Ghoneim H, Klinkert M Q
Istituto di Biologia Cellulare, Consiglio Nazionale delle Ricerche, Rome, Italy.
Int J Parasitol. 1995 Dec;25(12):1515-9. doi: 10.1016/0020-7519(95)00079-8.
A previously described "major acidic proteinase" of adult Schistosoma mansoni, believed to play a key role in the parasite's metabolism, has been identified as a cathepsin B (Sm31). Purified Sm cathepsin B was not recognized by anti-Sm32 or anti-cathepsin L antibodies. The enzyme hydrolyzes the synthetic protease substrates Z-Arg-Arg-AMC and Z-Phe-Arg-AMC as well as protein substrates. Its pH optimum is 3.0 with serum albumin, 4.0-5.0 with globin and 5.5-6.0 with the synthetic substrates. The enzyme was inactivated by cysteine proteinase inhibitors. Its activity against protein substrates would support the hypothesis that it plays a role in schistosome nutrition.
