The purpose of this study was to assess the significance of thymidylate synthetase (dTMP synthetase) inhibition in growth inhibition caused by 5-fluorouracil (FUra). Three fibroblastic mouse cell lines (Sarcoma 180, MMT, L-cells), three human carcinoma cell lines (HeLa, KB, Hep-2), and a human fibroblast line (U-cells) were incubated for 3 hr with varied concentrations of FUra, and the followin...

Perturbations in folate metabolism are associated with risk for colon cancer, although the underlying mechanisms remain to be established. It is not known if the associations between disruptions in folate metabolism and cancer result from altered S-adenosylmethionine (SAM; also known/abbreviated as AdoMet) synthesis and/or deoxythymidylic acid (dTMP) synthesis. Cytoplasmic serine hydroxymethylt...

3'-Azido-3'-deoxythymidine 5'-triphosphate (AZTTP) was an efficient substrate for the human immunodeficiency virus 1 reverse transcriptase. It was incorporated into both homopolymer and defined sequence DNA-primed RNA templates and DNA-primed DNA templates. The substrate and inhibitor kinetics of both AZTTP and dTTP were dependent on the template-primer and reaction conditions used. dTMP was in...

L-nucleoside analogues such as lamivudine are active for treating viral infections. Like D-nucleosides, the biological activity of the L-enantiomers requires their stepwise phosphorylation by cellular or viral kinases to give the triphosphate. The enantioselectivity of NMP kinases has not been thoroughly studied, unlike that of deoxyribonucleoside kinases. We have therefore investigated the cap...

The replication of recombinant multidrug-resistant HIV-1 clones modeled on clinically derived resistant HIV-1 strains from patients receiving long-term combination therapy with zidovudine (AZT) plus 2',3'-dideoxycytidine was found to regain sensitivity to AZT and stavudine (D4T) as a consequence of a pharmacologically induced decrease in de novo dTMP synthesis. The host-cell system used was phy...

The crystal structures of Escherichia coli thymidylate kinase (TmpK) in complex with P1-(5'-adenosyl)-P5-(5'-thymidyl)pentaphosphate and P1-(5'-adenosyl)P5-[5'-(3'-azido-3'-deoxythymidine)] pentaphosphate have been solved to 2.0-A and 2.2-A resolution, respectively. The overall structure of the bacterial TmpK is very similar to that of yeast TmpK. In contrast to the human and yeast TmpKs, which...

5-Fluoro-2'-deoxyuridine (FUdR) was found to be highly effective in inducing the heritable fragile site on Xq28 associated with mental retardation. Lymphocytes from two affected males manifested the fragile site in 30 to 40% of the mitoses when grown in the presence of FUdR. This observation suggests that depletion of the dTMP pool via thymidylate synthetase inhibition is responsible for the ex...

Background: Gene 1.7 of bacteriophagephage T7 encodes a nucleotide kinase Results: Gp1.7 dodecamers catalyze the reversible dTMP and dGMP kinase reactions Conclusion: Gp1.7 is a unique nucleotide kinase that does not require a divalent metal ion Significance: The unique nucleotide kinase of bacteriophage T7 supplies dTDP and dGDP for conversion to the nucleoside 5’-triphosphate and recycles the...

Erythrocytes from a patient with classical pyrimidine nucleotidase (PyN) deficiency had less than 10% residual PyN activity with uridine 5'-monophosphate (UMP) or cytidine 5'-monophosphate (CMP) as substrate, but exhibited brisk nucleotidase activity with thymidine 5'-monophosphate (dTMP). This strongly suggests the existence of separate enzymes or isozymes of PyN in normal human erythrocytes--...