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 A2 (PLA2) present in this extract, and this investigation was initiated in order to characterize this enzyme. Phospholipase A2 activity of crude extract was inhibited by both a PLA2-specific inhibitor (pBpb) and the metal ion chelator EDTA. L. obliqua PLA2 was purified by liquid chromatography from the crude bristle extract and had a molecular mass of 15 kDa and a pI of 5.9; its N-terminal sequence showed high homology to a sequence of a putative PLA2 obtained from a cDNA library of L. obliqua bristles, and it is tentatively placed among Group III phospholipases A2. This enzyme was stable at 4 °C, sensitive to higher temperatures, and its maximum catalytic activity was at pH 8.0. L. obliqua PLA2 induced hemolysis only when incubated with exogenous lecithin. Thus, the PLA2 purified herein appears to be responsible for the indirect hemolytic activity of the crude bristle extract.