Reaction of the main proteolytic fraction of Schistosoma mansoni cercarial enzymes with synthetic substrates and inhibitors of proteolytic enzymes

The purified proteolytic fraction of Schistosoma mansoni cercarial enzymes (PCF) was inhibited by Diisopropylphosphofluoridate (DFP). Its esterolytic activity was not affected by either of two specific active center reagents of proteolytic enzymes: (1) 1-chloro-3-tosylamido-7-ammo-2-heptanone (trypsin) and (2) l-1-tosylamido-2-phenylethyl chloromethyl ketone (chymotrypsin). Furthermore, PCF did not destroy the biological activity of bradykinin on the isolated guinea pig ileum, nor did it release bradykinin from purified dog plasma bradykininogen.