Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has recently been reported that human osteosarcomas may lack the purine salvage pathway enzyme, hypoxanthine:guanine phosphoribosyltransferase (EC 2.4.2.8). We have established a quantitative assay for measurement of this enzyme in human osteosarcoma xenografts with analysis of products by thin-layer chromatography. Nucleotidase or phosphatase activity was readily detected and could be abolished by preheating cytosol at 60 degrees C for 10 min and performing the assay at pH 10. Alternatively, the use of 25 mM NaF at pH 7.4 also inhibited this activity. The pH optimum for this enzyme in red blood cell sonicates and tumor cytosols was pH 10. All six human osteosarcoma xenografts contained hypoxanthine:guanine phosphoribosyltransferase activity ranging from 0.97 to 4.06 nmol/min/mg of protein at pH 7.4. Control human red blood cell sonicates demonstrated activity of 0.83 nmol/min/mg of protein. These data demonstrate that human osteosarcoma xenografts contain substantial activities of this purine salvage pathway enzyme.
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PMID:Hypoxanthine:guanine phosphoribosyltransferase activity in xenografts of human osteosarcoma. 346 7

Several aspects of purine metabolism were studied in peripheral blood mononuclear cells and fibroblasts from a patient with purine nucleoside phosphorylase deficiency and compared to cells from normal controls. Intact cells were incubated with radioactive purine bases and all purine metabolites were extracted and analyzed. Incubation of purine nucleoside phosphorylase-deficient cells with [3H]hypoxanthine and [3H]guanine resulted in the accumulation of large proportions of the incorporated radioactivity into inosine (60-80%) and to lesser extent into guanosine (15-30%), respectively, whereas normal cells accumulated only minor amounts of inosine and guanosine. This observation indicates that purine nucleoside phosphorylase, together with hypoxanthine-guanine phosphoribosyltransferase and nucleoside monophosphate phosphatase, participate in remarkably active inosine and guanosine cycles. These purine nucleoside cycles may play a role in the regulation of intracellular purine nucleotide levels. The absence of these cycles in purine nucleoside phosphorylase-deficient patients may be detrimental to the differentiation of lymphocytes.
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PMID:Evidence for active purine nucleoside cycles in human mononuclear cells and cultured fibroblasts. 681 84

Hyperuricemia (serum urate level >7 mg/dL) is caused by accelerated generation of uric acid and/or impaired excretion in the kidney. It is classified into three types (overproduction, underexcretion and mixed types). The typical cases with the type of uric acid overproduction are hypoxanthine guanine phosphoribosyl transferase deficiency due to HPRT gene abnormality, excessive consumption of purine-rich diet, and cytolysis induced by chemotherapy for blood neoplasm, those with the type of underexcretion are familial juvenile hyperuricemic nephropathy due to uromodulin gene abnormality and abrupt body weight loss due to low calorie diet, and those with the mixed type are glucose 6-phosphatase deficiency due to glucose 6-phosphatase gene abnormality and excessive consumption of alcohol beverages.
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PMID:[Definition and classification of hyperuricemia]. 1840 7