title: A direct enzymatic synthesis of beta-D-galactopyranosyl-D-xylopyranosides and their use to evaluate rat intestinal lactase activity in vivo.
abstract: By enzymatic beta-D-galactosylation of D-xylose a mixture of 4-, 3-, and 2-O-beta-D-galactopyranosyl-D-xyloses (1, 4, and 7, respectively) was obtained in 50% isolated yield. Disaccharides 1, 4, and 7 are substrates of intestinal lactase isolated from lamb small intestine with K(m) values of 250.0, 4.5, and 14.0 mM, respectively. The mixture was used to monitor the normal decline in lactase activity in rats that takes place after weaning. The data obtained by this method correlated with the levels of intestinal lactase activity in the same animals after being sacrificed.
authors.affiliation: Instituto de Química Orgánica, CSIC, Madrid, Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: Aragón
authors.forename: F J
authors.initials: FJ
authors.lastname: Cañada
authors.forename: A
authors.initials: A
authors.lastname: Fernández-Mayoralas
authors.forename: R
authors.initials: R
authors.lastname: López
authors.forename: M
authors.initials: M
authors.lastname: Martín-Lomas
authors.forename: D
authors.initials: D
authors.lastname: Villanueva
mesh_terms: D000107:Acetylation; D000818:Animals; D002236:Carbohydrate Conformation; D002849:Chromatography, Gas; D004187:Disaccharides / Q000138:chemical synthesis* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D005690:Galactose / Q000031:analogs & derivatives; D006027:Glycosides / Q000138:chemical synthesis*; D007422:Intestines / Q000201:enzymology; D007700:Kinetics; D043322:Lactase; D009682:Magnetic Resonance Spectroscopy; D009598:Nitrophenylgalactosides / Q000378:metabolism; D051381:Rats; D014994:Xylose / Q000378:metabolism / Q000652:urine; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D004187:Disaccharides; D006027:Glycosides; C010807:xylosides; C055012:2-nitrophenylgalactoside; D009598:Nitrophenylgalactosides; D014994:Xylose; D043322:Lactase; D001616:beta-Galactosidase; D005690:Galactose