Neurotoxins of Bungarus multicinctus venom purification and partial characterization

Abstract

The purification to homogeneity of 9 neurotoxic components of the venom of B. multicinctus is described. The purified components include .alpha.-bungarotoxin and 2 other .alpha.-type synaptic toxins and .beta.-bungarotoxin and 5 other .beta.-type synaptic toxins. The purified toxins were characterized by electrophoresis, isoelectric focusing, amino acid analysis and N-terminal amino acid determination. The .alpha.-type synaptic neurotoxins constitute a discrete class with MW of 7000-8500, isoelectric points (pI) of 9.0-9.2 and N-terminal isoleucine or methionine. The .beta.-type synaptic neurotoxins constitute a 2nd group with MW of 20,000-22,000 and pI = 8.8-9.7. Fractions 10 through 13 exhibit a chain structure consisting of a 6000-7000 light chain and a 11,000-15,000 heavy chain apparently covalently stabilized by interchain disulfides. Fractions 9A and 14 were single chains of 11,000-14,000 which resemble the sequenced .beta.-type synaptic neurotoxin notexin. All of the .beta.-type synaptic toxins have a single tryptophan and N-terminal aspartic acid or asparagine.