Purification and characterization of a myotoxic phospholipase A2 from Indian cobra (Naja naja naja) venom.

A major phospholipase A2 (NN-XIII-PLA2) which constitutes 20% of the whole Naja naja naja venom was purified to homogeneity on CM-Sephadex C-25 column chromatography. NN-XIII-PLA2 is a basic protein with a mol. wt of 11,200 by SDS-PAGE. This enzyme has low enzymatic activity but is more toxic to mice than the whole venom. The LD50 value (i.p.) of NN-XIII-PLA2 is 2.4 mg/kg body weight (whole venoms LD50 is 2.8 mg/kg body weight). It induces neurotoxic-like signs in experimental animals. It induces myotoxicity when injected i.m. into the thigh muscle of mice and edema when injected into the foot pads of mice. This enzyme has a fluorescence maxima between 310-316 nm which is typical of tyrosine residues.