Snake Venom Toxins

Abstract

Abstract Three toxins, designated toxins α, β, and δ, have been isolated from the venom of the South African Cape cobra (Naja nivea) by ion exchange chromatography on Amberlite CG-50, and have been further purified by chromatography on carboxymethylcellulose and gel filtration on Sephadex G-50. The toxins are essentially homogeneous by free boundary electrophoresis and amino acid analyses. Toxins α and β have electrophoretic mobilities (ascending) of 3.58 x 10-5 and 5.95 x 10-5 at pH 8.4 and 5.34 x 10-5 and 9.49 x 10-5 cm2 s-1 volt-1 at pH 5.0, respectively. The formula weights of these three toxins are 7897, 6973, and 6834, respectively. Toxin α consists of 71 amino acid residues and is cross-linked by five disulfide bridges, while toxins β and δ contain 61 amino acid residues with four disulfide bridges each. Toxin α is immunochemically distinct from toxins β and δ while the latter two toxins are immunochemically related. Toxin δ was found to have the same amino acid sequence as toxin α from Naja haje haje venom.