title: Regioselectivity in beta-galactosidase-catalyzed transglycosylation for the enzymatic assembly of D-galactosyl-D-mannose.
abstract: The regioselectivity of beta-galactosidase derived from Bacillus circulans ATCC 31382 (beta-1,3-galactosidase) in transgalactosylation reactions using D-mannose as an acceptor was investigated. This D-mannose associated regioselectivity was found to be different from reactions using either GlcNAc or GalNAc as acceptors, not only for beta-1,3-galactosidase but also for beta-galactosidases of different origins. The relative hydrolysis rate of Gal beta-pNP and D-galactosyl-D-mannoses, of various linkages, was also measured in the presence of beta-1,3-galactosidase and was found to correlate well with the ratio of disaccharides formed by transglycosylation. The unexpected regioselectivity using D-mannose can therefore be explained by an anomalous specificity in the hydrolysis reaction. By utilizing the identified characteristics of both regioselectivity and hydrolysis specificity using D-mannose, an efficient method for enzymatic synthesis of beta-1,3-, beta-1,4- and beta-1,6-linked D-galactosyl-D-mannose was subsequently established.
authors.affiliation: Food Science Institute, Meiji Dairies Co., Odawara, Kanagawa 250-0862, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Miyasato
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ajisaka
mesh_terms: D001407:Bacillus / Q000737:chemistry*; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D008358:Mannose / Q000138:chemical synthesis*; D001616:beta-Galactosidase / Q000737:chemistry*
chemical_list: D004187:Disaccharides; C047464:epilactose; D001616:beta-Galactosidase; D008358:Mannose