[Activable phospholipase a2 of rat blood platelets].

Rat blood platelet lysate showed high phospholipase A2 activity and contained much less than activating factor much greater than which increased phospholipase A2 activity. The phospholipase A2 and the much less than activating factor much greater than were eluted together in the same first protein fraction obtained by chromatography on a G 100 Sephadex column washed with tris-HCl buffer (pH 7.2). This mixture of proteins can be further fractionated on a Sepharose Blue CL 6B column in 2 protein fractions. The first fraction eluted by tris-HCl buffer (pH 7.2) showed 10 percent of the initial phospholipase activity; the second fraction eluted by NaCl 1 M-tris HCl buffer (pH 7.2) which showed no phospholipase activity, contains activating factor; if both fractions are mixed the initial phospholipase activity is almost totally restored. In conclusion, in rat blood platelets, phospholipase activity originates in a great part from the association of an much less than activable phospholipase much greater than and an much less than activating factor much greater than.