Protease, also known as peptidase or proteinase, is any enzyme that catalyzes the breakdown of proteins into smaller components of peptide fractions and amino acids. This process is known as proteolysis. Proteases are found in all organisms, including animals, plants, viruses and bacteria.
Proteases can be categorized into endopeptidases, which attack interior peptide bonds, and exopeptidases, which attack bonds adjacent to a free amino or carboxyl group. In order for digestion of protein to take place, several proteases are normally required. One example of a protease is trypsin, which digests proteins in the anterior portion of the small intestine and activates other proteases. Other digestive proteases include pepsin and chromotrypsin.