Abstract: A biocatalytic process for producing active pharmaceutical ingredients (APIs) or intermediates thereof, wherein those APIs or their intermediates are nucleoside analogues (NAs) of formula I and wherein said NAs are active as pharmaceutically relevant antivirals and anticancer medicaments, intermediates or prodrugs thereof.

Abstract: A recombinant expression vector comprising: a) the sequence encoding a purine nucleoside phosphorylase (PNPase, E. C. 2.4.2.1), b) the sequence encoding a uridine phosphorylase (UPase, E. C. 2.4.2.3), c) or both; each of the sequences operably linked to one or more control sequences that direct the production of said phosphorylases in a suitable expression host; said sequences originating from the Archaea Thermoprotei class, characterized in that the PNPase is from Sulfolobus solfataricus (SEQ ID NO. 7) and the UPase is from Aeropyrum pernix (SEQ ID NO. 8). In addition, the present invention relates to A transglycosylation method between a sugar-donating nucleoside and an acceptor base in the presence of phosphate ions, characterized in that said method comprises the use of a uridine phosphorylase (UPase) of Aeropyrum pernix (NC_000854.2), a purine nucleoside phosphorylase (PNpase) of Sulfolobus solfataricus (NC_002754.1), or a combination thereof.

Abstract: The present invention relates to a recombinant expression vector comprising: a) the sequence encoding a purine nucleoside phosphorylase (PNPase, E. C. 2.4.2.1), b) the sequence encoding a uridine phosphorylase (UPase, E. C. 2.4.2.3), c) or both; each of the sequences operably linked to one or more control sequences that direct the production of said phosphorylases in a suitable expression host; said sequences originating from the Archaea Thermoprotei class, characterized in that the PNPase is from Sulfolobus solfataricus (SEQ ID NO. 7) and the UPase is from Aeropyrum pernix (SEQ ID NO. 8). In addition, the present invention relates to A transglycosylation method between a sugar-donating nucleoside and an acceptor base in the presence of phosphate ions, characterised in that said method comprises the use of a uridine phosphorylase (UPase) of Aeropyrum pernix (NC_000854.2), a purine nucleoside phosphorylase (PN-Pase) of Sulfolobus solfataricus (NC_002754.1), or a combination thereof.