Purification and pharmacological characterization of a cardiotoxin-like protein from Formosan banded krait (Bungarus multicinctus) venom.

By ion exchange chromatography followed by gel filtration, a polypeptide toxin was purified from Formosan banded krait (Bungarus multicinctus) venom. The toxin had a molecular weight of 7000 +/- 300 and showed an amino acid composition characteristic of cardiotoxin from cobra venom. The i.p. LD50 value of the toxin was 2.5 (1.9-3.2) mg per kg mouse. Pharmacological studies showed that the toxin (10 micrograms/ml) induced contracture in chick and mouse skeletal muscles, depolarized the cell membrane of the mouse diaphragm, arrested the contraction of spontaneously beating atria and the electrically driven ventricle strip of the rat, and caused direct hemolysis of guinea-pig erythrocytes. From these chemical and pharmacological characterizations it was concluded that this toxin has characteristics similar to those of cobra venom cardiotoxins.