the effects of allopurinol, acyclovir and theophylline on the activity of adenosine deaminase (ada) were studied in 50 mm sodium phosphate buffer ph 7.5 at 27°c, using a uv– vis spectrophotometer. adenosine deaminase is inhibited by these ligands, via different types of inhibition. allopurinol, as a transition state analog of xanthine oxidase, and acyclovir competitively inhibit the catalytic a...

The aim of our study was to examine the effects of different purine nucleotides [GTP, ITP, and xanthosine 5'-triphosphate (XTP)] on receptor/G protein coupling. As a model system, we used a fusion protein of the beta(2)-adrenergic receptor and the alpha subunit of the G protein G(s). GTP was more potent and efficient than ITP and XTP at inhibiting ternary complex formation and supporting adenyl...

The changes in cellular nucleotides accompanying the phosphorylation of 2-deoxyglucose by respiring Krebs ascites tumor cells have been studied. The degradation of ATP by dephosphorylation and deamination to form ADP, AMP, IMP, and inosine in 2-deoxyglucose-treated cells was followed chromatographically and electrophoretically. A rise in cellular AMP concentration, a rise and subsequent fall in...

Liver ischemia represents a common clinical problem. In the present study, using an in vitro model of hepatic ischemia-reperfusion injury, we evaluated the potential cytoprotective effect of the purine metabolites, such as adenosine and inosine, and studied the mode of their pharmacological actions. The human hepatocellular carcinoma-derived cell line HepG2 was subjected to combined oxygen-gluc...

In a multicentre, prospective, randomised, placebo controlled study of 55 patients with histories of genital warts for at least one year, a four week course of inosine pranobex 3 g a day improved the clinical response to conventional treatment (primarily podophyllin or trichloroacetic (now called trichlorethanoic) acid). Although more patients given inosine pranobex improved than those given pl...

Purine nucleosides have been reported to extend the preservation of red cells stored in acid citrate dextrose (ACD) (1-6). This effect was originally attributed to the production of phosphorylated ribose as an energy substrate within the erythrocyte (7-9) through the action of nucleoside phosphorylase (10). This enzyme was shown to act on inosine, guanosine (11, 12), and on adenosine after its ...

Mammals can barely survive total-body ionizing irradiation greater than 10 Gy. To date, there are few drugs available for radioprotective therapy under such circumstances. Inosine, a natural derivative of adenosine, has been known to provide powerful protection for many kinds of cells and tissues against various insults both in vitro and in vivo. In the present study, we examined whether inosin...

Nucleoside triphosphate pyrophosphohydrolase has been isolated from rabbit reticulocytes. The enzyme has been pursed over 2000-fold from the cell lysate. Isolation and analysis procedures are described. The enzyme has been shown to catalyze the hydrolysis of ITP to yield IMP and PPi. Other substrates are dITP, XTP, and, to a lesser extent GTP, dGTP, UTP, and dTJTP. ATP, dATP, CTP, and dCTP are ...

Deamination of DNA bases can create missense mutations predisposing humans to cancer and also interfere with other basic molecular genetic processes; this deamination generates deoxyinosine from deoxyadenosine. In Escherichia coli, the highly conserved endonuclease V is involved in alternative excision repair that removes deoxyinosine from DNA. However, its exact activities and roles in humans ...

Adenosine and inosine are both key intracellular energy substrates for nucleotide synthesis by salvage pathways, especially during ischemic stress conditions. Additionally they both possess cell protective and cell repair properties. The objective of this study is to detect potential advantages of the combination of adenosine and inosine versus each drug alone, in terms of ventricular function,...