Biochemical characterization of a toxin from Indian cobra (Naja naja naja) venom

Abstract

A major toxic component was isolated from the venom of Indian cobra (Naja naja naja) by ammonium sulfate fractional precipitation followed by carboxymethyl cellulose column chromatography and Sephadex gel filtration. This component constituted 2% of the venom and produced a block of neuromuscular transmission in nerve muscle preparations. Three other toxic fractions comprising 3% of the venom were also detected. The major toxic component was homogeneous on starch and polyacrylamide gel electrophoresis and on rechromatography on CM-cellulose. Its molecular weight was approximately 6300. This toxin contained 61 amino acid residues including 8 half-cystine residues whereas alanine, methionine and phenylalanine were totally absent. Its LD₅₀, as determined by i.p. injection in mice, was 0·2 mg per kg body weight. The fraction did not possess any enzymatic, hemolytic or hemagglutinin activities of crude venom but showed a close resemblance to the major neurotoxin of Formosan cobra venom.