PURIFICATION AND TOXICOLOGICAL IDENTIFICATION OF FRACTION Ⅷ-2 FROM THE VENOM OF OPHIOPHAGUS HANNAH

The Ophiophagus hannah venom has been fractionated by chromatography on CM-Sephadex C-25 into twenty fractious. Fraction Ⅷ-2 was purified by gel filtration on Sephadex G-50, ion-exchange rechromatography on CM-Cellulose 32 and reuse of Sephadex G-50. Homogeneity was proved by three different kinds of polyacrylamide gel electrophoresis. Its molecular weight, calculated from the measurement in SDS-polyacrylamide gel electrophoresis, is 7,827, The isoelectric point is about 7.6 by isoelectric focusing. The LD₅₀ for mice (i p) is 0.155 mg/kg (0.146-0.165 mg/kg).Fraction Ⅷ-2 was shown to block the neuromuscular transmission of chick biventer cervicis muscle and inhibit the acetylcholine response of the muscle after neuromuscular blockade. No effect on the response of the muscle to direct stimulation or to KCI was observed. This indicates that fraction Ⅷ-2 is a postsynaptic neurotoxin, Its blocking action was hardly reversible after repetitive washing in 6 hours.From comparison between fraction Ⅷ-2 and α-Bungarotoxin in the amino acid composition analysis, molecular weight determination, double immunodiffusion, LD₅₀ and the properties of neuromuscular blockade, it is inferred that fraction Ⅷ-2 is a long postsynaptic neurotoxin which is similar to α-Bungarotoxin.