Demonstration of carboxyl and thiol protease activities in adultSchistosoma mansoni, Dirofilaria immitis, Angiostrongylus cantonensisandAscaris suum

Abstract

Evidence has been presented showing two kinds of acidic protease activities in adultSchistosoma mansoni, Dirofilaria immitis, Angiostrongylus cantonensisandAscaris suum. A haemoglobinolytic activity without adding any SH-containing compounds was maximal at pH 3.5, 2.5, 30 and 3.5 inS. mansoni, D. immitis, Angiostrongylus cantonensisandAscaris suumrespectively. The inhibitor studies demonstrated that this activity is ascribable to carboxyl protease(s). In the presence of dithiothreitol, activity on Azocoll (azo-dye coupled hide powder) was maximal at pH 4.6, 4.6, 3.5 and 5.6 inS. mansoni, D. immitis, Angiostrongylus cantonensisandAscaris suumrespectively. The effects of inhibitors demonstrated that this activity belongs to the thiol protease class. The intraspecific distribution of the protease activities was studied in some of the nematodes from which the organs could be anatomically separated. The distribution patterns of the haemoglobinolytic and azocollytic activities were quite different inAn. cantonensisand much the same inAs. suum. Based on the present results, acidic haemoglobinolytic activities reported in adultS. mansoniby other authors are thought to be due to carboxyl and thiol protease(s) respectively.