title: Characterization of proteolytic enzymes from larval and adult Nippostrongylus brasiliensis.
abstract: Proteases from infective larval (L3) and adult stages of Nippostrongylus brasiliensis were investigated with a combination of techniques involving gelatin degradation and cleavage of fluorogenic substrates. Analysis of L3 excretory-secretory (ES) products revealed enzymes of Mr 51, 58, 79, approximately 150 and approximately 250 kDa. Inhibition profiles indicate that the major 51 kDa protease is a metallo-enzyme. Significantly, little activity was present in larval somatic extracts, suggesting the synthesis of zymogens or precursor forms prior to secretion. Adult ES contained a distinct enzyme, of 50 kDa, and a number of other proteases were detected in somatic extracts of this stage, ranging from 51 to greater than 300 kDa. The largest of these adult somatic enzymes is also a putative metallo-protease. While nearly all enzymes from both L3 and adult are heat labile, incubation at 100 degrees C generated a previously unobserved activity at 20 kDa. Furthermore, a protease of similar size may be found in uninfected rat intestinal tissue, suggesting specific uptake of a host-associated enzyme by the parasite in the form of an inactive, heat-labile complex.
authors.affiliation: Department of Biology, Imperial College of Science, Technology and Medicine, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Healer
authors.forename: F
authors.initials: F
authors.lastname: Ashall
authors.forename: R M
authors.initials: RM
authors.lastname: Maizels
mesh_terms: D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000201:enzymology; D008970:Molecular Weight; D009559:Nippostrongylus / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010450:Endopeptidases