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:3.5.4.4 (adenosine deaminase)
5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of myocardial adenosine kinase (E.N. 2.7.1.20) in a number of species was assayed. Rat heart contained the highest specific activity. From this source adenosine kinase was purified in a simple way 80-fold, until it was free of adenosine deaminase activity. A molecular weight of about 39 000 was measured. NSC 113939 (1), NSC 113940 and 8-azaadenosine inhibited myocardial adenosine kinase. Dipyridamole stimulated the enzyme at high adenosine levels, and inhibited at low substrate concentrations. A number of divalent cations could (partially) substitute for Mg2+. The optimal concentration of MgCl2 or MnCl2 was about 0.5 mM; concentrations exceeding 1 mM inhibited severely. An apparent Km for ATP of 0.1 mM was measured, whereas an apparent Km for adenosine of 0.5 muM was was found. The latter increased to 3.3 muM, when dipyridamole was added. Replacement of ATP by GTB or ITP increased the activity, and UTP and CTP were inferior as a phosphate donor.
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PMID:Partial purification and properties of rat-heart adenosine kinase. 7 32

Steroidogenesis by Y-1 adrenal tumor cells in culture is stimulated by ATP, adenyl-5'-yl imidodiphosphate (App(NH)), adenosine 5'(beta, alpha-methylene)triphosphate (App(CH2)p), ADP, AMP, NAD, FAD, and adenosine but not by adenine or other nucleoside triphosphates. ATP, App(NH)p, App(CH2)p, and adenosine are active in the micromolar range. Like adrenocorticotropic hormone (ACTH), the onset of stimulation is immediate and occurs to the same extent. Also active are 2'- and 5'-deoxyadenosine and 2-chloroadenosine whereas adenine xyloside, L-riboside, or arabinoside have very low activity. Stimulation is accompanied by rounding of the cells. Dipyridamole, an inhibitor of adenosine transport, increased the response to low concentrations of adenosine, suggesting that adenosine acts externally. Stimulation of steroidogenesis by adenosine or phosphorylated adenosine compounds fails to occur in the presence of crystalline adenosine deaminase, and the effect of the enzyme on adenosine, ATP, or NAD stimulation is reversed by the competitive inhibitor erythro-9-[3-(nonane-2-ol)]adenine. This suggests that the enzyme acts specifically on adenosine and a requirement for the conversion of the above compounds to adenosine seems probable. The inhibition of cAMP effects by adenosine deaminase suggests that some of its effects are also mediated by conversion to adenosine. Similar stimulation is seen in I-10 Leydig tumor cells, but an ACTH-resistant mutant of Y-1 cells, called OS-3, is relatively resistant to adenosine. Adenosine and 2-chloroadenosine stimulate adenylate cyclase in membranes from Y-1 and I-10 cells at concentrations slightly greater than are effective for steroidogenesis. Other nucleosides are ineffective. Like the NH2-terminal 24 residues of adrenocorticotropic hormone (1-24 ACTH), the adenosine effect in Y-1 membranes is rapid and is on the Vmax intercept (versus ATP) and not on the Km. In contrast to steroidogenesis, adenosine is only a partial agonist for adenylate cyclase. It effect occurs in the presence of ITP, GTP, or guanyl-5'-yl imidodiphosphate (Gpp(NH)p). Theophylline inhibits adenosine-stimulated steroidogenesis. Inhibition of adenylate cyclase occurs in the same concentration range but is of the mixed type.
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PMID:Activation of steroidogenesis and adenylate cyclase by adenosine in adrenal and Leydig tumor cells. 18 24

A complete deficiency of inosine triphosphate pyrophosphohydrolase (ITPase) has been identified, together with high concentrations (mean 157 mumol/l) of the unusual nucleotide ITP, in the erythrocytes of 3 members of a consanguineous United Kingdom kindred. The defect has been noted previously in North America and Sweden, but even in presumed homozygotes some residual ITPase activity was reported. Homozygosity for the defect has not been associated previously with any clinical abnormality. In this kindred it was co-existent with adenosine deaminase (ADA) deficient severe combined immunodeficiency. Since the genes for both ITPase and ADA are localised on the same chromosome, segregation analysis of ITPase and ADA activity was undertaken in available kindred members. The results confirmed an autosomal recessive mode of inheritance for ITPase deficiency, but suggested that the co-existence with ADA deficiency was coincidental.
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PMID:Inosine triphosphate pyrophosphohydrolase deficiency in a kindred with adenosine deaminase deficiency. 216 85

The enzymatic inosine 5'-monophosphate assay described by Grassl [in, Methods of Enzymatic Analysis (H. U. Bergman, ed.), pp. 2168-2171, Academic Press, New York (1974)] is highly nonspecific, as ITP, ATP, ADP, AMP, and adenosine react stoichiometrically. The reactivity with the adenine derivatives is due to the tri- and diphosphatase activity of alkaline phosphatase (AP), coupled with adenosine deaminase (and possibly AMP deaminase) contamination of commercially available preparations of AP, purine-nucleoside phosphorylase, and/or xanthine oxidase. The inclusion of coformycin (0.05 microgram/ml), a potent inhibitor of these deaminases, completely eliminated the cross-reactivity. ITP, however, still reacted stoichiometrically due to the tri- and diphosphatase activity of AP. Meyer and Terjung [Amer. J. Physiol. 237 C111-C118 (1979)] introduced a modification of Grassl's procedure, substituting 5'-nucleotidase for AP. It has been found that this disallows reactivity with ATP, ADP, and ITP but that AMP and adenosine still react completely. Coformycin prevents this cross-reactivity. It is therefore recommended that the assay be carried out with 5'-nucleotidase (instead of AP) and coformycin, in order to achieve a more specific assay, and one more suitable for use with whole tissue extracts.
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PMID:An enzymatic inosine 5'-monophosphate assay of increased specificity. 298 81

Adenine nucleotides displace the binding of the selective adenosine A-1 receptor ligand [3H]cyclopentyladenosine (CPA) to rat brain membranes in a concentration-dependent manner, with the rank order of activity being ATP greater than ADP greater than AMP. Binding was also displaced by GTP, ITP, adenylylimidodiphosphate (AppNHp), 2-methylthioATP, and the beta-gamma-methylene isostere of ATP, but was unaffected by the alpha-beta-methylene isosteres of ADP and ATP, and UTP. At ATP concentrations greater than 100 microM, the inhibitory effects on CPA binding were reversed, until at 2 mM ATP, specific binding of CPA was identical to that seen in controls. Concentrations of ATP greater than 10 mM totally inhibited specific binding. Inclusion of the catabolic enzyme adenosine deaminase in the incubation medium abolished the inhibitory effects of ATP, indicating that these were due to adenosine formation, presumably due to ectonucleotidase activity. The inhibitory effects were also attenuated by the alpha-beta-methylene isostere of ATP, an ectonucleotidase inhibitor. Adenosine deaminase, alpha-beta-methylene ATP (100 microM), and beta-gamma-methylene ATP (100 microM) had no effect on the "stimulatory" phase of binding, although GTP (100 microM) slightly attenuated it. Comparison of the binding of [3H]CPA in the absence and presence of 2 mM ATP by saturation analysis showed that the KD and apparent Bmax values were identical. Examination of the pharmacology of the control and "ATP-dependent" CPA binding sites showed slight changes in binding of adenosine agonists and antagonists. The responses observed with high concentrations of ATP were not observed with GTP, AppNHp, the chelating agents EDTA and EGTA, or inorganic phosphate. The divalent cations Mg2+ and Ca2+ at 10 mM attenuated the stimulatory actions of high (2 mM) concentrations of ATP, whereas EGTA and EDTA (10 mM) enhanced the "stimulatory" actions of ATP. EDTA (10 mM) abolished the inhibitory effects of ATP, indicating a specific dependence on Mg2+ for the inhibitory response. The effects of ATP on [3H]CPA binding were reversible for antagonists but not agonists. The mechanism by which ATP reverses its own inhibitory action on adenosine A-1 radioligand binding is unclear, and from the observed actions of the divalent cations and chelating agents probably does not involve a phosphorylation-dependent process.
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PMID:Effects of purine nucleotides on the binding of [3H]cyclopentyladenosine to adenosine A-1 receptors in rat brain membranes. 308 5

By light and electron microscopy, we observed foamy cells in the spleens from a patient with hemolytic anemia due to red cell adenosine deaminase (ADA) overproduction, a patient with rheumatoid arthritis (RA) treated with gold, and patients with idiopathic thrombocytopenic purpura (ITP). The foamy cells associated with red cell ADA overproduction were essentially similar to Gaucher-like cells described in patients with thalassemia, and it was suggested that the accelerated destruction of red cells was one of the factors responsible for the development of foamy cells. Foamy cells in ITP and RA were closely associated with an increased destruction of platelets in the spleen. Morphologic transitions between phagocytosed platelets and myelin-like materials were traced in these disorders. In RA, however, foamy cells were heterogeneous from an ultrastructural standpoint, with different cytoplasmic inclusions. In addition to myelin-like materials, dense bodies, vacuoles with flocculent materials, and gold were noted in most of foamy cells. As gold compounds are known to inhibit lysosomal enzymes, we surmise that an acquired disturbance in lysosomal digestion is partially responsible for the accumulation of intermediate metabolites. In the pathogenesis of foamy cells associated with blood cell dyscrasia, the accelerated destruction of blood cells and/or acquired disorders in catabolic pathways within the macrophages are suggested to be the underlying mechanism of an intralysosomal accumulation of incompletely degraded cellular debris.
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PMID:Three kinds of foamy cells in the spleen: comparative histochemical and ultrastructural studies. 404 43

1. Tubule fragments were isolated from renal cortex of fed rats. 2. Gluconeogenesis from lactate was significantly increased by low concentrations of exogenous ATP, ADP, AMP adenylyl (beta, gamma-methylene)diphosphonate and, to a lesser extent, by ITP and inosine. GTP was slightly inhibitory. Hypoxanthine was ineffective. Exogenous adenosine deaminase slightly decreased gluconeogenesis and was additive in effect to GTP. Adenosine deaminase did not abolish the stimulatory effects of ATP or cyclic AMP. 3. 40 microM ATP also stimulated gluconeogenesis from pyruvate, malate, succinate, 2-oxoglutarate and glutamine, but had no effect when glycerol or fructose were used as substrates. 4. With lactate as substrate the effect of 40 microM ATP was additive to the maximal stimulations of gluconeogenesis seen with 1 microM noradrenalin or 0.1 microM angiotensin II, but was not additive to the stimulatory effect of 0.1 mM cyclic AMP. 5.40 microM ATP had no effect upon either the tubule content of cyclic AMP or upon 45Ca efflux from prelabelled tubules. 6. Addition of ouabain or removal of extracellular K+ diminished the stimulatory effects of ATP and cyclic AMP. 7. Extracellular ATP was rapidly metabolized by tubule fragments, with resulting accumulation of adenosine. Further metabolism resulting in formation of inosine, hypoxanthine, xanthine and uric acid was also observed. Cyclic AMP was metabolized less rapidly, with no accumulation of adenosine. 8. The effects of purinergic agents on gluconeogenesis are discussed.
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PMID:Stimulation of renal gluconeogenesis by exogenous adenine nucleotides. 629 8

Biochemical and immunological properties of lymphocytes were measured repetitively over a period of 40 mo during enzyme replacement by transfusion in a child with adenosine deaminase (ADA) deficiency and severe combined immunodeficiency disease. Catalytically defective ADA protein is present in the child's cells. ADA activity in his lymphocytes is 7 nmol/min per 10(8) cells with 51 ng of ADA protein/10(8) cells by radioimmunoassay. ADA activities in normal cord and adult lymphocytes average 193 and 92 nmol/min per 10(8) cells, respectively, with 429 and 223 ng of ADA protein/10(8) cells. Deoxy(d)ATP accumulates in the patient's erythrocytes and lymphocytes. Transfusion of irradiated packed erythrocytes partially corrects the metabolic defects. Frank metabolic relapse occurs if transfusions are discontinued for several months. The amounts of dATP in erythrocytes and lymphocytes averaged 13 and 2 times normal, respectively, during periods when transfusions were administered every 2-4 wk. Deoxyguanosine triphosphate and deoxycytidine triphosphate in lymphocytes were normal on 11 occasions, but deoxyribosylthymine triphosphate was ninefold increased. On 11 occasions dATP was measured in lymphocytes and erythrocytes isolated simultaneously. There was a positive, but statistically insignificant, correlation between amounts of dATP in the two types of cells (r = 0.25,P > 0.1). The absolute peripheral lymphocyte count was correlated with the activity of ADA in circulating erythrocytes and with the response of lymphocytes to phytohemagglutinin (r = 0.64, P < 0.01; r = 0.49, P < 0.05). Response of lymphocytes to stimulation by phytohemagglutinin in vitro and absolute peripheral lymphocyte counts were not significantly correlated with levels of dATP in the erythrocyte or lymphocyte during periods of intensive therapy. Although there was objective improvement during enzyme replacement, the child remained immunodeficient and biochemically abnormal.
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PMID:Biochemical and functional abnormalities in lymphocytes from an adenosine deaminase-deficient patient during enzyme replacement therapy. 726 61

The activation of P2-receptors has a wide range of diverse effects in many tissues. Here we show that extracellular ATP stimulates lipogenesis in adipocytes derived from the epididymal fat pads of male Wistar rats. The lipogenic effect of ATP is not susceptible to treatment of adipocytes with adenosine deaminase or an adenosine receptor antagonist. Degradation of ATP in adipocyte suspension by ectonucleotidases is slow and remaining ATP concentrations are sufficient to activate P2-receptors. ATP does not affect basal or insulin stimulated glucose transport, or basal or isoproterenol stimulated lipolysis, respectively. The lipogenic effect of ATP is mimicked by the adenine compounds, ADP, AMP, and beta,gamma-methylene-ATP, but not by other nucleotides (UTP, UDP, CTP, GTP, ITP, and diadenosine tetraphosphate), indicating that extracellular nucleotides stimulate lipogenesis via a P2-receptor. ATP and its receptor may define a signalling system in adipocytes, which regulates fat stores independently from established hormones.
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PMID:Stimulation of lipogenesis in rat adipocytes by ATP, a ligand for P2-receptors. 1535 93

Pancreatic acini release ATP in response to various stimuli, including cholecystokinin octapeptide (CCK-8), as we show in the present study. There were indications that pancreatic juice also contains enzymes that could hydrolyze ATP during its passage through the ductal system. The aim of this study was to determine which ATP-degrading and possibly ATP-generating enzymes were present in pancreatic secretion. For this purpose, pancreatic juice was collected from anesthetized rats stimulated with infusion of CCK-8. Purine-converting activities in juice samples were assayed by TLC using either [gamma-(32)P]ATP or (14)C/(3)H-labeled and unlabeled nucleotides as appropriate substrates. Data show that the juice contains the enzyme ecto-nucleoside triphosphate diphosphohydrolase that can hydrolyze both [(14)C]ATP and [(3)H]ADP about equally well, i.e. CD39. Reverse-phase high-performance liquid chromatography analysis additionally shows that this enzyme has broad substrate specificity toward other nucleotides, UTP, UDP, ITP, and IDP. In addition, secretion contains ecto-5'-nucleotidase, CD73, further converting [(3)H]AMP to adenosine. Along with highly active hydrolytic enzymes, there were also ATP-generating enzymes in pancreatic juice, adenylate kinase, and NDP kinase, capable of sequentially phosphorylating AMP via ADP to ATP. Activities of nonspecific phosphatases, nucleotide pyrophosphatase/phosphodiesterases, and adenosine deaminase were negligible. Taken together, CCK-8 stimulation of pancreas causes release of both ATP-consuming and ATP-generating enzymes into pancreatic juice. This newly discovered richness of secreted enzymes underscores the importance of purine signaling between acini and pancreatic ducts lumen and implies regulation of the purine-converting enzymes release.
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PMID:ATP-consuming and ATP-generating enzymes secreted by pancreas. 1688 59


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