The Primary Sequences and Neuromuscular Effects of Three Neurotoxic Polypeptides from the Venom of Dendroaspis Viridis

Abstract

1 The primary sequences of three neurotoxins from the venom of Dendroaspis viridis have been determined. 2 Two of the toxins (72 amino acids, 5 disulphide bridges) differ only in the oxidation of a tryptophan residue. 3 The third toxin contains 60 amino-acid residues and 4 disulphide bridges. 4 The toxins are homologous with other neurotoxins from venoms of the Proteroglyphae. 5 The long toxins are unique in the substitution of a glutamic acid residue for a previously invariant lysine. 6 All three toxins have been shown to prevent neuromuscular transmission by reducing the sensitivity of the muscle membrane to the transmitter, acetylcholine. 7 The toxins all act reversibly at the neuromuscular junction. 8 The toxins did not block sensory nerve terminals.