Xanthine phosphoribosyltransferase (XPRT) and hypoxanthine-guanine (HGPRT) are purine salvaging enzymes of Leishmania donovani with distinct 6-oxopurine specificities. LdXPRT phosphoribosylates xanthine, hypoxanthine, guanine, preference toward whereas LdHGPRT only hypoxanthine guanine. In our study, was used as a model to understand these base Mutating I209 V, the conserved residue found in HG...

In vitro kinetic studies revealed that Taenia crassiceps larvae absorb purine bases (adenine and hypoxanthine) and nucleosides (adenosine and uridine) by mediated transport. Pyrimidines (thymine, uracil, and cytosine) are absorbed primarily by diffusion. The presence of hypoxanthine stimulated adenosine uptake, an effect which was enhanced by preloading the worms with hypoxanthine. Furthermore,...

Hypoxanthine is a mutagenic purine base that most commonly arises from the oxidative deamination of adenine. Damaged bases such as hypoxanthine are associated with carcinogenesis and cell death. This inevitable damage is counteracted by glycosylase enzymes, which cleave damaged bases from DNA. Alkyladenine DNA glycosylase (AAG) is the enzyme responsible for excising hypoxanthine from DNA in hum...

Reactive oxygen species (ROS) generation during purine metabolism is associated with xanthine oxidase and uric acid. However, the direct effect of hypoxanthine on ROS generation and atherosclerosis has not been evaluated. Smoking and heavy drinking are associated with elevated levels of hypoxanthine. In this study, we investigated the role of hypoxanthine on cholesterol synthesis and atheroscle...

The course of the reaction sequence hypoxanthine----xanthine----uric acid catalysed by xanthine:oxygen oxidoreductase from milk was investigated on the basis of u.v. spectra taken during the course of hypoxanthine and xanthine oxidations. It was found that xanthine accumulated in the reaction mixture when hypoxanthine was used as a substrate. The time course of the concentrations of hypoxanthin...

1. The hepatic metabolism of hypoxanthine was investigated by studying both the fate of labelled hypoxanthine, added at micromolar concentrations to isolated rat hepatocyte suspensions, and the kinetic properties of purified hypoxanthine/guanine phosphoribosyltransferase from rat liver. 2. More than 80% of hypoxanthine was oxidized towards allantoin; less than 5% of the label was incorporated i...

Two distinct transporters for nucleobases have been characterized in LLC-PK1 cells. The first system accumulates hypoxanthine against a concentration gradient in the presence of sodium. The sodium-dependent uptake of hypoxanthine was saturable at 22 degrees C with a Km value of 0.79 +/- 0.43 microM, a Vmax of 15 +/- 4 pmol/mg protein/60 s, and a Na+:hypoxanthine coupling stoichiometry of 1.27 +...

The antitumor effect of oxygen radicals produced by hypoxanthine and xanthine oxidase reaction was studied in an experimental rabbit model. VX2 carcinomas were transplanted into rabbit hind legs. Hypoxanthine was administered continuously through the ear vein, while xanthine oxidase was administered simultaneously through the femoral artery. As a result, hypoxanthine and xanthine oxidase reacte...

In previous studies from this laboratory, human bone marrow hypoxanthine concentrations were found to average 7.1 microM, three times higher than plasma hypoxanthine concentrations measured simultaneously. To assess the significance of this finding, the relationship between hypoxanthine concentration and the rate of purine nucleotide synthesis by the de novo pathway was studied in normal human ...