<Tr> <Th> PDB </Th> <Td> RCSB PDB; PDBe; PDBj </Td> </Tr> <Tr> <Th> PDBsum </Th> <Td> structure summary </Td> </Tr> <P> Trypsin (EC 3.4. 21.4) is a serine protease from the PA clan superfamily, found in the digestive system of many vertebrates, where it hydrolyzes proteins . Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen produced by the pancreas, is activated . Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when either is followed by proline . It is used for numerous biotechnological processes . The process is commonly referred to as trypsin proteolysis or trypsinisation, and proteins that have been digested / treated with trypsin are said to have been trypsinized . Trypsin was discovered in 1876 by Wilhelm Kühne . </P> <P> In the duodenum, trypsin catalyzes the hydrolysis of peptide bonds, breaking down proteins into smaller peptides . The peptide products are then further hydrolyzed into amino acids via other proteases, rendering them available for absorption into the blood stream . Tryptic digestion is a necessary step in protein absorption, as proteins are generally too large to be absorbed through the lining of the small intestine . </P>

Where is protease used in the digestive system