Observations on a Venom Neutralizing Fraction Isolated from Serum of the Northern Copperhead, Agkistrodon contortrix mokasen

Venom neutralizing capacity of serum from the northern copperhead, Agkistrodon contortrix mokasen, was studied. Crude serum neutralized the hemorrhagic, proteolytic, and lethal activity of A. c. mokasen venom. The serum neutralized up to 2.5 LD50of A. c. mokasen venom and up to 5 LD50of A. piscivorus conanti venom. The serum was antihemorrhagic and a potent inhibitor of venom proteases and trypsin. A fraction was isolated from A. c. mokasen serum by DEAE-Affi-Gel Blue chromatography and Superose-12 (molecular sieve) fast protein liquid chromatography with recycling. This fraction contained two major proteins with apparent molecular weights of 62 kD and 79 kD. The fraction had a pl of 4.6-4.7, displayed anodal migration in horizontal electrophoresis, and exhibited the venom neutralization capacity of the crude serum but did not inhibit venom proteases or trypsin. In amounts of only 16.5 μg, it protected against hemorrhage induced by up to 100 μg of A. c. mokasen venom.