title: Regioselectivity of the enzymatic transgalactosidation of D- and L-xylose catalysed by beta-galactosidases.
abstract: The regioselectivity of enzymatic transgalactosidation depends on the source of the beta-galactosidase used. When the galactosyl acceptor only contains secondary hydroxyl groups, e.g., D- or L-xylose, it is possible to find an enzyme that catalyses preferentially the synthesis of any of the three regioisomers 4-, 3- and 2-O-beta-D-galactopyranosyl-D-xylose (1, 2 and 3, respectively) or 4-, 3- and 2-O-beta-D-galactopyranosyl-L-xylose (4, 5 and 6, respectively). Enriched mixtures in 1, 2 or 3 were obtained using beta-galactosidases from Escherichia coli, bovine testes or Aspergillus oryzae, respectively, by transgalactosidation reaction of O-nitrophenyl-beta-D-galactopyranoside and D-xylose, and enriched mixtures in 4, 5 or 6 were obtained in a similar way using beta-galactosidases from Aspergillus oryzae, lamb small-intestine (intestinal lactase-phloridzin hydrolase) or Saccharomyces fragilis, respectively, using L-xylose as acceptor.
authors.affiliation: Instituto de Química Orgánica, CSIC, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Montero
authors.forename: J
authors.initials: J
authors.lastname: Alonso
authors.forename: F J
authors.initials: FJ
authors.lastname: Cañada
authors.forename: A
authors.initials: A
authors.lastname: Fernández-Mayoralas
authors.forename: M
authors.initials: M
authors.lastname: Martín-Lomas
mesh_terms: D000818:Animals; D001236:Aspergillus oryzae / Q000201:enzymology; D002236:Carbohydrate Conformation; D004187:Disaccharides / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology; D005690:Galactose / Q000378:metabolism; D005697:Galactosides / Q000138:chemical synthesis*; D006031:Glycosylation; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009598:Nitrophenylgalactosides / Q000378:metabolism; D012440:Saccharomyces / Q000201:enzymology; D014994:Xylose / Q000737:chemistry*; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D004187:Disaccharides; D005697:Galactosides; C055012:2-nitrophenylgalactoside; D009598:Nitrophenylgalactosides; D014994:Xylose; D001616:beta-Galactosidase; D005690:Galactose