Some properties and the complete primary structures of two reduced and S-carboxymethylated polypeptides (S5C1 and S5C10) from Dendroaspis jamesoni kaimosae (Jameson's mamba) venom.

Two polypeptides (protein S5C1 and toxin S5C10) were purified from Dendroaspis jamesoni kaimosae venom. Whereas protein S5C1 comprises 61 amino acid residues, toxin S5C10 contains 58 and they each comprise four disulphide bridges. The complete primary structures of the two polypeptides have been elucidated. The sequences of protein S5C1 and toxin S5C10 are structurally homologous to the short neurotoxins Type I, but they are much less toxic. In toxin S5C10 one of the functionally invariant amino acid residues, lysine 26, of the Type I neurotoxin has been replaced by a serine. In contrast protein S5C1 has the feature that it contains ten or eleven structurally invariant amino acids and apparently only one of the five functionally invariant residues.