ISOLATION AND PROPERTIES OF A NOVEL PHOSPHOLIPASE-A FROM RAT-BRAIN THAT HYDROLYZES FATTY-ACIDS AT SN-1 AND SN-2 POSITIONS

A Ca2+-independent phospholipase A that releases various fatty acids f rom sn-1 and sn-2 positions was partially purified from rat brain solu ble fraction. The enzyme showed an approximate molecular mass of 300 k Da on gel filtration column chromatography. Its enzymatic properties a re distinct from those of well characterized phospholipase A(2) enzyme s; by using a series of synthetic phosphatidylcholines, the enzyme cle aved oleic, linoleic, and arachidonic acids like phospholipase A(2), a nd released palmitic and stearic acids like phospholipase A(1). Phosph atidylcholine, phosphatidylethanolamine, phosphatidylinositol, and pho sphatidic acid were hydrolysed with almost equal efficiencies by this enzyme. These results indicate that the enzyme isolated is a novel Ca2 +-independent intracellular phospholipase A that might be responsible for production of various fatty acids from membrane phospholipids.