Trypsin is a digestive enzyme that cleaves peptide bonds (a serine protease). It cuts proteins only at carboxyl side of lysine and arginine residues (endopeptidase) by hydrolysis. Aspartate (Asp 189) residue located in the catalytic pocket (S1) of trypsin is responsible for attracting and stabilizing positively-charged lysine and/or arginine. The optimum pH for Trypsin is 8.

Trypsin is produced in the pancreas in the form of trypsinogen, and is then transported to the small intestine, where begins the digestion of proteins to polypeptides and amino acids. Trypsin is an autocatalytic enzyme ; that is, trypsin catalyzes the formation of trypsinogen to trypsin. A small amount of another enzyme, enterokinase , is required to catalyze the initial reaction of trypsinogen to trypsin.

Many trypsin preparations contain some ...

Trypsin is often modified by TPCK , Tosyl Phenylalanyl Chloromethyl Ketone, which will inactivate chymotrypsin. This is important because in some applications, like mass spectrometry the specifity of cleavage is important.

Trypsin should be stored at very cold temperatures (between -20 and -5C) to prevent denaturation.