title: Hymenolepis diminuta (Cestoda) liberates an inhibitor of proteolytic enzymes during in vitro incubation.
abstract: Hymenolepis diminuta liberated measurable amounts of 'Lowry-positive material' (LPM) and protein during incubation for 2 h in vitro. When tapeworms were incubated in the presence of bovine trypsin (BT), or when BT was added to the medium after removing the tapeworms, the enzyme's proteolytic activity was inhibited significantly. Centrifugation of the medium at 30,000 g yielded a pellet composed of tegumental elements, but this fraction did not inhibit BT. The 30,000 g supernatant fraction contained a chemical(s) that inhibited the proteolytic enzymes of the rodent host's intestinal contents (IC). The inhibitor(s) was stable following repeated freeze-thaw cycles, heat labile, and not degraded by BT or IC, and it inhibited the amidase activity of BT in a non-competitive manner.
authors.affiliation: Department of Zoology, Ohio State University, Columbus 43210.
authors.forename: P W
authors.initials: PW
authors.lastname: Pappas
authors.forename: G L
authors.initials: GL
authors.lastname: Uglem
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002498:Centrifugation; D003080:Cold Temperature; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D015801:Helminth Proteins / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006926:Hymenolepis / Q000378:metabolism* / Q000648:ultrastructure; D007422:Intestines / Q000201:enzymology*; D008854:Microscopy, Electron; D011480:Protease Inhibitors / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000378:metabolism*
chemical_list: D003470:Culture Media; D015801:Helminth Proteins; D011480:Protease Inhibitors; D014361:Trypsin Inhibitors