title: Characterization of HC58cDNA, a putative cysteine protease from the parasite Haemonchus contortus.
abstract: Because of the complexity of the cathepsin B-like (CBL) family, an information on the biological and biochemical characteristics of individual CBL genes is lacking. In this study, we investigated the degradative effects of the recombinant HC58 protein isolated from Haemonchus contortus parasites on protein substrates over a broad pH range in vitro. This protein, which hydrolyzed the synthetic peptide substrates Z-FR-AMC and Z-RR-AMC, had characteristics of the cysteine protease class of proteins. In the acidic pH range, the isolated protein actively degraded hemoglobin (Hb), the heavy chain of goat immunoglobulin G, and azocasein. By contrast, it degraded fibrinogen in the alkaline pH range. These activities were strongly inhibited in the presence of the cysteine protease inhibitor E-64. While the protein digested Hb, it did not induce the agglutination of erythrocytes from its natural host. These results suggest that the HC58 protein may play a role in the nutrition of this parasite.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Jiangsu 210095, P R China. cimuleke@yahoo.com
authors.forename: Charles I
authors.initials: CI
authors.lastname: Muleke
authors.forename: Yan
authors.initials: Y
authors.lastname: Ruofeng
authors.forename: Xu
authors.initials: X
authors.lastname: Lixin
authors.forename: Sun
authors.initials: S
authors.lastname: Yanming
authors.forename: Li
authors.initials: L
authors.lastname: Xiangrui
mesh_terms: D000818:Animals; D002364:Caseins / Q000378:metabolism; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D015511:Goat Diseases / Q000469:parasitology*; D006041:Goats; D006188:Haemonchiasis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D006386:Hemagglutination Tests / Q000662:veterinary; D006454:Hemoglobins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000378:metabolism; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D018510:RNA, Helminth / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
chemical_list: D002364:Caseins; D015853:Cysteine Proteinase Inhibitors; D018076:DNA, Complementary; D006454:Hemoglobins; D007074:Immunoglobulin G; D018510:RNA, Helminth; D011994:Recombinant Proteins; C026018:azocasein; D002401:Cathepsin B; D007930:Leucine; C024974:E 64