ISOLATION AND CHARACTERIZATION OF A TOXIC PHOSPHOLIPASE-A(2) FROM THEVENOM OF THE TAIWAN HABU (TRIMERESURUS-MUCROSQUAMATUS)

A toxic phospholipase A2 (PLA2) was isolated from Taiwan-habu-snake (T rimeresurus mucrosquamatus) venom by sequential chromatographies on CM -52, Sephadex G-75 and S-Sepharose columns. This basic PLA2 has a sing le polypeptide with an estimated M(r) of 15000. The PLA2 activity was Ca2+-dependent and inactivated by p-bromophenacyl bromide and its spec ific antibody. The toxic PLA2-induced myotoxic and direct haemolytic e ffects as well as respiratory distress in mice with an intraperitoneal LD50 of 1.17 mug/g body weight. The histological examination showed i t caused haemorrhage and congestion in the viscera of mice. It was als o cytotoxic to myeloma cells (NS-1), baby-hamster-kidney (BHK) cells a nd human umbilical endothelial cells. By neutralization experiments wi th a specific antibody against toxic PLA2, it was found that the enzym ic activity of toxic PLA2 is essential for its myotoxicity, but it is not the only factor responsible for the lethal toxicity.