BIOCHEMICAL-PROPERTIES OF PURIFIED CATHEPSIN-B FROM SCHISTOSOMA-MANSONI

A previously described ''major acidic proteinase'' of adult Schistosom a mansoni, believed to play a key role in the parasite's metabolism, h as been identified as a cathepsin B (Sm31). Purified Sm cathepsin B wa s not recognized by anti-Sm32 or anti-cathepsin L antibodies. The enzy me hydrolyzes the synthetic protease substrates Z-Arg-Arg-AMC and Z-Ph e-Arg-AMC as well as protein substrates. Its pH optimum is 3.0 with se rum albumin, 4.0-5.0 with globin and 5.5-6.0 with the synthetic substr ates. The enzyme was inactivated by cysteine proteinase inhibitors. It s activity against protein substrates would support the hypothesis tha t it plays a role in schistosome nutrition.