Synthesis and interaction with thymidylate synthase of 5′-dithiophosphate and 5′-fluorothiophosphate of thymidine

Abstract

Thymidine-5′-fluorothiophosphate, dTMP(S)F, was synthesized by the oxathiaphospholane, and thymidine 5′-dithiophosphate, dTMPS2, by the dithiaphospholane, method. To estimate the role of 5′-phosphate group ionization in binding of pyrimidine nucleotides by thymidylate synthase, dTMP(S)F was studied as an inhibitor of mouse tumour (L1210) enzyme, and its inhibitory properties were compared with those of dTMPS2, a close dTMP analogue. While dTMPS2 proved to be an inhibitor, competitive vs dUMP, with Kiapp = 94 μM, the 5′-fluorothiophosphate congener displayed no activity, indicating that the enzyme requires for binding the presence of a dianionic 5′-phosphate group in a nucleotide.