PURIFICATION OF A PHOSPHATIDIC-ACID-HYDROLYZING PHOSPHOLIPASE A(2) FROM RAT-BRAIN

A phosphatidic-acid-hydrolysing phospholipase A(2) was purified from rat brain and characterized. This phospholipase A(2) was purified by sequential cation, hydrophobic, heparin and gelfiltration chromatography, The purified protein had a mass of similar to 58 kDa as assayed by SDS/PAGE, had a pH optimum of 6.0, and was Ca2+-independent. This enzyme was apparently phosphatidic-acid-selective and had little measurable catalytic activity when phosphatidylcholine, phosphatidylethanolamine or diacylglycerol was used as substrate. On the basis of its physical and catalytic properties, we conclude that this phospholipase A(2) is unique from those previously purified, and we speculate that it may be important for the production of the bioactive lipid lysophosphatidic acid.