Enzymatic synthesis of a galactose-containing trehalose analogue disaccharide by Pyrococcus horikoshii trehalose-synthesizing glycosyltransferase: Inhibitory effects on several disaccharidase activities

Pyrococcus horikoshii trehalose-synthesizing glycosyltransferase employed a galactose as an acceptor in the glucosyl transfer reaction with an NDP-Glc donor. The reaction produced a non-reducing transfer product in a yield of more than 30% based on the molar concentration of donor used. The transfer product was purified by paper chromatography and preparative HPLC, and its glycosidic structure was confirmed by 13C nuclear magnetic resonance to be α-d-glucopyranosyl α-d-galactopyranoside. Interestingly, this trehalose analogue disaccharide inhibited the action of several disaccharidases, including a trehalase. The analogue competitively inhibited porcine kidney and rat intestinal trehalases with Ki values of 0.68 and 3.7 mM, respectively. It also competitively inhibited other intestinal disaccharidases such as sucrase, maltase, and isomaltase with respective Ki values of approximately 0.66, 3.0, and 2.1 mM. Accordingly, this trehalose analogue would be a potentially indigestible disaccharide, effectively inhibiting intestinal brush border disaccharidases.