Arch Biochem Biophys 2019 10 11;674:108106. Epub 2019 Sep 11.
Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland. Electronic address:
In view of previous crystallographic studies, N-hydroxy-dCMP, a slow-binding thymidylate synthase inhibitor apparently caused "uncoupling" of the two thymidylate synthase-catalyzed reactions, including the N-methylenetetrahydrofolate one-carbon group transfer and reduction, suggesting the enzyme's capacity to use tetrahydrofolate as a cofactor reducing the pyrimidine ring C(5) in the absence of the 5-methylene group. Testing the latter interpretation, a possibility was examined of a TS-catalyzed covalent self-modification/self-inactivation with certain pyrimidine deoxynucleotides, including 5-fluoro-dUMP and N-hydroxy-dCMP, that would be promoted by tetrahydrofolate and accompanied with its parallel oxidation to dihydrofolate. Electrophoretic analysis showed mouse recombinant TS protein to form, in the presence of tetrahydrofolate, a covalently bound, electrophoretically separable 5-fluoro-dUMP-thymidylate synthase complex, similar to that produced in the presence of N-methylenetetrahydrofolate. Read More