The primary structure of toxin C from the venom of the Indian cobra (Naja naja).

Abstract

The primary structure of toxin C, a neurotoxin isolated from Indian cobra (Naja naja) venom, was determined. Toxin C is a highly toxic polypeptide consisting of 71 amino acid residues (molecular weight 7800) crosslinked by five disulfide bridges. A high degree of homology is observed among the long-chain neurotoxins. Toxin C differs from toxin A only in having -Ala-28 and -Lys-49 in place of -Gly-28 and -Arg-49, and from toxin B in having -Ala-28, -Ile-32 and -Lys-49 in place of -Gly-28, -Ser-32 and -Arg-49 residues. The amino acid sequence of toxin C is the same as that of Naja naja siamensis neurotoxin 3.