Purine N9-β-D-nucleosides containing 3-amino-3-deoxy-β-D-ribofaranose, 3-amino-2,3-dideoxy-β-D-ribofuranose, and 2-amino-2-deoxy-β-D-ribofuranose as sugar moieties are synthesized by biocatalytic transglycosylation of purine bases and the respective 3′-amino-3′-deoxyuridine, 3′-amino-3′-deoxythymidine and 2′-amino-2′-deoxyuridine as donors of the carbohydrate moiety, and the cells of Escherichia coli as a biocatalyst or glutaraldehyde (GA) treated cells of Escherichia coli as a biocatalyst or a mixture of thymidine (uridine) phosphorylase and purine nucleoside phosphorylase.