Defining a process operating window for the synthesis of 5-methyluridine by transglycosylation of guanosine and thymine

This paper describes a high yielding coupled enzymatic reaction using Bacillus halodurans purine nucleoside phosphorylase (PNP) and E. coli uridine phosphorylase (UP) for synthesis of 5-methyluridine (5-MU) by transglycosylation. Key parameters such as reaction temperature, pH, reactant loading, reactor configuration and enzyme loading were investigated. A guanosine conversion of 95% and a 5-MU yield of 85% were achieved at 1 l scale, with a productivity of 10 g l−1 h−1.