106. Gram-Scale Enzymatic Synthesis of 2ʹ-Deoxyribonucleoside Analogues Using Nucleoside Transglycosylase-2

Nucleosides are pervasive building blocks that are found throughout nature and used extensively in medicinal chemistry and biotechnology. However, the preparation of base-modified analogues using conventional synthetic methodology poses challenges in scale-up and purification. In this work, an integrated approach, involving structural analysis, screening and reaction optimisation, was established for the preparation of 2'-deoxyribonucleoside analogues catalyzed by the Type II nucleoside 2'-deoxyribosyltransferase from Lactobacillus leichmannii (LlNDT-2). Structural analysis, in combination with substrate profiling, identified the constraints on pyrimidine and purine acceptor bases by LlNDT2. A solvent screen identifies pure water as a suitable solvent for the preparation of high value purine and pyrimidine 2'-deoxyribonucleoside analogues on a gram scale under optimised reaction conditions. This approach provides the basis to establish a convergent, step-efficient chemoenzymatic platform for the preparation of high value 2'-deoxyribonucleosides.