title: Dietary flavonoid and isoflavone glycosides are hydrolysed by the lactase site of lactase phlorizin hydrolase.
abstract: Lactase phlorizin hydrolase (LPH; EC 3.2.1.62) is a membrane-bound, family 1 beta-glycosidase found on the brush border of the mammalian small intestine. LPH, purified from sheep small intestine, was capable of hydrolysing a range of flavonol and isoflavone glycosides. The catalytic efficiency (k(cat)/K(m)) for the hydrolysis of quercetin-4'-glucoside, quercetin-3-glucoside, genistein-7-glucoside and daidzein-7-glucoside was 170, 137, 77 and 14 (mM(-1) s(-1)) respectively. The majority of the activity occurred at the lactase and not phlorizin hydrolase site. The ability of LPH to deglycosylate dietary (iso)flavonoid glycosides suggests a possible role for this enzyme in the metabolism of these biologically active compounds.
authors.affiliation: Diet, Health and Consumer Science Division, Institute of Food Research, Norwich Research Park, Colney, Norwich, UK. andrea.day@bbsrc.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Day
authors.forename: F J
authors.initials: FJ
authors.lastname: Cañada
authors.forename: J C
authors.initials: JC
authors.lastname: Díaz
authors.forename: P A
authors.initials: PA
authors.lastname: Kroon
authors.forename: R
authors.initials: R
authors.lastname: Mclauchlan
authors.forename: C B
authors.initials: CB
authors.lastname: Faulds
authors.forename: G W
authors.initials: GW
authors.lastname: Plumb
authors.forename: M R
authors.initials: MR
authors.lastname: Morgan
authors.forename: G
authors.initials: G
authors.lastname: Williamson
mesh_terms: D000818:Animals; D005419:Flavonoids / Q000378:metabolism*; D044948:Flavonols; D006027:Glycosides / Q000378:metabolism; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000201:enzymology*; D007421:Intestine, Small / Q000201:enzymology; D007529:Isoflavones / Q000378:metabolism*; D007700:Kinetics; D043322:Lactase; D010694:Lactase-Phlorizin Hydrolase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism; D008322:Mammals; D008871:Microvilli / Q000201:enzymology; D010695:Phlorhizin / Q000378:metabolism; D011794:Quercetin / Q000031:analogs & derivatives / Q000378:metabolism; D012756:Sheep; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D044948:Flavonols; D006027:Glycosides; D007529:Isoflavones; C016527:isoquercitrin; D011794:Quercetin; D010695:Phlorhizin; D043322:Lactase; D001616:beta-Galactosidase; D010694:Lactase-Phlorizin Hydrolase; D007785:Lactose; C080613:spiraeoside