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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)

The activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid phosphatase, alkaline phosphatase and nucleotide pyrophosphatase was assayed in human thyroid glands. The 5'-nucleotidase activity was higher than that of AMP deaminase which suggested that AMP undergoes degradation primarily as a result of dephosphorylation in thyroid tissue. A high acid phosphatase activity was noted as compared to that of alkaline phosphatase activity. In toxic goitre the increase in adenosine deaminase and acid phosphatase was observed together with the decrease in pyrophosphatase activity.
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PMID:Activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid and alkaline phosphatase and nucleotide pyrophosphatase in human thyroid. 300 51

Activities of adenylate-degrading enzymes in muscles of vertebrates and invertebrates were determined. Mammalian and fish muscles showed a markedly higher activity of AMP deaminase with a lower level of adenosine deaminase and 5'-nucleotidase. Cephalopods showed an active adenosine deaminase and a 5'-nucleotidase which preferred AMP as the substrate. Negligible deamination of AMP and adenosine and little phosphohydrolase activity toward AMP and IMP were observed in the shellfish muscles. Adenine nucleotides can be degraded to form IMP via the AMP deaminase reaction in vertebrate muscles, while dephosphorylation of AMP to adenosine, which is then converted to inosine, appears to proceed in cephalopods. Adenylates can be hardly degraded in shellfish muscles.
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PMID:Activities of adenylate-degrading enzymes in muscles from vertebrates and invertebrates. 303 Jun 25

High-performance liquid chromatography analysis of acid-extracted tissues revealed decreases of high-energy nucleotides and increases in low-energy nucleotides and metabolites in heart, diaphragm, and liver but not in kidneys of diabetic rats. In comparison with nondiabetic rats, the total adenine nucleotide content of diabetic rat heart and diaphragm but not liver decreased, indicating an increase in catabolism of AMP. Maximal initial rates of the AMP catabolic enzymes 5'-nucleotidase, adenosine deaminase, and AMP deaminase were elevated in the hearts of BB/Wistar and streptozocin-induced diabetic rats. Nucleotide salvage enzymes adenylosuccinate synthetase and adenylosuccinate lyase were elevated above normal in the diabetic heart, whereas hypoxanthine-guanine phosphoribosyl transferase was not altered. Cytosolic-to-mitochondrial ratios from maximal initial rates after correction for mitochondrial breakage were increased above controls in diabetic hearts for nucleoside diphosphokinase and aspartate aminotransferase. Nucleotide levels, degradation rates, and substrate compartmentation between cytosol and mitochondria are discussed in relation to concurrent diabetes.
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PMID:Adenine nucleotide metabolism in hearts of diabetic rats. Comparison to diaphragm, liver, and kidney. 336 Feb 19

Long-term bovine lymphocyte cultures were initiated by stimulation with alloantigens and maintained in continuous culture using medium containing recombinant human interleukin-2 (rh IL-2). The development of specific and lectin-dependent killing was monitored following primary alloantigen challenge. Cytolytic activity was barely detectable after 7 days of culture, but gradually increased with peak activity occurring after 21 days of culture. A panel of monoclonal antibodies (MoAb) was used to determine whether a shift in the antigen phenotype of the cell population occurred during culture. The primary cell type that grew in culture was of the T-cell lineage with minimal or no expression of class II antigens. The activities of adenosine deaminase (ADA), purine nucleotide phosphorylase (PNP), adenosine kinase (AK), deoxyadenosine kinase (dAK), deoxycytidine kinase (dCK), 5'-nucleotidase (5'-N), AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase (HGPRT or HPRT), and adenine phosphoribosyl transferase (APRT) were measured by microassay in resting peripheral blood lymphocytes (PBL) and in cells from long-term cultures. Large increases in the activities of PNP and HPRT with a decrease in the activity of ADA were observed. The data show that long-term cultures of lymphocytes can be readily generated, and that sequential changes in antigenic phenotype and function can be monitored and correlated with quantitative changes in enzyme activity.
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PMID:Development and maintenance of bovine cytotoxic lymphocytes with recombinant human interleukin-2. 348 20

The synthesis and characterization of 8-amino-6-fluoro-9-beta-D-ribofuranosyl-9H-purine (3a) are presented. This compound is a substrate for adenosine deaminase and adenosine kinase. In L1210 cells 3a is converted to 8-aminoinosine monophosphate (4b), apparently by the action of AMP deaminase on the monophosphate of 3a, as well as to the triphosphate derivative of 3a. Pentostatin was used to inhibit adenosine deaminase, and coformycin was used to inhibit AMP deaminase in experiments designed to delineate the metabolic fate of 3a. Pentostatin was without influence on the cytotoxicity of 3a, but coformycin potentiated the cytotoxicity. The potentiation was associated with an increased cellular concentration of phosphates of 3a and a decreased concentration of 4b.
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PMID:Synthesis and biochemical properties of 8-amino-6-fluoro-9-beta-D-ribofuranosyl-9H-purine. 348 38

1. AMP catabolism in frog liver extract was found to proceed exclusively through the formation of IMP. Further metabolism of IMP is relatively slow. 2. Among the enzymes involved in AMP catabolism, AMP deaminase is most active and adenosine deaminase and AMP 5'-nucleotidase exhibit only 20 and 10% of AMP deaminase activity respectively.
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PMID:Adenosine-5-monophosphate catabolism in frog liver. 349 71

Neplanocin A and aristeromycin are carbocyclic adenosine analogs that differ only in that neplanocin A contains a double bond in the carbocyclic ring, whereas this ring in aristeromycin is saturated. We have compared the metabolism and some of the metabolic effects of neplanocin A and synthetic (+/-)-aristeromycin (C-Ado) in murine leukemia L1210 cells in culture. C-Ado, as shown earlier, was not only converted to its own phosphates but also was metabolized to phosphates of carbocyclic guanosine. Both rapidly proliferating and slowly proliferating or resting cells phosphorylated C-Ado, but C-Ado was not converted to phosphates of carbocyclic guanosine in detectable amounts in cells whose growth had reached a plateau. When the metabolism of neplanocin and C-Ado was examined in the same experiment, both analogs were converted to the triphosphate analogs of ATP; no conversion of neplanocin A to the corresponding carbocyclic analogs of guanine nucleotides was detected, whereas C-Ado was converted to the carbocyclic analog of GTP in amounts that approximated the GTP pool. This difference in metabolism was associated with a marked difference in effects of the two analogs on the utilization of hypoxanthine and guanine which was inhibited by C-Ado but not by neplanocin. The failure of neplanocin A to be converted to analogs of guanine nucleotides apparently is the result of poor capacity of its monophosphate to serve as a substrate for AMP deaminase; the Vmax for deamination of neplanocin-5'-monophosphate by this enzyme was only 5% of that for C-Ado monophosphate. In contrast, neplanocin A was a better substrate than C-Ado for adenosine deaminase.
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PMID:Differences in the metabolism and metabolic effects of the carbocyclic adenosine analogs, neplanocin A and aristeromycin. 370 57

Ordinarily packaged in DNA, adenine deoxyribonucleotides are preferentially concentrated in erythrocyte and lymphocyte cytosol in adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) deficiency. A spectrum of cytosol enzyme activities are defined in terms of reaction velocities, K0.5s, and nucleotide partition after incubation with ribo- and deoxyribonucleotides. AMP and dAMP were dephosphorylated, but only AMP was deaminated in vitro. Although nucleotidase activity is much stronger in lymphocytes, AMP deaminase was the dominant degradative reaction in all erythrocyte and lymphocyte lysates under the conditions specified. For most cytosolic enzymes, ribonucleotides were preferred cofactors, implying that dADP and dATP often may be bystanders at metabolic events. The adenylate kinase-mediated partition of approximately equimolar ribo- and deoxyribonucleotide substrates yielded a very large preponderance of AMP in the monophosphate compartment, the monophosphates alone being directly vulnerable to degradative loss. The adenylate kinase(s) of lymphocytes differed strikingly from those of erythrocytes in reaction velocities with nucleotide cofactors, K0.5s, and in susceptibility to substrate inhibition.
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PMID:Adenine ribo- and deoxyribonucleotide metabolism in human erythrocytes, B- and T-lymphocyte cell lines, and monocyte-macrophages. 386 21

The exact pathway whereby the initial catabolism of the adenine nucleotides proceeds from AMP and the possibility of a recycling of adenosine were investigated in human erythrocytes. Adenine nucleotide catabolism, reflected by the production of hypoxanthine, is very slow under physiologic conditions and can be greatly increased by suppression of glucose or alkalinization of the medium. Experiments with inhibitors of adenosine deaminase and adenosine kinase demonstrated that under physiologic conditions the initial catabolism of AMP proceeds by way of a deamination of AMP, followed by dephosphorylation of inosine monophosphate, and that no recycling occurs between AMP and adenosine. Under glucose deprivation, approximately 75% of the 20-fold increase of the catabolism of the adenine nucleotides proceeded by way of a dephosphorylation of AMP followed by deamination of adenosine, and a small recycling of this nucleoside could be evidenced. Inhibition of adenosine transport showed that the dephosphorylation of AMP occurred intracellularly. When the incubation medium was alkalinized in the presence of glucose, the 15-fold increase in the conversion of AMP to hypoxanthine proceeded exclusively by way of AMP deaminase but a small recycling of adenosine could also be evidenced. The threefold elevation of intraerythrocytic inorganic phosphate (Pi) during glucose deprivation and its 50% decrease during alkalinization as well as experiments in which extracellular Pi was modified, indicate that the dephosphorylation of red blood cell AMP is mainly responsive to variations of AMP, whereas its deamination is more sensitive to Pi.
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PMID:Pathways of adenine nucleotide catabolism in erythrocytes. 394 80

The activities of 5'-nucleotidase (5'-ribonucleoside phosphohydrolase, EC 3.1.3.5); adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4); AMP deaminase (AMP aminohydrolase, EC 3.5.3.6), and ATP-(Mg2+)-ase (ATP phosphohydrolase, EC 3.6.1.3) were assayed in mitochondria of normal and regenerating rat liver 5'-Nucleotidase (5'Nase) and ATP-(Mg2+)-ase activities were compared with similar enzyme activities in the plasma membrane (PM) fraction, obtained from the same biological material. In the regenerating liver, 5'Nase for dTMP diminished its activity by 56% (24 h after partial hepatectomy) and 35 +/- 4% for all substrates in the PM fraction (48 h after operation). In mitochondria, 5'Nase for dTMP manifests sigmoidal substrate activity curve (in contrast with all substrates in the PM fraction and remaining substrates in mitochondria). In vivo 5-azacytidine (a) administered 1 h after partial hepatectomy, prevented changes of 5'Nase activity: (b) administered 24 or 48 h after partial hepatectomy, stabilized low 5'Nase activity (in mitochondria for dTMP, in the PM fraction for all substrates) and decreased ATP-(Mg2+)-ase activity by 51 and 31% in mitochondria and the PM fraction respectively.
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PMID:A distinctive activity of 5'-nucleotidase for dTMP in rat liver mitochondria. 615 75


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