Cathepsin B-like activity predominates over cathepsin L-like activity in adult Schistosoma mansoni and S-japonicum

Both cathepsin B-like and cathepsin L-like endopeptidase activities have been described in schistosomes. bur their relative contribution to proteinolysis remains controversial. In an attempt to clarify which type of activity predominates, the selective mammalian cathepsin B inhibitor CA-074 was tested under standardized assay conditions with different preparations from Schistosoma mansoni and S. japonicum. CA-074 (0.93 mu M) inhibited at least 92% and 80% of proteinolytic activity, respectively, for these species: completely inhibited bovine-spleen cathepsin B activity: but showed only marginal inhibition (4%) of rat-liver cathepsin L activity. We discuss the results with respect to previous studies and conclude that schistosome cathepsin B-like. not L-like, activity predominates.