1. Rat thymus cells were incubated in homologous serum (10%) and medium 199. The effects of various quantities of thymidine or deoxycytidine (0-30mum) on the radioactive labelling of cells with the corresponding radioactive deoxynucleoside were examined. From plots of the reciprocal of the radioactivity incorporated against the total deoxynucleoside concentration (;isotope-dilution plots'), val...

Thymidine is an important precursor in the production of various antiviral drugs, including azidothymidine for the treatment of AIDS. Since thymidine-containing nucleotides are synthesized only by the de novo pathway during DNA synthesis, it is not easy to produce a large amount of thymidine biologically. In order to develop a host strain to produce thymidine, thymidine phosphorylase, thymidine...

1. Extracts of Landschutz ascites-tumour cells have been fractionated by treatment with acid, alumina C(gamma) gel and Sephadex G-100 to yield purified preparations of thymidine phosphokinase, thymidine 5'-monophosphate phosphokinase and thymidine 5'-diphosphate phosphokinase. 2. These results clearly demonstrate the existence in Landschutz ascites tumour of three phosphokinases each of which c...

The amount of thymidine-H(3) converted to thymidine-H(3) monophosphate in 30 min formed the basis for assays of thymidine kinase in cell extracts from Tetrahymena pyriformis. The optimal concentration of adenosine triphosphate is lower than that required by other cell types. Thymidine triphosphate does not exercise any feedback control of the enzyme. Other deoxyprimidine nucleotides were tested...

A mutant of Escherichia coli lacking the catabolic enzyme thymidine phosphorylase readily incorporates exogenous thymidine into deoxyribonucleic acid (DNA) even when provided at concentrations as low as 0.2 mug/ml. Incorporation by this prototrophic strain occurs specifically into DNA, since, with radioactively labeled thymidine, (i) more than 98% is incorporated into alkali-stable material, (i...

Thymidine infusions (75 g/sq m/24 hr) were administered to 12 cancer patients as part of a Phase I study. Thymidine and thymine measurements, by high-pressure liquid chromatography, were made on plasma and urine from eight of these patients. Only the pharmacokinetic aspects of these studies are reported in this paper. Millimolar thymidine and thymine concentrations were achieved in all patients...