Trypsin is a serine protease that works enzymatically by using a mixture of base, acid, and covalent catalysis. The protein uses serine in its active site to interact covalently with the substrate. To create a nucleophilic attack, a histadine group activates a serine group via base catalysis and covalent catalysis follows. This forms a tetrahedral intermediate, which is followed by acid catalysis from the -NH2 of the of the c-terminus, resulting in a broken peptide bond in the substrate. The enzyme-substrate complex is present, and hydrolysis occurs which ultimately releases the c-terminal chain of the substrate and forms a new bond between water and the carbonyl carbon of the enzyme-substrate complex. The covalent C-O bond of the substrate-enzyme complex is broken, and the enzyme is reformed as the product is released.
This structure was found from
