The reaction of chymotrypsin and diisopropylphosphorofluoridate II. The structure of two DP-substituted peptides from chymotrypsin-DP

1. 1. The amino acid sequence of two diisopropylphosphoryl-substituted peptides obtained from α-chymotrypsin-DP by enzyme hydrolysis was established as: glycyl-aspartyl-seryl-glycyl-glycyl-prolyl-leucine and glycyl-aspartyl-seryl-glycyl-glycyl-proline, respectively. 2. 2. The experimental results strongly suggest that the diisopropylphosphoryl group is attached to the hydroxyl group of the seryl residue. 3. 3. The significance of the investigated peptides in respect to the DFP-binding and ester-splitting ability of α-chymotrypsin is discussed.