title: Regioselective synthesis of p-nitrophenyl glycosides of beta-D-galactopyranosyl-disaccharides by transglycosylation with beta-D-galactosidases.
abstract: The beta-D-galactosidase from porcine liver induced regiospecific transglycosylation of beta-D-galactose from beta-D-Gal-OC6H4NO2-o to OH-6 of, respectively, p-nitrophenyl glycoside acceptors of Gal, GlcNAc and GalNAc to afford beta-Gal-(1-->6)-alpha-Gal-OC6H4NO2-p, beta-Gal-(1--> 6)-beta-Gal-OC6H4NO2-p, beta-Gal-(1-->6)-alpha-GalNAc-OC6H4NO2-p, beta-Gal-(1-->6)-beta-GalNAc-OC6H4NO2-p, beta-Gal-(1-->6)-alpha-GlcNAc-OC6H4NO2-p, and beta-Gal-(1-->6)-beta-GlcNAc-OC6H4NO2-p. The enzyme showed much higher transglycosylation activity for the alpha-glycoside acceptors than the corresponding beta-glycoside acceptors. The regioselectivity of the beta-D-galactosidase from Bacillus circulans ATCC 31382 greatly depended on the nature of the acceptor. When alpha-D-GalNAc-OC6H4NO2-p and alpha-D-GlcNAc-OC6H4NO2-p were used as acceptors, the enzyme showed high potency for regioselective synthesis of beta-Gal-(1-->3)-alpha-GalNAc-OC6H4NO2-p and beta-Gal-(1-->3)-alpha-GlcNAc-OC6H4NO2-p in high respective yields of 75.9 and 79.3% based on the acceptors added. However, replacement of beta-D-Gal-OC6H4NO2-p by beta-D-GalNAc-OC6H4NO2-p did change the direction of galactosylation. The enzyme formed regioselectively beta-Gal-(1-->6)-beta-Gal-OC6H4NO2-p with (beta-Gal-1-->(6-beta-Gal-1-->)n6-beta-Gal-OC6H4NO2-p, n = 1-4). No beta-(1-->3)-linked product was detected during the reaction. Use of the two readily available beta-D-galactosidases facilitates the preparation of (1-->3)- and (1-->6)-linked disaccharide glycosides of beta-D-Gal-GalNAc and beta-D-Gal-GlcNAc.
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, Ohya, Japan.
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.forename: R
authors.initials: R
authors.lastname: Yoshino
authors.forename: T
authors.initials: T
authors.lastname: Murata
authors.forename: K
authors.initials: K
authors.lastname: Ajisaka
authors.forename: T
authors.initials: T
authors.lastname: Usui
mesh_terms: D000818:Animals; D002852:Chromatography, Ion Exchange; D004187:Disaccharides / Q000138:chemical synthesis*; D006027:Glycosides / Q000138:chemical synthesis*; D006031:Glycosylation; D006868:Hydrolysis; D008099:Liver / Q000201:enzymology; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D013552:Swine; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D004187:Disaccharides; D006027:Glycosides; D001616:beta-Galactosidase