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Hymenolepis diminuta (Cestoda) liberates an inhibitor of proteolytic enzymes during in vitro incubation

Published online by Cambridge University Press:  06 April 2009

P. W. Pappas
Affiliation:
Department of Zoology, The Ohio State University, Columbus, OH 43210, USA
G. L. Uglem
Affiliation:
School of Biological Sciences, University of Kentucky, Lexington, KY 40506, USA

Summary

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.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1990

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