Enzymatic synthesis of ribo- and 2′-deoxyribonucleosides from glycofuranosyl phosphates: An approach to facilitate isotopic labeling

Abstract Milligram quantities of α-D-ribofuranosyl 1-phosphate (sodium salt) (αR1P) were prepared by the phosphorolysis of inosine, catalyzed by purine nucleoside phosphorylase (PNPase). The αR1P was isolated by chromatography in >95% purity and characterized by 1 H and 13 C NMR spectroscopy. Aqueous solutions of αR1P were stable at pH 6.4 and 4 °C for several months. The isolated αR1P was N -glycosylated with different nitrogen bases (adenine, guanine and uracil) using PNPase or uridine phosphorylase (UPase) to give the corresponding ribonucleosides in high yield based on the glycosyl phosphate. This methodology is attractive for the preparation of stable isotopically labeled ribo- and 2′-deoxyribonucleosides because of the ease of product purification and convenient use and recycling of nitrogen bases. The approach eliminates the need for separate reactions to prepare individual furanose-labeled ribonucleosides, since only one ribonucleoside (inosine) needs to be labeled, if desired, in the furanose ring, the latter achieved by a high-yield chemical N -glycosylation. 2′-Deoxyribonucleosides were prepared from 2′-deoxyinosine using the same methodology with minor modifications.