Snake Venom Toxins. The Amino Acid Sequence of Toxin VII2, a Cytotoxin Homologue from Banded Egyptian Cobra(Na/a haje annulifera)Venom

Abstract

Toxin VII2 comprises 60 amino acid residues and is cross-linked by 4 disulfide bridges. The complete amino acid sequence of this toxin was elucidated. The reduced and S-carboxymethylated toxin was digested with trypsin and chymotrypsin and the peptides were purified by ion-exchange chromatography and chromatography or electrophoresis on paper. The Edman procedure, either through the use of the automatic sequenator or by manual manipulation, was employed to obtain the sequence of the intact toxin and the pure peptides. The chymotryptic digest provided the necessary overlapping peptides which allowed the alignment of tryptic peptides. The amino acid sequence of N. h. annulifera toxin VII2 shows a high degree of homology with cytotoxin VII1 of the same venom.