Structure-Activity Relationships and Immunochemical Studies on Cobrotoxin.

摘要

Cobrotoxin, a neurotoxic crystalline protein,was isolated from the venom of Taiwan cobra (Naja naja atra) and was proved to be the main toxic protein in cobra venom. The two-dimensional structure of the toxin has recently been established,permits a study of structure-function relationships. Preceding studies on the chemical modification of the single tryptophan,tyrosyl and histidyl residues,free amino and carboxyl groups in cobrotoxin suggested that either the intact Trp-29,Tyr-25,His-32,epsilon-amino group of Lys-47or gamma-carboxyl group of Glu-21is essential for full activity of the toxin. Cobrotoxin is a basic protein having six arginine residues at the positions 28, 30, 33, 36, 39and 59in the sequence. In this study,selective and stepwise chemical modification of arginine residues were conducted with a group specific reagent, phenylglyoxal,at varying pH and the degree of modification in relation to the lethal activity and antigenic specificity has been studied in details. (Modified author abstract)