Covalent Modification of Serine
- Diisopropyl fluorophosphate (DFP) is a nerve gas that forms a covalent bond with a
reactive serine residue found in many protease and esterase enzymes
- In the active site of chymotrypsin, shown above, the hydroxyl group of Ser195 attacks the
phosphorus atom in DFP, forming a phosphoryl linkage that inactivates the enzyme
- In addition to identifying active site residues for analytical purposes, organic phosphorus
compounds such as DFP were developed as toxic agents for military purposes, and also for use
as insecticides