Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.4.17 (adenosine deaminase)
5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenosine deaminase exists in multiple molecular forms in human tissue. One form of the enzyme appears to be "particulate". Three forms of the enzyme are soluble and interconvertible with apparent molecular weights of approximately 36,000, 114,000, and 298,000 (designated small, intermediate, and large, respectively). The small form of adenosine deaminase is convertible to the large form only in the presence of a protein, which has an apparent molecular weight of 200,000 and has no adenosine deaminase activity. This conversion of the small form of the enzyme to the large form occurs at 4 degrees, exhibits a pH optimum of 5.0 to 8.0, and is associated with a loss of conversion activity. The small form of the enzyme predominates in tissue preparations exhibiting the higher enzyme-specific activities and no detectable conversion activity. The large form of adenosine deaminase predominates in tissue extracts exhibiting the lower enzyme specific activities and abundant conversion activity. The small form of adenosine deaminase shows several electrophoretic variants by isoelectric focusing. The electrophoretic heterogeneity observed with the large form of the enzyme is similar to that observed with the small form, with the exception that several additional electrophoretic variants are uniformly identified. No organ specificity is demonstrable for the different electrophoretic forms. The kinetic characteristics of the three soluble molecular species of adenosine deaminase are identical except for pH optimum, which is 5.5 for the intermediate species and 7.0 to 7.4 for the large and small forms.
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PMID:Human adenosine deaminase. Distribution and properties. 0 88

The activation of purified adenylate deaminase from the duck myocardium by K+ is accompanied by modification of the substrate specificity and by the appearance of the capacity to deaminate adenosine and adenine. Adenosine deaminase activity originates at the concentration of K+ of 0.15 M that possesses the most stimulating effect on adenylate deaminase activity; with the increase of potassium ions concentration adenosine deaminating activity is enhanced as well, with a parallel reduction of Hill's constant. The PH-dependence, mode of inhibition by phosphate ions and the effect of alkaline metals suggests that adenosine deamination is carried out by natural adenylate deaminase active centres when their conformation is changed under the activator action.
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PMID:[Allosteric modification of adenylate deaminase activity: appearance of adenosine deaminase activity as an effect of potassium ions]. 3 Dec 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

In fat cells isolated from the parametrial adipose tissue of rats, the addition of purified adenosine deaminase increased lipolysis and cyclic adenosine 3':5'-monophosphate (cyclic AMP) accumulation. Adenosine deaminase markedly potentiated cyclic AMP accumulation due to norepinephrine. The increase in cyclic AMP due to adenosine deaminase was as rapid as that of theophylline with near maximal effects seen after only a 20-sec incubation. The increases in cyclic AMP due to crystalline adenosine deaminase from intestinal mucosa were seen at concentrations as low as 0.05 mug per ml. Further purification of the crystalline enzyme preparation by Sephadex G-100 chromatography increased both adenosine deaminase activity and cyclic AMP accumulation by fat cells. The effects of adenosine deaminase on fat cell metabolism were reversed by the addition of low concentrations of N6-(phenylisopropyl)adenosine, an analog of adenosine which is not deaminated. The effects of adenosine deaminase on cyclic AMP accumulation were blocked by coformycin which is a potent inhibitor of the enzyme. These findings suggest that deamination of adenosine is responsible for the observed effects of adenosine deaminase preparations. Protein kinase activity of fat cell homogenates was unaffected by adenosine or N6-(phenylisopropyl)adenosine. Norepinephrine-activated adenylate cyclase activity of fat cell ghosts was not inhibited by N6-(phenylisopropyl)adenosine. Adenosine deaminase did not alter basal or norepinephrine-activated adenylate cyclase activity. Cyclic AMP phosphodiesterase activity of fat cell ghosts was also unaffected by adenosine deaminase. Basal and insulin-stimulated glucose oxidation were little affected by adenosine deaminase. However, the addition of adenosine deaminase to fat cells incubated with 1.5 muM norepinephrine abolished the antilipolytic action of insulin and markedly reduced the increase in glucose oxidation due to insulin. These effects were reversed by N6-(phenylisopropyl)adenosine. Phenylisopropyl adenosine did not affect insulin action during a 1-hour incubation. If fat cells were incubated for 2 hours with phenylisopropyl adenosine prior to the addition of insulin for 1 hour there was a marked potentiation of insulin action. The potentiation of insulin action by prior incubation with phenylisopropyl adenosine was not unique as prostaglandin E1, and nicotinic acid had similar effects.
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PMID:Effects of adenosine deaminase on cyclic adenosine monophosphate accumulation, lipolysis, and glucose metabolism of fat cells. 16 37

Minimum inhibitory concentrations of 9-beta-D-arabinofuranosyladenine (ara-A, adenine arabinoside, vidarabine) and a purified preparation of 9-beta-D-arabinofuranosylhypoxanthine (arabinoslhypoxanthine, ara-Hx) at end points of 50% MIC50) and 100% (MIC100) reduction to challenges of approximately 50 p.f.u. of herpes simplex virus, type 1 (HSV-1) were determined in vero renal tissue cultures. Adenosine deaminase is universally present in tissue cultures and serum. These same tests were repeated in the presence of a potent inhibitor of adenosine deaminase, R-3-(2-deoxy-beta-D-erythro-pentofuranosyl)-3,6,7,8-tetrahydroimidazo-4,5-d)-(1,3)-diazepin-8-ol (co-vidarabine, co-ara-A). Addition of co-ara-A to assays of MIC50 or MIC100 for ara-A ensures standard reproducible results which can be compared in different laboratories. After incubations of HSV-1 in infected cultures for 96 hours, 35 degrees C., with concentrations of ara-A or ara-Hx at the MIC100 and over, cells were scraped and sonicated. Supernates were then reinoculated into vero flasks free of antiviral agents to determine minimum lethal concentrations (MLC's). Standard values (microng/ml.) for ara-A with co-ara-A are 11.3 (MIC50), 17.0 (MIC100), and 34.0 (MLC) but are 68.1 (MIC50), 170.4 (MIC100) and 375 (MLC) for ara-Hx. These data confirm that as a virustatic agent (MIC100) ara-A is 10 times more active than ara-Hx. Ara-A and ara-Hx have virucidal potentials which require approximately two times the respective MIC100.
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PMID:Inhibitory and lethal concentrations of 9-beta-D-arabinofuranosyladenine and its hypoxanthine-derivative versus herpes simplex virus, type 1. 19 46

Inherited deficiencies of the enzymes adenosine deaminase (adenosine aminohydrolase; EC 3.5.4.4) and purine nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyltransferase; EC 2.4.2.1) preferentially interfere with lymphocyte development while sparing most other organ systems. Previous experiments have shown that through the action of specific kinases, nucleosides can be "trapped" intracellularly in the form of 5'-phosphates. We therefore measured the ability of newborn human tissues to phosphorylate adenosine and deoxyadenosine, the substrate of adenosine deaminase, and also inosine, deoxyinosine, guanosine, and deoxyguanosine, the substrates of purine nucleoside phosphorylase. Substantial activities of adenosine kinase were found in all tissues studied, while guanosine and inosine kinases were detected in none. However, the ability to phosphorylate deoxyadenosine, deoxyinosine, and deoxyguanosine was largely confined to lymphocytes. Adenosine deaminase, but not purine nucleoside phosphorylase, showed a similar lymphoid predominance. Other experiments showed that deoxyadenosine, deoxyinosine, and deoxyguanosine were toxic to human lymphoid cells. The toxicity of deoxyadenosine was reversed by the addition of deoxycytidine, but not uridine, to the culture medium. Based upon these and other experiments, we propose that in adenosine deaminase and purine nucleoside phosphorylase deficiency, toxic deoxyribonucleosides produced by many tissues are selectively trapped in lymphocytes by phosphorylating enzyme(s).
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PMID:Lymphospecific toxicity in adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency: possible role of nucleoside kinase(s). 20 60

Adenosine deaminase and adenosine kinase have been measured in rat liver, 12 transplantable hepatomas, regenerating, foetal and neonatal liver, adult and neonatal rat kidney and 2 transplantable kidney tumours. Adenosine, deaminase activity, relative to the normal liver value, was elevated 2-4 fold in hepatomas of rapid growth rate, was in the normal range in more slowly growing hepatomas and in regernerating liver, and was low in foetal and neonatal liver. Adenosine kinase activity was decreased, relative to rat liver values, in all the hepatomas; activity of this enzyme gave a negative correlation with tumour growth rate. Kinetic properties of the two enzymes were examined in partially purified preparations. Adenosine deaminases from both liver and rapidly growing hepatoma 3924A were subject to weak product inhibition by inosine. Adenosine kinase from liver and hepatoma 3924A was inhibited by the reaction products ADP and AMP, and the enzyme was also subject to excess substrate inhibition by concentrations of ATP in excess of 1 mM. In rat hepatoma cell lines growing in culture, the toxicity of adenosine correlated inversely with the ratio of adenosine deaminase activity to adenosine kinase activity. Chromatographic measurements showed that hepatoma cells incorporated less extracellular adenosine into their adenine nucleotide pools than did isolated liver cells. These results indicate that increased adenosine deaminase activity and decreased adenosine kinase activity may confer a selective advantage upon the cancer cell.
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PMID:Adenosine deaminase and adenosine kinase in rat hepatomas and kidney tumours. 20 96

1. Adipocytes isolated from rats 6--9 days after adrenalectomy had significantly increased sensitivity to insulin action against noradrenaline-stimulated lipolysis. In the presence of adenosine deaminase there was no significant difference in insulin sensitivity between cells from adrenalectomized and sham-operated rats. 2. Adipocytes from adrenalectomized rats had decreased lipolytic responses to all concentrations of noradrenaline and glucagon tested and a decreased lipolytic response to low but not high concentrations of corticotropin. There was no difference in lipolytic response to theophylline after adrenalectomy. Adenosine deaminase corrected the differences in response to noradrenaline and glucagon resulting from adrenalectomy. 3. In the presence of adenosine deaminase rates of lipolysis, after stimulation by high concentrations of noradrenaline, glucagon, corticotropin or theophylline, were the same in cells from adrenalectomized or sham-operated rats. 4. These findings and previously reported effects of adenosine and adrenalectomy on adipocyte function are discussed. It is proposed that changes in adipocyte hormone responsiveness after adrenalectomy may result from changes in adenosine metabolism or release.
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PMID:Alterations in response of rat white adipocytes to insulin, noradrenaline, corticotropin and glucagon after adrenalectomy. Correction of these changes by adenosine deaminase. 21 18

The analysis of progress curves using the integrated rate equation was applied to the adenosine deaminase-catalyzed conversion of adenosine to inosine. Adenosine deaminase was purified from human red blood cells of phenotypes ADA 1, ADA 2, and ADA 2-1. For all three types, no measurable product inhibition by inosine was observed. These results do not confirm the hypothesis that inosine accumulation in purine nucleoside phosphorylase deficiency causes adenosine deaminase inhibition, resulting in a common mechanism for the immune defects related to these two enzyme deficiencies.
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PMID:Use of the integrated steady state rate equation to investigate product inhibition of human red cell adenosine deaminase and its relevance to immune dysfunction. 61 71

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


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