The action of cobra venom phospholipase A2 isoenzymes towards intact human erythrocytes.

1. Cobra venom phospholipase A2 from three different sources has been fractionated into different isoenzymes by DEAE ion-exchange chromatography. 2. Treatment of intact human erythrocytes with the various isoenzymes revealed significant differences in the degree of phospatidylcholine hydrolysis in those cells. 3. It is argued that the plateaus observed in dose-response curves for such treatments may be caused by an increase in lateral surface presure within the outer half of the membrane due to the production of free fatty acids and lyso-compounds.