title: Transglycosylation by Streptococcus mutans GS-5 glucosyltransferase-D: acceptor specificity and engineering of reaction conditions.
abstract: The acceptor specificity of Streptococcus mutans GS-5 glucosyltransferase-D (GTF-D) was studied, particular the specificity toward non-saccharide compounds. Dihydroxy aromatic compounds like catechol, 4-methylcatechol, and 3-methoxycatechol were glycosylated by GTF-D with a high efficiency. Transglycosylation yields were 65%, 50%, and 75%, respectively, using 40 mM acceptor and 200 mM sucrose as glucosyl donor. 3-Methoxylcatchol was also glycosylated, though at a significantly lower rate. A number of other aromatic compounds such as phenol, 2-hydroxybenzaldehyde, 1,3-dihydroxybenzene, and 1, 2-phenylethanediol were not glycosylated by GTF-D. Consequently GTF-D aromatic acceptors appear to require two adjacent aromatic hydroxyl groups. In order to facilitate the transglycosylation of less water-soluble acceptors the use of various water miscible organic solvents (cosolvents) was studied. The flavonoid catechin was used as a model acceptor. Bis-2-methoxyethyl ether (MEE) was selected as a useful cosolvent. In the presence of 15% (v/v) MEE the specific catechin transglucosylation activity was increased 4-fold due to a 12-fold increase in catechin solubility. MEE (10-30% v/v) could also be used to allow the transglycosylation of catechol, 4-methylcatechol, and 3-methoxycatechol at concentrations (200 mM) otherwise inhibiting GTF-D transglycosylation activity.
authors.affiliation: Division of Industrial Microbiology, Department of Food Technology and Nutritional Sciences, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: G H
authors.initials: GH
authors.lastname: Meulenbeld
authors.forename: S
authors.initials: S
authors.lastname: Hartmans
mesh_terms: D001709:Biotechnology / Q000379:methods*; D002392:Catechin / Q000737:chemistry / Q000378:metabolism*; D005026:Ethylene Glycols / Q000737:chemistry; D005936:Glucans / Q000378:metabolism; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006031:Glycosylation; D008738:Methyl Ethers / Q000737:chemistry; D009154:Mutation; D012997:Solvents; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D005026:Ethylene Glycols; D005936:Glucans; D008738:Methyl Ethers; D012997:Solvents; D002392:Catechin; D005964:Glucosyltransferases; C113848:glucosyltransferase D; C007391:diglyme