Transglycosylation catalyzed by almond β-glucosidase and cloned Pichia etchellsii β-glucosidase II using glycosylasparagine mimetics as novel acceptors

The stability of almond beta-glucosidase in five different organic media was evaluated. After 1 hour of incubation at 30degreesC, the enzyme retained 95, 91, 81, 74 and 56% relative activity in aqueous solutions [30% (v/v)] of dioxane, DMSO, DMF, acetone and acetonitrile, respectively. Transglucosylation involving p -nitrophenyl beta-D-glucopyranoside as donor and beta-1- N -acetamido-D-glucopyranose, which is a glycosylasparagine mimic, as acceptor was explored under different reaction conditions using almond betaglucosidase and cloned Pichia etchellsii beta-glucosidase II. The yield of disaccharides obtained in both reactions turned out to be 3%. Both enzymes catalyzed the formation of (1-->3)- as well as (1-->6)- regioisomeric disaccharides, the former being the major product in cloned beta-glucosidase II reaction while the latter predominated in the almond enzyme catalyzed reaction. Use of beta-1- N -acetamido-D-mannopyranose and beta-1- N -acetamido-2-acetamido-2-deoxy-D-glucopyranose as acceptors in almond beta-glucosidase catalyzed reactions, however, did not afford any disaccharide products revealing the high acceptor specificity of this enzyme.