ENZYMATIC GLUCOSYLATION OF HYDROPHOBIC ALCOHOLS IN ORGANIC MEDIUM BY THE REVERSE HYDROLYSIS REACTION USING ALMOND-BETA-D-GLUCOSIDASE

Alkyl beta-D-glucosides were synthesized from D-glucose and alcohols b y reverse hydrolysis using the commercially available almond beta-D-gl ucosidase in 9:1 (v/v) acetonitrile-water medium. The main characteris tics of this enzyme-catalyzed glucosylation were established by using 2-hydroxybenzyl alcohol. The reaction is entirely regio- and stereosel ective. The solvent plays a fundamental role because, by decreasing th e water concentration in the medium, the shift of the reaction equilib rium toward synthesis is realized without using an excessive amount of alcohol. Nevertheless, a minimum amount of water is necessary to main tain the enzyme activity. In contrast to the use of the enzyme in aque ous medium, the pH of the added water in acetonitrile did not influenc e the synthesis. Using this procedure, we have conducted systematic gl ucosylation of numerous alcohols and we have investigated enzyme speci ficity and alcohol reactivity. The enzyme has a pronounced affinity fo r the alcohols containing a phenyl group, and enantioselectivity for t he aglycon is obtained with 1-phenylethyl alcohol. Moreover, by using almond beta-D-glucosidase it was also possible to synthesize alkyl bet a-D-galactosides. (C) 1995 John Wiley and Sons, Inc.