carboxypeptidases and endopeptidases are subdivided by catalytic type. Oligopeptidases are endopeptidases which cleave internal bonds in peptides, but are incapable of cleaving bonds in proteins.
Proteinases are endopeptidases which can cleave bonds in proteins.
All enzymes capable of cleaving peptide bonds are known as peptidases or proteases .