Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Purine nucleoside phosphorylase and adenosine deaminase (ADA) were studied in normal red blood cells and lymphocytes and in the cells of a family with a child with a defective T-cell-and normal B-cell immunity. 2. In the propositus no purine nucleoside phosphorylase (NP) activity could be detected in her red cells and lymphocytes, while the ADA activity was somewhat increased. The NP activities of the father, mother and brother of the propositus are in the heterozygote range. The decreased activity of NP was not only found for the substrate inosine but also when guanosine or xanthosine were used as substrate. The mode of inheritance is autosomal recessive. 3. With starch gel electrophoresis no NP activity could be detected in the patient's haemolysate. The electrophoretic patterns of NP from the father, mother and brother of the patient seem to be the same as for normal NP with six bands of NP activity. 4. The nucleoside phosphorylases of the father, mother and brother of the patient were characterized by an increased KM for the substrate inosine, normal pH optimum and a decreased heat stability.
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PMID:An abnormal form of purine nucleoside phosphorylase in a family with a child with severe defective T-cell-and normal B-cell immunity. 1 Jan 3

A 5-year-old girl with a history of recurrent infection and anaemia has no measurable purine nucleoside phosphorylase (N.P.) activity in her red blood-cells. Her serum-immunoglobulin levels are normal, as are her antibody responses to thymus dependent and independent antigens. However, she has severe lymphopenia, pronounced depression of lymphocyte response to mitogenic and allogeneic cell stimuli, and greatly decreased T-cell rosette formation. Her parents are second cousins; their red cells contain less than half the normal level of N.P. activity. They also share an unusual N.P. isozyme pattern indicative of molecular hybridisation between catalytically active and inactive subunits, which strongly supports the assumption that they are heterozygous and their daughter is homozygous for a "silent" allele at the N.P. gene locus. Inherited deficiency of adenosine deaminase, an enzyme catalysing a reaction only one metabolic step away from that of N.P., is known to cause immunodeficiency. It is therefore very likely that this patient's lack of demonstrable N.P. activity is responsible for her syndrome.
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PMID:Nucleoside-phosphorylase deficiency in a child with severely defective T-cell immunity and normal B-cell immunity. 4 76

Rates of purine synthesis de novo, as measured by the incorporation of [14C]formate into newly synthesized purines, have been determined in cultured human fibroblasts derived from normal individuals and from patients deficient in adenosine deaminase, purine nucleoside phosphorylase, or hypoxanthine phosphoribosyltransferase, three consecutive enzymes of the purine salvage pathway. All four types of cell lines are capable of incorporating [14C]formate into purines at approximately the same rate when the assays are conducted in purine-free medium. The purine overproduction that is characteristic of a deficiency in either the transferase or the phosphorylase and that results from a block in purine reutilization can be demonstrated by the resistance of [14C]formate incorporation into purines to inhibition by hypoxanthine in the case of hypoxanthine phosphoribosyltransferase-deficient fibroblasts and by resistance to inhibition by inosine in the case of purine nucleoside phosphorylase-deficient fibroblasts.
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PMID:Purine metabolism in cultured human fibroblasts derived from patients deficient in hypoxanthine phosphoribosyltransferase, purine nucleoside phosphorylase, or adenosine deaminase. 9 41

Intact cells of Bacillus cereus catalyze the breakdown of exogenous AMP to hypoxanthine and ribose 1-phosphate through the successive action of 5'-nucleotidase, adenosine deaminase, and inosine phosphorylase. Inosine hydrolase was not detectable, even in crude extracts. Inosine phosphorylase causes a "translocation" of the ribose moiety (as ribose 1-phosphate) inside the cell, while hypoxanthine remains external. Even though the equilibrium of the phosphorolytic reaction favors nucleoside synthesis, exogenous inosine (as well as adenosine and AMP) is almost quantitatively transformed into external hypoxanthine, since ribose 1-phosphate is readily metabolized inside the cell. Most likely, the translocated ribose 1-phosphate enters the sugar phosphate shunt, via its prior conversion into ribose 5-phosphate, thus supplying the energy required for the subsequent uptake of hypoxanthine in B. cereus.
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PMID:Utilization of exogenous purine compounds in Bacillus cereus. Translocation of the ribose moiety of inosine. 10 Apr 97

The activity of adenosine deaminase (EC 3.5.4.4.) was significantly lower in lymphocytes from patients with lung cancer than in those from healthy subjects, whereas the activity of purine nucleoside phosphorylase (EC 2.4.2.1.) was significantly higher in lymphocytes from the patients than in those from normal controls. When the one activity was plotted against the other, the plots for patients with lung cancer were all outside the frame formed by the lower and higher limits of the standard deviation of the mean of normal activities of the two enzymes. The ratio of adenosine deaminase activity to purine nucleoside phosphorylase activity was lower in patients with lung cancer than in controls. The possible effect of this ratio on the function of lymphocytes was briefly discussed. These enzyme activities were suggested to be useful measures of the immune responsiveness of patients with lung cancer.
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PMID:Adenosine deaminase and purine nucleoside phosphorylase activities in lymphocytes from patients with lung cancer. 10 12

Activities of adenosine deaminase, adenosine kinase and purine nucleoside phosphorylase were determined in extracts prepared from human skin fibroblast strains derived from 7 normal newborn males and 4 normal adult males. All strains were harvested between passages 9 and 12. Adenosine deaminase activity in adult strains, 40.80 +/- 1.76 (mean +/- S.E.) nanomoles/min per mg protein, was almost twice the activity in neonatal strains, 22.40 +/- 3.02. This difference was significant at the 99.5% confidence level. Moreover, there was no overlap between the adult and neonatal activities. In contrast, adenosine kinase and purine nucleoside phosphorylase activities did not differ with the age of the donor.
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PMID:Adenosine deaminase activity in human diploid skin fibroblasts varies with the age of the donor. 10 69

The immunodeficient state associated with adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) deficiency may result from the selective phosphorylation by thymus-derived lymphocytes of the ADA substrate deoxyadenosine and the PNP substrate deoxyguanosine, leading to the intracellular trapping of toxic deoxyribonucleoside triphosphates. Agents such as deoxycytidine might be able to favourably modify the immunodeficient state by inhibiting deoxyribonucleoside phosphorylation. Deficiencies of other nucleotide catabolic enzymes, if selectively expressed by lymphocytes, might also lead to immunodeficiency via nucleoside trapping in lymphoid tissues. Purine deoxyribonucleoside analogues, either alone or in combination with ADA inhibitors, may have value as lymphospecific antimetabolites.
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PMID:Deoxyribonucleoside toxicity in adenosine deaminase and purine nucleoside phosphorylase deficiency: implications for the development of new immunosuppressive agents. 11 60

Deoxyadenosine and deoxyguanosine are toxic to human lymphoid cells in culture and have been implicated in the pathogenesis of the immunodeficiency states associated with adenosine deaminase and purine nucleoside phosphorylase deficiency, respectively. We have studied the relative incorporation of several labeled nucleosides into DNA and into nucleotide pools to further elucidate the mechanism of deoxyribonucleoside toxicity. In the presence of an inhibitor of adenosine deaminase [erythro-9-(2-hydroxy-3-nonyl)adenine [EHNA], 5 muM], deoxyadenosine (1-50 muM) progressively decreased the incorporation of thymidine, uridine, and deoxyuridine into DNA, but did not affect uridine incorporation into RNA. This decrease in DNA synthesis was associated with increasing dATP and decreasing dCTP pools. Likewise, incubation of cells with deoxyguanosine caused an elevation of dGTP, depletion of dCTP, and inhibition of DNA synthesis. To test the hypothesis that dATP and dGTP accumulation inhibit DNA synthesis by inhibiting the enzyme ribonucleotide reductase, simultaneous rates of incorporation of [(3)H]uridine and [(14)C]thymidine into DNA were measured in the presence of deoxyadenosine plus EHNA or deoxyguanosine, and in the presence of hydroxyurea, a known inhibitor of ribonucleotide reductase. Hydroxyurea (100 muM) and deoxyguanosine (10 muM) decreased the incorporation of [(3)H]uridine but not of [(14)C]thymidine into DNA; both compounds also substantially increased [(3)H]cytidine incorporation into the ribonucleotide pool while reducing incorporation into the deoxyribonucleotide pool. In contrast, deoxyadenosine plus EHNA did not show this differential inhibition of [(3)H]uridine incorporation into DNA, and the alteration in [(3)H]cytidine incorporation into nucleotide pools was less impressive. These data show an association between accumulation of dATP or dGTP and a primary inhibition of DNA synthesis, and they provide support for ribonucleotide reductase inhibition as the mechanism responsible for deoxyguanosine toxicity. Deoxyadenosine toxicity, however, appears to result from another, or perhaps a combination of, molecular event(s).
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PMID:Purinogenic immunodeficiency diseases. Differential effects of deoxyadenosine and deoxyguanosine on DNA synthesis in human T lymphoblasts. 11 1

Activities of adenosine deaminase (ADA), adenosine kinase (AK), adenine phosphoribosyltransferase (APRT), hypoxanthine guanine phosphoribosyltransferase (HGPRT), and purine nucleoside phosphorylase (PNP), all enzymes of the purine interconversion system, were determined in lymphocytes of 25 patients with chronic lymphatic leukemia (CLL) and in 23 controls. A statistically significant decrease of PNP activities and a reduction of ADA activities at borderline levels were found in the patients, whereas for the other enzymes assayed no deviation from normal values was observed.
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PMID:Enzymes of the purine interconversion system in chronic lymphatic leukemia: decreased purine nucleoside phosphorylase and adenosine deaminase activity. 11 97

The absence of erythrocytic adenosine deaminase (ADA) or purine nucleoside phosphorylase (PNP) has been associated with severe immunodeficiency disease in children. We have developed a cell culture model to study the possible relationships between purine salvage enzymes and immunologic function using an established T cell lymphosarcoma (S49) and a potent inhibitor of ADA, erythro-9(2-hydroxy-3-nonyl) adenine (EHNA). Wild-type S49 cells are killed by dexamethasone or dbc AMP, and adenosine (5 muM) in the presence of an ADA inhibitor (6 muM EHNA) also prevents the growth of and kills these S49 cells. It has been proposed that adenosine is toxic to lymphoid cells by virtue of its ability to increase the intracellular concentrations of cyclic AMP. We examined the sensitivity of three mutants of S49 cells, with distinctive defects in some component of cyclic AMP metabolism or action, to killing by adenosine and EHNA. All three mutants are resistant to killing by isoproterenol or cholera toxin and two are resistant to dbc AMP itself, but all are sensitive to killing by adenosine and EHNA. Similarly, two dexamethasone-resistant S49 mutants are as sensitive to adenosine and EHNA as are the wildtype cells. We have also simulated the purine nucleoside phosphorylase deficiency in S49 cells by adding inosine and adenosine to the growth medium. In the presence of EHNA or inosine, the toxic effects of adenosine can be partially reversed by addition of (10-20 muM) uridine, an observation suggesting that adenosine is toxic as the result of its inducing pyrimidine starvation.
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PMID:Characterization of a cell culture model for the study of adenosine deaminase- and purine nucleoside phosphorylase-deficient immunologic disease. 18 61


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