title: Glycosidase activity in the excretory-secretory products of the liver fluke, Fasciola hepatica.
abstract: Fasciola hepatica secretes proteolytic enzymes and other molecules that are essential for host penetration and migration. This mixture may include enzymes required for the degradation of supramucosal gels, which defend epithelial surfaces against pathogen entry. These contain hydrated mucins that are heavily glycosylated. Excretory-secretory products (ES) from F. hepatica were examined for a range of glycosidase activities, using synthetic 4-methylumbelliferyl glycosides as substrates. The ES product contained at least 8 different glycosidase activities, the most abundant of which were beta-N-acetylhexosaminidase, beta-galactosidase and beta-glucosidase. Alpha-fucosidase, beta-glucuronidase, alpha-galactosidase, alpha-mannosidase and neuraminidase were also present. Beta-N-acetylhexosaminidase and beta-galactosidase were present in multiple isoforms (at least 4), whereas beta-glucosidase appeared to exist as one isoenzyme with a pI < 3.8. All three enzymes had acidic pH optima (4.5-5.0). Ovine small intestinal mucin was degraded by ES at pH 4.5 or 7.0, with or without active cathepsin L, the major protease found in F. hepatica ES. The ability of F. hepatica ES to degrade mucin in the presence or absence of active cathepsin L suggests that cathepsin L is not essential for mucin degradation. The abundance of beta-galactosidase and beta-hexosaminidase in ES supports a role for these enzymes in mucin degradation.
authors.affiliation: Department of Veterinary Physiology and Biochemistry, Faculty of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. jane.irwin@ucd.ie
authors.forename: J A
authors.initials: JA
authors.lastname: Irwin
authors.forename: P E W
authors.initials: PE
authors.lastname: Morrissey
authors.forename: J P
authors.initials: JP
authors.lastname: Ryan
authors.forename: A
authors.initials: A
authors.lastname: Walshe
authors.forename: S M
authors.initials: SM
authors.lastname: O'Neill
authors.forename: S D
authors.initials: SD
authors.lastname: Carrington
authors.forename: E
authors.initials: E
authors.lastname: Matthews
authors.forename: E
authors.initials: E
authors.lastname: Fitzpatrick
authors.forename: G
authors.initials: G
authors.lastname: Mulcahy
authors.forename: A P
authors.initials: AP
authors.lastname: Corfield
authors.forename: J P
authors.initials: JP
authors.lastname: Dalton
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D002847:Chromatography, Agarose; D005210:Fasciola hepatica / Q000201:enzymology*; D005211:Fascioliasis / Q000469:parasitology / Q000662:veterinary*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D015801:Helminth Proteins / Q000378:metabolism*; D006651:Histocytochemistry; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism; D007527:Isoenzymes; D008970:Molecular Weight; D009077:Mucins / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: C030561:4-methylumbelliferyl glycosides; D006027:Glycosides; D015801:Helminth Proteins; D007527:Isoenzymes; D009077:Mucins; D006923:Hymecromone; D006026:Glycoside Hydrolases; D001617:beta-Glucosidase; D001616:beta-Galactosidase; D001619:beta-N-Acetylhexosaminidases