Susumu Oi

Purification and substrate specificities of phospholipase A and B of Sclerotinia fungus.

The phospholipase of Sclerotinia fungus was separated by the paperelectrophoresis method into three fractions, of which one component is phospholipase A and the others phospholipase B. These enzymes could be isolated also by the column chromatography using anion exchange resin Duolite A 2 and DEAE cellulose. The former and one of the latter enzymes were obtained in a crystalline form from its solution saturated with ammonium sulfate. The investigation of substrate specificities of these enzymes has shown that the two phospholipase B hydrolyze a commercial soybean lecithin, and one of them can also attack egg-yolk lecithin without addition of any activating lipides.

Mode of Action of the Phospholipase from Sclerotinia Fungus

By using the purified phospholipase A and B of Sclerotinia Libertiana Fcl., enzymic degradation of soy-lecithin was investigated. From the paperchromatography experiments, it was concluded that the phospholipase A specifically hydrolyzes the ester linkage of unsaturated fatty acid of soy-lecithin whereas the phospholipase B hydrolyzes the linkage of saturated acid of soy-lysolecithin. Phospholipase B also could hydrolyze the two fatty acids from the soy-lecithin, however, the hydrolysis rate was rather inhibited by combination with the phospholipase A. Moreover, the phospholipase B activity on soy-lecithin and soy-lysolecithin was found to be increased by the presence of soy-lecithin and soy-lysolecithin in the reaction mixture, and to be inhibited by the addition of Tween 20.