Thymidine Phosphorylase – Based Enzymatic Synthesis of Modified Nucleosides

Abstract

Modified nucleosides or nucleotides can inhibit various enzymes, and can act both as anticancer or antiviral agents. The chemical synthesis of 5-carboxyuridine esters is complicated. To overcome this, we performed a one-pot reaction using Escherichia coli thymidine phosphorylase (EC 2.4.2.4), which was active towards various 5-carboxyuracil derivatives as well as 5-fluorouracil, for the production of functionalized unnatural uridine nucleosides. Thymidine phosphorylase mediates nucleobase-exchange reaction to convert thymidine or uridine to modified nucleosides possessing a functional group at the 5th position. It was shown that the methyl, ethyl, propyl, isopropyl, butyl, cyclohexyl, cyclooctyl, and prop-2-ynyl esters of 5-carboxyuracil and 5-fluorouracil are substrates of thymidine phosphorylase, thus allowing enzymatic synthesis of modified nucleosides. This research was supported by the Research Council of Lithuania (LMT) grant [SEN-07/2015].