Highly regioselective glucosylation of 2′-deoxynucleosides by using the crude β-glycosidase from bovine liver

An enzymatic regioselective approach for the glucosylation of a series of 2′-deoxynucleosides was described by using the crude β-glycosidase from bovine liver that is less expensive and can be simply prepared in a standard organic laboratory. With the glucosylation of 2′-deoxyuridine as a model reaction, the effects of several key factors on the enzymatic reaction were examined. The optimum enzyme dosage, buffer pH and temperature were 0.05 U/ml, 9.5 and 42 °C, respectively. The presence of alkali β-glycosidase as the main active component in the crude enzyme extract might account for the high glucosylation activity at pH 9.5. In addition, the desired 5′-O-glucosylated derivatives of 2′-deoxynucleosides were synthesized with the yields of 22–72% and exclusive 5′-regioselectivities (>99%).