title: Efficient synthesis and characterization of lactulosucrose by Leuconostoc mesenteroides B-512F dextransucrase.
abstract: This work describes an efficient enzymatic synthesis and NMR structural characterization of the trisaccharide β-D-galactopyranosyl-(1→4)-β-D-fructofuranosyl-(2→1)-α-D-glucopyranoside, also termed as lactulosucrose. This oligosaccharide was formed by the Leuconostoc mesenteroides B-512F dextransucrase-catalyzed transfer of the glucosyl residue from sucrose to the 2-hydroxyl group of the reducing unit of lactulose. The enzymatic reaction was carried out under optimal conditions, i.e., at 30 °C in 20 mM sodium acetate buffer with 0.34 mM CaCl(2) at pH 5.2, and the effect of factors such as reaction time (0-48 h), enzyme charge (0.8, 1.6, and 2.4 U mL(-1)), and sucrose:lactulose concentration ratios (20:40, 30:30, and 40:20, expressed in g/100 mL) on the formation of transfer products were studied. The highest formation in lactulosucrose was attained at 8 and 24-32 h by using 20%:40% and 30%:30% sucrose:lactulose mixtures, respectively, with 1.6 or 2.4 U mL(-1) dextransucrase, leading to lactulosucrose yields of 27-35% in weight respect to the initial amount of lactulose. Furthermore, minor tetra- and pentasaccharide, both probably derived from lactulose, were also detected and quantified. Likewise, the capacity of lactulosucrose to act as D-glucosyl donor once the sucrose was consumed, could explain its decrease from 16 to 24 h when the highest charge of dextransucrase was used. Considering the chemical structure of the synthesized oligosaccharides, lactulosucrose and its derivatives could potentially be excellent candidates for an emerging prebiotic ingredient.
authors.affiliation: Departamento Bioactividad y Análisis de Alimentos, Instituto de Investigación en Ciencias de la Alimentación, CIAL (CSIC-UAM), CEI (UAM+CSIC), c/Nicolás Cabrera 9, 28049 Madrid, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Díez-Municio
authors.forename: Miguel
authors.initials: M
authors.lastname: Herrero
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Jimeno
authors.forename: Agustín
authors.initials: A
authors.lastname: Olano
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Moreno
mesh_terms: D002853:Chromatography, Liquid; D007934:Leuconostoc / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013395:Sucrose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D013395:Sucrose