mercaptopurine and azauracil

We measured the concentration of nucleoside triphosphates and inorganic pyrophosphate in Escherichia coli in conditions where nucleotide synthesis or nucleic acid synthesis was inhibited. The inhibitors that brought about an accumulation of some of the four ribonucleoside triphosphates also increased the pyrophosphate level. In a pyrimidine auxotrophic strain uracil starvation led to simultaneous accumulation of ATP and pyrophosphate, and they both rapidly returned to normal level when starvation was relieved. These results indicate the possible involvement of pyrophosphate in the reactions leading to the accumulation of nucleoside triphosphates.

Topics: Adenosine Triphosphate; Chromatography, High Pressure Liquid; Diphosphates; Escherichia coli; Fluorouracil; Hydroxyurea; Luminescent Measurements; Mercaptopurine; Mutation; Ribonucleotides; Species Specificity; Uracil

1. The inhibition of NAD-linked 3alpha-hydroxy steroid dehydrogenase in vitro by some of the more therapeutically effective antimetabolic drugs has been investigated. 2. Antipurine and antifolic acid drugs inhibit this system, as does folic acid. 3. Combinations of antifolic acid drugs and folic acid itself produce an additive but not synergic inhibition. 4. Antimetabolic drugs give inhibitions that are additive to those produced by antagonistic steroid hormones.

Topics: Aminopterin; Antimetabolites; Diethylstilbestrol; Enzyme Inhibitors; Estradiol; Folic Acid; Hydrogen-Ion Concentration; Hydroxysteroid Dehydrogenases; Mercaptopurine; Methotrexate; NAD; Oxidoreductases; Research; Steroids; Testosterone; Uracil

Topics: Adolescent; Antineoplastic Agents; Child; Leukemia; Mercaptopurine; Nucleosides; Prednisone; Uracil

Topics: Animals; Antimetabolites; Ascorbic Acid; Barbital; Body Fluids; Enzyme Induction; Fluids and Secretions; Hexobarbital; Mercaptopurine; Mice; Nucleosides; Pharmacology; Rats; Research; Sleep; Uracil; Urine