Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a patient with paroxysmal nocturnal haemoglobinuria (PNH) enzymatic activities of erythrocytes and leucocytes were studied. Studies of autohaemolysis were also performed. The following erythrocytary enzymes were measured: Glucose-6-phosphate dehydrogenase (G-6-PD), pyruvate kinase (PK), glutathione reductase (GR), and acetylcholinesterase (AcChE). The following enzymes were measured in leucocytes: Adenosine deaminase, purine nucleoside phosphorylase, adenine phosphoribosyltransferase, hypoxanthine phosphoribosyltransferase and adenosine kinase. Normal activity of G-6-PD, GR and PK in erythrocytes was found. In leucocytes and lymphocytes activity of purine nucleoside phosphorylase was reduced. Auto-haemolysis in vitro was increased, which could not be compensated by addition of glucose or ATP.
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PMID:Erythrocyte and leucocyte enzymes in a case of paroxysmal nocturnal haemoglobinuria. 10 10

Changes in hepatic purine enzyme activities of chicks fed diets containing 11%, 20%, 43% and 80% protein were correlated with protein intake and uric acid production in order to identify those enzymes with activities that parallel closely and may regulate uric acid production. Nucleoside phosphorylase, xanthine dehydrogenase, adenylosuccinate synthetase and adenosine kinase correlated positively with protein intake and uric acid production. Adenosine deaminase, 5'-nucleotidase (AMP), adenylate deaminase and adenine phosphoribosyltransferase correlated negatively with protein intake and uric acid production. Hypoxanthine phosphoribosyltransferase and 5'-nucleotidase (IMP) were unaffected by protein intake and did not correlate with uric acid production. The ratio of adenosine kinase to adenosine deaminase correlated positively with protein intake and uric acid production. The increased activities of adenylosuccinate synthetase and adenosine kinase, along with the reduced activities of 5'-nucleotidase and adenylate deaminase, in liver from chickens fed the 80% compared with the 11% protein diet demonstrate enhanced synthesis of adenine nucleotides. Since adenine nucleotides are essential cofactors for de novo purine synthesis, it is proposed that adenylosuccinate synthetase, adenosine kinase, 5'-nucleotidase and adenylate deaminase are key enzymes involved in the regulation of purine biosynthesis.
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PMID:Protein intake, hepatic purine enzyme levels and uric acid production in growing chicks. 61 42

To evaluate the regulation of adenine nucleotide metabolism in relation to purine enzyme activities in rat liver, human erythrocytes and cultured human skin fibroblasts, rapid and sensitive assays for the purine enzymes, adenosine deaminase (EC 2.5.4.4), adenosine kinase (EC 2.7.1.20), hyposanthine phosphoribosyltransferase (EC 2.4.28), adenine phosphoribosyltransferase (EC 2.4.2.7) and 5'-nucleotidase (EC 3.1.3.5) were standardized for these tissues. Adenosine deaminase was assayed by measuring the formation of product, inosine (plus traces of hypoxanthine), isolated chromatographically with 95% recovery of inosine. The other enzymes were assayed by isolating the labelled product or substrate nucleotides as lanthanum salts. Fibroblast enzymes were assayed using thin-layer chromatographic procedures because the high levels of 5'-nucleotidase present in this tissue interferred with the formation of LaCl3 salts. The lanthanum and the thin-layer chromatographic methods agreed within 10%. Liver cell sap had the highest activities of all purine enzymes except for 5'-nucleotidase and adenosine deaminase which were highest in fibroblasts. Erythrocytes had lowest activities of all except for hypoxanthine phosphoribosyltransferase which was intermediate between the liver and fibroblasts. Erhthrocytes were devoid of 5'-nucleotidase activity. Hepatic adenosine kinase activity was thought to control the rate of loss of adenine nucleotides in the tissue. Erythrocytes had excellent purine salvage capacity, but due to the relatively low activity of adenosine deaminase, deamination might be rate limiting in the formation of guanine nucleotides. Fibroblasts, with high levels of 5'-nucleotidase, have the potential to catabolize adenine nucleotides beyond the control od adenosine kinase. The purine salvage capacity in the three tissues was erythrocyte greater than liver greater than fibroblasts. Based on purine enzyme activities, erythrocytes offer a unique system to study adenine salvage; fibroblasts to study adenine degradation; and liver to study both salvage and degradation.
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PMID:Adenine nucleotide metabolism in relation to purine enzymes in liver, erythrocytes and cultured fibroblasts. 118 98

Enzyme activities were studied in peripheral blood lymphocytes from patients infected with, or at risk for, infection with human immunodeficiency virus (HIV). No significant differences were observed in the HIV-infected and HIV-seronegative high-risk patients with regard to enzyme activities of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) and purine nucleoside phosphorylase (EC 2.4.2.1) in peripheral blood. Adenosine deaminase (EC 3.5.4.4) was significantly (P less than 0.02) depressed in asymptomatic HIV-seropositive patients and HIV-seronegative patients at high risk of HIV infection as compared with a healthy HIV-seronegative population. Adenosine kinase (AK, EC 2.7.1.20) was significantly increased in the asymptomatic seropositive (P less than 0.02) and also in the HIV-seronegative high-risk groups (P = 0.01) compared with the normal controls. AK activity was significantly lower in subjects with AIDS than in the asymptomatic (P less than 0.002) and high-risk groups (P less than 0.01). Taken together, these results indicate that adenosine deaminase and AK activities are influenced by the health of the patient, and that measurement of AK activity may prove useful in monitoring the clinical progress of patients with HIV infection.
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PMID:Depressed activities of purine enzymes in lymphocytes of patients infected with human immunodeficiency virus. 254 31

In this study enzyme activities involved in purine metabolism were measured in T and B lymphocytes separated by E and EAC rosetting methods. Adenosine deaminase, purine nucleoside phosphorylase and HGPRTase activities were significantly elevated in T cells, compared to the activities in B cells. There were no significant differences in adenosine kinase and APRTase activities between T and B lymphocytes. In contrast, PRPPsynthetase activities were higher in B cells than in T cells. The uptake of various radiolabeled precursors by mitogen stimulated lymphocytes was studied. The uptake of 14C-formate by the mitogen stimulated lymphocytes was markedly lower, compared to that of 14C-adenosine and or 14C-purine bases. The uptake of 14C-adenosine by PHA stimulated lymphocytes was considerably higher than that of Con A or PWM stimulated lymphocytes. However, the uptake of 14C-hypoxanthine into lymphocytes stimulated with PWM was increased by comparison with unstimulated lymphocytes. From these results it seems that adenosine plays a central role in the metabolism of T cells, and that purine bases are preferentially utilized in B cells.
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PMID:The differences in purine metabolism between T and B lymphocytes. 625 35

Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), 5'nucleotidase (5'NT), ecto-5'NT, hypoxanthine-guanine phosphoribosyltransferase(HGPRT), adenine phosphoribosyltransferase(APRT), adenosine kinase(AK), AMP deaminase (AMPD) and adenylate kinase(AdKin) activities were assayed in leukemic cells from bone marrow and/or peripheral blood of 43 newly diagnosed children with acute lymphoblastic leukemia(ALL). These enzyme activities have been investigated in relation to some immunological markers. ADA activity was higher in E-rosette positive leukemia(E+ ALL), while HGPRT, APRT, PNP, 5'NT, ecto-5'NT and AdKin activities were found to be lower in E+ ALL as compared to E- ALL. In common ALL (cALL) antigen positive leukemia, mean ADA activity was significantly lower as compared to cALL- leukemia, whereas PNP, 5'NT, ecto-5'NT and AdKin activities were significantly higher. cALL cells with cytoplasmic immunoglobulin M(IgM) heavy chains were found to have mean 5'NT activities twice as high as cALL cells lacking cytoplasmic IgM heavy chains. In two patients who had surface immunoglobulins on their cell membranes, low 5'NT activities were found. When measuring enzyme activities after 2-4 days of prednisone monotherapy, only mean ADA and HGPRT activities decreased in non-B, non-T ALL. These decreases were not significant in T-ALL patients. Mean enzyme activities in the leukemic cells of five patients with relapse were comparable to those in newly diagnosed patients, except for 5'NT, which was found to be within the activity range of control peripheral blood lymphocytes. It is concluded that ADA and AdKin activities are suitable as markers for E+ ALL and cALL+ leukemias respectively. 5'NT might help to distinguish between cALL cells having and lacking pre-B characteristics. Since 5'NT activity may also be decreased in B-ALL, it is not suitable as a T-ALL marker. Enzymes of purine metabolism in leukemic relapse need further investigation.
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PMID:Purine metabolism in childhood acute lymphoblastic leukemia: biochemical markers for diagnosis and chemotherapy. 631 Feb 74

Adenosine deaminase (ADA), 5'nucleotidase (5'NT), ecto-5'NT, purine nucleoside phosphorylase (PNP), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), adenine phosphoribosyltransferase (APRT), adenosine kinase (AK), AMP-deaminase (AMPD) and adenylate kinase (AdKin) activities were assayed in peripheral blood lymphoid cells from 20 patients with B-cell type chronic lymphocytic leukemia (CLL). Significantly decreased mean activities of ADA, 5'NT, ecto-5'NT, PNP and AMPD were observed when comparing B-CLL lymphoid cells with control peripheral blood lymphocytes (PBL). AK and AdKin activities however, were found to be higher in B-CLL. Relatively wide ranges of ADA and 5'NT activity were observed. In patients with paraproteinaemia, 5'NT activity was found to be relatively high and in the range of the activities in normal PBL. ADA activity seemed to be slightly higher in patients without paraproteinaemia. No correlation could be found between the enzyme activities and the number of cells rosetting with sheep erythrocytes or bearing surface immunoglobulin (sIg). A relationship was suggested between 5'NT activity and Ig production.
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PMID:Enzymological studies in chronic lymphocytic leukemia. 640 72

Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activities were measured in normal human B lymphocytes, T lymphocytes, and T gamma and T mu lymphocyte subsets. Total ADA activity in T cells was 5.5U, activity in T gamma and T mu cells was 3.7U and 5.3U, respectively; B cell ADA levels were 3.3U. PNP activity in T cells was 119U, activity in T gamma and T mu cells was 75U and 155U, respectively. B cell PNP activity was 88U. HGPRT activity in T cells was 20.9U; T gamma and T mu HGPRT levels were 13.0U and 52U respectively. B cell HGPRT levels were 46.8U. These data provides further evidence for the biochemical heterogeneity of normal human lymphocytes.
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PMID:Adenosine deaminase, nucleoside phosphorylase and hypoxanthine-guanine phosphoribosyltransferase activity in normal lymphocyte subpopulations. 681 86

Many enzymes are involved in the biosynthesis, interconversion, and degradation of purine compounds. The exact function of these enzymes is still unknown, but they seem to play important roles other than in purine metabolism. To elucidate their functional roles, it is imperative to clarify their tissue distribution at the cellular or subcellular level. The present review summarizes the currently available information about their histochemical localization and proposed functions. In general, 5'-nucleotidase has been considered as a marker enzyme for the plasma membrane, and is considered to be a key enzyme in the generation of adenosine, a potential vasodilator. However, from its wide range of localization in tissues it is also considered to be related to the membrane movement of cells in the transitional epithelium, cellular motile response, transport process, cellular growth, synthesis of fibrous protein and calcification, lymphocyte activation, neurotransmission, and oxygen sensing mechanism. Adenosine deaminase (ADA) is present in all tissues in mammals. Although the main function of ADA is the development of the immune system in humans, it seems to be associated with the differentiation of epithelial cells and monocytes, neurotransmission, and maintenance of gestation. Purine nucleoside phosphorylase (PNP) is generally considered as a cytosolic enzyme, but recently, mitochondrial PNP, a different protein from cytosolic PNP, was reported. PNP is also widely expressed in human tissues. It is found in most tissues of the body, but the highest activity is in peripheral blood granulocyte and lymphoid tissues. It is also related to the development of T-cell immunity in humans as is ADA. Moreover, its contribution to centriole replication and/or regulation of microtubule assembly has been suggested. Immunohistochemical localization of xanthine oxidase has been reported in various tissues from various animal species. Xanthine oxidase has been suggested to be involved in the pathogenesis of post-ischemic reperfusion tissue injury through the generation of reactive oxygen species, while the extensive tissue localization of xanthine dehydrogenase/oxidase suggests several other roles for this enzyme, including a protective barrier against bacterial infection by producing either superoxide radicals or uric acid. Furthermore, an involvement in cellular proliferation and differentiation has been suggested. Urate oxidase is generally considered a liver-specific enzyme, except for bovines which possess this enzyme in the kidney. Urate oxidase is exclusively located in the peroxisomes of fish, frogs, and rats, but was lost in birds, some reptiles, and primates during evolution. A histochemical demonstration of allantoin-degrading enzymes has not been performed, but these enzymes have been located in peroxisomes by sucrose density gradient centrifugation. AMP deaminase activity is higher in skeletal muscle than in any other tissues. AMP deaminase may be involved in a number of physiological processes, such as the conversion of adenine nucleotide to inosine or guanine nucleotide, stabilizing the adenylate energy charge, and the reaction of the purine nucleotide cycle. There are three distinct isozymes (A, B, C) with different kinetic, physical, and immunological properties. Isozymes A, B, C have been isolated from muscle, liver (kidney), and heart tissue, respectively. In the muscle, AMP deaminase isozymes exist in a different part, suggesting a multiple functional role of this enzyme. High hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity is found in some regions of a normal adult human brain. However, very little is known regarding the histochemical tissue localization of HGPRT. Immunohistochemical localization of its developmental expression suggests that HGPRT may not be essential for purine nucleotide supplement in the segmentation of brain cells, but may play a significant role in the developing hippocampus.
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PMID:Enzymes involved in purine metabolism--a review of histochemical localization and functional implications. 1050 47