Snake venoms. The amino-acid sequence of polypeptide DE-1 from Ophiophagus hannah (King cobra) venom.

A major polypeptide (DE-1) was purified from King cobra venom by ion-exchange chromatography on CM-cellulose and also DEAE-cellulose and by gel filtration on Sephadex G-50. DE-1 comprises 60 amino acid residues and is cross-linked by four intrachain disulphide bridges. The complete primary structure of the polypeptide has been elucidated. The properties of DE-1 were compared with those of the short neurotoxin and the cytotoxin groups and of the angusticeps types. The sequence and some of the invariant residues of DE-1 resemble the short neurotoxin group and to some degree also the cytotoxin group, but it is a nontoxic (LD50 greater than 250 microgram/g of mouse) polypeptide.