Enzymatic synthesis of a library of β-(1→4) hetero- d-glucose and d-xylose-based oligosaccharides employing cellodextrin phosphorylase Original Research Article

Enzymatic synthesis was attempted of six trisaccharides and 14 tetrasaccharides comprising β-(1→4)-linked d-glucose and d-xylose residues, using cellodextrin phosphorylase (CDP, EC 2.4.1.49) as the enzyme catalyst, with α-d-glucose 1-phosphate (1) or α-d-xylose 1-phosphate (2) as the donor substrates, and cellobiose (3), xylobiose (4), βGlc-(1→4)-Xyl (5), or βXyl-(1→4)-Glc (6) as the acceptor substrates. All enzymatic reactions were performed at pH 7.0 and the products purified by gel-filtration chromatography. We successfully synthesized all six hetero-trisaccharides and 10 of the 14 possible hetero-tetrasaccharides. It was not found possible to synthesize the four tetrasaccharides with a Xyl→Glc sequence at their non-reducing ends employing this method. The stereochemistries of the isolated products were assessed by analysis of their 2D NMR spectra (DQF-COSY, TOCSY, HSQC, HMBC), confirming that all of the glycosidic bonds in the products were β-(1→4) linkages.