Purification of a phospholipase A2 from Lonomia obliqua caterpillar bristle extract

Lonomia obliqua caterpillar bristle extract induces both direct and indirect hemolytic activity on human and rat washed erythrocytes, and provokes intravascular hemolysis in Wistar rats. Indirect hemolytic activity is assumed to be caused by a phospholipase A(2) (PLA(2)) present in this extract, and this investigation was initiated in order to characterize this enzyme. Phospholipase A(2) activity of crude extract was inhibited by both a PLA(2)-specific inhibitor (pBpb) and the metal ion chelator EDTA. L. obliqua PLA(2) was purified by liquid chromatography from the crude bristle extract and had a molecular mass of 15kDa and a pI of 5.9; its N-terminal sequence showed high homology to a sequence of a putative PLA(2) obtained from a cDNA library of L. obliqua bristles, and it is tentatively placed among Group III phospholipases A(2). This enzyme was stable at 4 degrees C, sensitive to higher temperatures, and its maximum catalytic activity was at pH 8.0. L. obliqua PLA(2) induced hemolysis only when incubated with exogenous lecithin. Thus, the PLA(2) purified herein appears to be responsible for the indirect hemolytic activity of the crude bristle extract.