Structure-Activity Relationships and Immunochemical Studies on Cobrotoxin
Final rept. 18 Dec 1972-17 Dec 1973
KAOHSIUNG MEDICAL COLL (TAIWAN) DEPT OF BIOCHEMISTRY
Pagination or Media Count:
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-47 or gamma-carboxyl group of Glu-21 is essential for full activity of the toxin. Cobrotoxin is a basic protein having six arginine residues at the positions 28, 30, 33, 36, 39 and 59 in 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.