Synthesis of Polysaccharides by Using Enzyme Catalyst

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The in vitro synthesis of cellulose via a nonbiosynthetic path has been achieved for the first time by condensation of beta-D-cellobiosyl fluoride as substrate for cellulase in a mixed solvent of acetonitrile/acetate buffer (pH 5,5:1)(enzymatic polymerization). Under reaction condition of a higher substrate concentration or higher acetonitrile concentration, cellooligosaccharides were produced predominantly. The present method of using a glycosyl fluoride as substrate for a hydrolytic enzyme in an organic/water mixed solvent has successfully been applied to synthesis of maltooligosaccharides and unnatural oligosaccharides.A new methodology for regio and stereoselective synthesis of cellooligosaccharide derivatives has been developed by utilizing the following two enzymatic reactions : A cellulase-catalyzed stereoselective lactosylation of an alkyl cellobioside giving rise to a new oligosaccharide having a D-galactose unit at the nonreducing end and a beta-galactosidase-catalyzed regioselective cleavage of the terminal D-galactose unit of the product.