PROTEOLYTIC ACTIVITIES OF COBRA VENOMS BASED ON INACTIVATION OF ALPHA-2-MACROGLOBULIN

The venoms of various cobra species showed a wide range of abilities to cleave hide powder azure, with Naja naja kaouthia and Ophiophagus hannah venoms showing the lowest activities and Naja nivea venom showing the greatest activity on this dye-linked substrate. The activities of the venoms on hide powder did not completely correlate with their ability to inactivate the α2-macroglobulin of human serum. Incubation of 4-5 μg of Naja nigricollis venom per μl of serum for 30 min caused loss of 95% of the α2-macroglobulin activity of the serum. The inactivation was rapid, reaching 80% inactivation 5 min after mixing. This loss of α2-macroglobulin activity was used to quantitate the weak proteolytic activity of N. nigricollis venom and a partially purified sample of the major fibrinogenolytic proteinase of the venom. The inactivation of α2-macroglobulin was also used to compare the proteinase activities of venoms from seven species or subspecies of cobra. Based on α2-macroglobulin inactivation, N. nigricollis had the highest proteinase activity among the tested venoms. The measurement of α2-macroglobulin inactivation should provide a useful alternative to hide powder digestion for demonstration of weak proteolytic activities in venoms. © 1984.