Regioselective O-glucosylation by sucrose phosphorylase: a promising route for functional diversification of a range of 1,2-propanediols.
1,2-Propanediol and 3-aryloxy/alkyloxy derivatives thereof are bulk commodities produced directly from glycerol. Glycosylation is a promising route for their functional diversification into useful fine chemicals. Regioselective glucosylation of the secondary hydroxyl in different 1,2-propanediols was achieved by a sucrose phosphorylase-catalyzed transfer reaction where sucrose is the substrate and 2-O-alpha-d-glucopyranosyl products are exclusively obtained. Systematic investigation for optimization of the biocatalytic synthesis included prevention of sucrose hydrolysis, which occurs in the process as a side reaction of the phosphorylase. In addition to 'nonproductive' depletion of donor substrate, the hydrolysis also resulted in formation of maltose and kojibiose (up to 45%) due to secondary enzymatic glucosylation of the glucose thus produced. Using 3-ethoxy-1,2-propanediol as the acceptor substrate (1.0M), the desired transfer product was obtained in about 65% yield when employing a moderate (1.5-fold) excess of sucrose donor. Loss of the glucosyl substrate to 'glucobiose' by-products was minimal (<7.5%) under these conditions. The reactivity of other acceptors decreased in the order, 3-methoxy-1,2-propanediol>1,2-propanediol>3-allyloxy-1,2-propanediol>3-(o-methoxyphenoxy)-1,2-propanediol>3-tert-butoxy-1,2-propanediol. Glucosylated 1,2-propanediols were not detectably hydrolyzed by sucrose phosphorylase so that their synthesis by transglucosylation occurred simply under quasi-equilibrium reaction conditions.
Luley-Goedl
Christiane
C
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12/1, A-8010 Graz, Austria.
Sawangwan
Thornthan
T
Brecker
Lothar
L
Wildberger
Patricia
P
Nidetzky
Bernd
B
D055162:Biocatalysis; D005964:Glucosyltransferases / Q000378:metabolism*; D006031:Glycosylation; D015394:Molecular Structure; D019946:Propylene Glycol / Q000737:chemistry* / Q000378:metabolism*; D013237:Stereoisomerism
D019946:Propylene Glycol; D005964:Glucosyltransferases; C025901:sucrose phosphorylase