Purification and some properties of two phospholipases and a toxin from the venom of desert cobra (Walterinnesia aegyptia)

An acidic and a basic phospholipase A (PLA) and a toxin have been purified from the venom of W. aegyptia using a TSK G 3000 SW gel filtration column and a Mono Q ion-exchange column. Both phospholipases and the toxin were found to be in a homogeneous state on SDS-PAGE and their purity was verified by isoelectric focusing. The acidic PLA showed higher enzymatic activity and concentration in venom when compared to basic PLA. The acidic and the basic PLA showed 16.5 +/- 0.5 Kd and 14.5 +/- 0.5 Kd molecular weights respectively, while the toxin showed 12.0 +/- 0.5 Kd molecular weights on SDS-PAGE. The isoelectric points for the acidic and basic PLA were at pH 4.5 and 7.8 respectively. The toxin was focused in the basic region at pH 10. Both phospholipases constitute about 20% of the venom protein and were nontoxic. However, only basic PLA when mixed with the toxin reduced the time required by the toxin alone to kill the mice, while the toxin was highly lethal to mice and its LD50 was 0.4 micrograms/g of body weight of mouse. The toxin showed on phospholipase activity.