Tryptophan Residues Involved in the Binding of Chlorinated Pesticides by Rhizopus delemar C-Lipase : Isolation of Tryptophan-Containing Peptides

Tryptophan (Trp) residues involved in the binding of 1, 1, 1-trichloro-2, 2-bis(4-chlorophenyl)ethane (DDT), 2, 2-bis(4-chlorophenyl)ethane (DIM) and dichlorobenzophenone (DCBP) by Rhizopus delemar C-lipase were identified on the basis of knowledge of amino acid sequences around the Trp residues. Eight Trp- or modified Trp-containing peptides were isolated from each of 1 : 1, 2 : 1 and 9 : 1 pesticide-lipase complexes modified by 2-hydroxy-5-nitrobenzylation under three different conditions, and the peptides were identified.The results confirm the previous tentative assignment of the Trp residues involved in the ligand binding, which was presented on the basis of comparison of their modification patterns.