STRUCTURAL ELEMENTS OF TRIMERESURUS-FLAVOVIRIDIS SERUM INHIBITORS FORRECOGNITION OF ITS VENOM PHOSPHOLIPASE A(2) ISOZYMES

Fire inhibitors (PLI-I-V) against Trimeresurus flavoviridis (Tf, habu snake, Crotalinae) venom phospholipase A(2) (PLA(2)) isozymes have bee n isolated from its serum. PLI-I, which is composed of two repeated th ree-finger motifs, and PLI-IV and PLI-V, which contain a sequence simi lar to the carbohydrate recognition domain (CRD) of C-type lectins, me re er;pressed in the forms fused with glutathione S-transferase (GST), The resulting GST-PLIs showed ability to bind to three Tf venom PLA2 isozymes, The binding study with the truncated forms indicated that on e of tno three-finger motifs of PLI-I was able to bind to PLA(2) isozy mes, The N-terminal 37-amino acid fragment and the CRD-like domain of PLI-IV and PLI-V mere bound to PLA(2) isozymes. On the other hand, the ir C-terminal 12-amino acid segment also associated,vith PLA2 isozymes . When either of two units of a hydrophobic tripeptide in this sequenc e was replaced by trialanine, the binding was completely abolished, in dicating that the C-terminal hydrophobic cores of PLI-IV and PLI-V mer e critically responsible for the binding to venom PLA(2) isozymes. (C) 1998 Federation of European Biochemical Societies.