The amino acid sequences of two postsynaptic neurotoxins isolated from Malayan cobra (Naja naja sputatrix) venom.

The complete amino acid sequences of two postsynaptic neurotoxins (toxin-3 and toxin-5) isolated from Malayan cobra (Naja naja sputatrix) venom were determined by direct automated Edman degradation of peptides obtained from digests with various proteases. Toxin-3 and toxin-5 are both short-chain neurotoxins and their amino acid sequences are highly homologous to Naja naja atra and Naja naja philippinensis neurotoxin, respectively. Toxin-3 is unique in possessing aspartic acid (D) as the fifth residue, while all other homologous short-chain neurotoxins have asparagine (N) at the corresponding position.