Transglycosylation Catalyzed by Almond β-glucosidase and ClonedPichia etchellsiiβ-glucosidase II using Glycosylasparagine Mimetics as Novel Acceptors

The stability of almond ?-glucosidase in five different organic media was evaluated. After 1 hour of incubation at 30�C, 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 ?-D-glucopyranoside as donor and ?-1-N-acetamido-D-glucopyranose, which is a glycosylasparagine mimic, as acceptor was explored under different reaction conditions using almond ?-glucosidase and cloned Pichia etchellsii ?-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 ?-glucosidase II reaction while the latter predominated in the almond enzyme catalyzed reaction. Use of ?-1-N-acetamido-D-mannopyranose and ?-1-N-acetamido-2-acetamido-2-deoxy-D-glucopyranose as acceptors in almond ?-glucosidase catalyzed reactions, however, did not afford any disaccharide products revealing the high acceptor specificity of this enzyme. ? 2004 Taylor & Francis Ltd.