Enzymatic Synthesis of Biologically Active 5-Substituted Analogues of 2ʹ-Deoxyuridine by Lactobacillus leichmannii Nucleoside Deoxyribosyltransferase Type II

Abstract

Objective: NDTs and NPs, belong to the class of glycosyltransferases, which can be used to produce biologically active nucleosides by enzymatic transglycosylation under mild conditions, following the principles of ‘green chemistry’. Enzymatic transglycosylation is a stereo- and regiospecific reaction that allows obtaining target nucleosides of high purity, allowing it to compete with chemical methods of synthesis. Methods: In the present work, we used Lactobacillus leichmannii nucleoside deoxyribosyltransferase type II for the synthesis by enzymatic transglycosylation. Reaction media contained 7-methyl-2′-deoxyguanosine as a carbohydrate moiety donor, and corresponding modified pyrimidine heterocyclic bases as acceptors. Results and Discussion: The reaction conditions were 1 : 3 acceptor/donor molar concentration ratio and enzymatic transglycosylation was carried out in 25 mM HEPES buffer (pH 7.4). In the case of 5-CF₃-Ura and 5-Vin-Ura, the rate of formation of the target nucleoside was lower. Due to the broader substrate specificity of NDT II, we obtained 5-CF₃-dUrd, which could not be synthesized using E. coli TP. The yields (conversion) for 5-F-Ura, 5-Cl-Ura and 5-I-Ura were quantitative, 68% for 5-Vin-Ura and 67% for 5-CF₃-Ura. Conclusions: Biologically active 2ʹ-deoxyuridine derivatives in high yields were obtained, three ones currently used in clinical practice in antiviral and antitumour therapy. The selected enzyme-catalyst, initial ratios of molar concentrations of substrates and the selected nucleoside-donor – source of carbohydrate residue – will make it possible to develop environmentally friendly biochemical methods for the preparation of practically important modified nucleosides.