Purified phospholipase A2 from sheep erythrocyte membrane. Preferential hydrolysis according to polar groups and 2-acyl chains.

Hydrolysis of natural phospholipids by pure erythrocyte membrane phospholipase A2 was compared to the reaction catalyzed by the soluble pancreatic enzyme. Fatty acids liberated during both types of reaction were quantitatively analyzed by gas liquid chromatography. We confirm for the pancreatic enzyme lack of specificity with respect to the sn-2 acyl chain of the phospholipids and preference for negatively charged polar head groups. Conversely, the membranous enzyme preferentially attacks uncharged phospholipids and within one class of phospholipid preferentially splits long chain unsaturated fatty acids in the sn-2 position. The significance of such differences between pancreatic and sheep erythrocyte enzyme is discussed in relation to the possible physiological role of the latter enzyme.