Function
Trypsin is a serine protease released by the pancreas and secreted into the duodenum that acts as a digestive enzyme that catalyzes the hydrolysis of peptide bonds, specifically for positively charged residues (K, R, H). The mechanism in which the enzyme acts as a protease is as follows:
1. Nucleophillic and base catalysis by enzyme to substrate to form tetrahedral intermediate at carbonyl group of scissile peptide.
2. Acid catalysis breaks the tetrahedral intermediate through cleaving of the scissile peptide bond to form an acyl-enzyme intermediate.
3. The amine product is replaced by H2O and subsequently released from the enzyme/substrate complex.
4. Base catalysis by enzyme; H2O forms a covalent bond with the carbonyl group of the N-terminal peptide, leading to another tetrahedral intermediate
5. Acid catalysis by the breaking of the C-O covalent bond of the tetrahedral intermediate, releasing the peptide from the enzyme substrate complex. Once the peptide is released, the enzyme once again becomes active. [1].
Disease
Relevance
Structural highlights
Histidine 57 - Acid Catalysis Residue
Aspartic Acid 102 - Important Residue in Stabilization of Catalytic Mechanism
