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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

5'-Nucleotidase, adenosine phosphorylase, adenosine deaminase and purine nucleoside phosphorylase, four enzymes involved in the utilization of exogenous compounds in Bacillus cereus, were measured in extracts of this organism grown in different conditions. It was found that adenosine deaminase is inducible by addition of adenine derivatives to the growth medium, and purine, nucleoside phosphorylase by metabolizable purine and pyrimidine ribonucleosides. Adenosine deaminase is repressed by inosine, while both enzymes are repressed by glucose. Evidence is presented that during growth of B. cereus in the presence of AMP, the concerted action of 5'-nucleotidase and adenosine phosphorylase, two constitutive enzymes, leads to formation of adenine, and thereby to induction of adenosine deaminase. The ionsine formed would then cause induction of the purine nucleoside phosphorylase and repression of the deaminase. Taken together with our previous findings showing that purine nucleoside phosphorylase of B. cereus acts as a translocase of the ribose moiety of inosine inside the cell (Mura, U., Sgarrella, F. and Ipata, P.L. (1978) J. Biol Chem. 253, 7905-7909), our results provide a clear picture of the molecular events leading to the utilization of the sugar moiety of exogenous AMP, adenosine and inosine as an energy source.
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PMID:Induction and repression of enzymes involved in exogenous purine compound utilization of Bacillus cereus. 627 19

The effect of isoproterenol perfusion on cAMP levels and phosphorylase activity was investigated in the spontaneously hypertensive rat (SHR) and Kyoto Wistar normotensive control rat (WKY) heart. The basal force of contraction in physiological salt solution perfused hearts was comparable between SHR and WKY. However, the force of contraction in response to 10 nM isoproterenol perfusion was decreased approximately 20-30% in SHR heart as compared to WKY heart. Basal cAMP levels were reduced in SHR hearts as compared to WKY hearts. Isoproterenol perfusion resulted in an increase in cAMP levels over the basal cAMP values which was 50% and 100% in SHR and WKY hearts, respectively. Basal phosphorylase activity was higher in SHR hearts as compared to WKY hearts. However, the percentage increase in phosphorylase activity by isoproterenol perfusion over the basal values was approximately 400% in WKY hearts and only 200% in SHR hearts. The ouabain-sensitive (Na+, K+)-ATPase activity, Ca2+ binding in the absence of ATP, sialic acid content, and 5'-nucleotidase activity of purified cardiac plasma membranes was not altered in SHR as compared to WKY. These results would suggest beta-adrenergic mediated adenylate cyclase stimulation is decreased in SHR myocardium while other plasma membrane properties and associated enzymes may not be altered.
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PMID:Reduced cAMP levels and glycogen phosphorylase activation in isoproterenol perfused SHR myocardium. 631 20

Lymphocyte populations of BALB/c mice were obtained from bone marrow, thymus, spleen, peripheral blood and lymphoid nodes. Subpopulations of thymocytes and bone marrow T-lymphocyte precursors were separated by density gradient centrifugation. The activity of adenosine deaminase (ADA) undergoes a marked increase during the evolution of bone marrow T-cell precursors to immature thymocytes, and a decrease with thymocytes maturation. The peripheral blood lymphocytes (PBL) present the lower activity of the enzyme, and lymphocytes from spleen (SL) and lymphoid nodes (LNL) show activity in the order of that in mature thymocytes. The activity of purine nucleotide phosphorylase (PNP) in the different lymphocytes populations experiments a very little variation with the T-lymphocyte differentiation. With the evolution of T-lymphocyte precursors to immature thymocytes the 5'-nucleotidase (5'-NT) activity experiment a 2-fold decrease. The thymocytes maturation is correlated with an increase in the activity of 5'-NT. The PBL present the maximal activity of the enzyme, whereas in spleen and LNL its levels of activity are in the range of that in mature thymocytes and bone marrow T-cell precursors respectively.
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PMID:The distribution of adenosine deaminase, purine nucleotide phosphorylase and 5'-nucleotidase in subpopulations of thymocytes, bone marrow cells and other lymphoid organs in mice. 632 33

The present work describes an assay which is highly specific for ribose-5-phosphate. The method is based on the following three-stage enzymatic conversion: (1) ribose 5-phosphate in equilibrium ribose 1-phosphate (phosphopentomutase); (2) ribose 1-phosphate + adenine in equilibrium adenosine + Pi (adenosine phosphorylase); (3) adenosine + H2O----inosine + NH3 (adenosine deaminase). Ribose 5-phosphate may be determined either directly following the change in absorbance at 265 nm associated with the conversion of adenine to inosine, or radioenzymatically by measuring the radioactivity of inosine formed from [8-14C]adenine, after chromatographic separation of the nucleoside on polyethyleneimine-cellulose. The spectrophotometric assay was used to follow ribose 5-phosphate formation and ribose 1-phosphate consumption catalyzed by phosphopentomutase. Further, the ability of alkaline phosphatase, 5'-nucleotidase and crude extract of Bacillus cereus cells to act on ribose 5-phosphate was tested. The radioenzymatic assay was proved useful in determining the levels of ribose 5-phosphate in rat tissues.
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PMID:Spectrophotometric and radioenzymatic determination of ribose-5-phosphate. 653 May 7

Homogenates of the posterior latissimus dorsi muscle, a phasic muscle, were fractionated by a one-step zonal centrifugation technique into four major organelle populations and cytoplasmic constituents. These were: (1) Plasma membrane fragments with a modal equilibrium density of 1.10 and containing 5'-nucleotidase, alkaline phosphodiesterase, p-nitrophenylphosphatase and acid phosphatase (beta-glycerophosphate was used as the substrate). (2) Sarcoplasmic reticular fragments which could be further subdivided into calcium transport vesicles, with a model equilibrium density of 1.16, that exhibited calcium uptake; K+-ATPase; leucyl-bet-naphthylamidase; acid phosphodiesterase; acid phosphatase (using cytidine monophosphate as the substrate); and sarcoplasmic reticular lysosomes, with a model equilibrium density of 1.18, possessing dipeptidyl-aminopeptidase II, cathepsin D, alpha-glucosidase, N-acetyl-beta-glucosaminidase, and NADH oxidase activity. (3) Mitochondria with a modal equilibrium density of 1.21. (4) Catalase-containing vesicles with a modal equilibrium density of 1.22; and cytoplasmic constituents (modal density of 1.25) with phosphorylase, pyruvate kinase, myosin-ATPase, aldolase, and protein and RNA content. The purity of these organelles was equal to or better than previous efforts, with a 30-fold purification achieved for 5'-nucleotidase and alkaline phosphodiesterase. These results lend support to the hypothesis that the sarcoplasmic reticulum of phasic muscle, in addition to its specialized role in excitation-contraction coupling, represents a multifunctional membrane system, and that, similar to the smooth endoplasmic reticulum of other cells, it includes some membrane-bound lysosomal enzymes and NADH oxidase.
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PMID:Isopycnic-zonal centrifugation of plasma membrane, sarcoplasmic reticular fragments, lysosomes, and cytoplasmic proteins from phasic skeletal muscle. 721 87

Viable and homogeneous endothelial cells were obtained from isolated guinea pig hearts by application of a special perfusion technique of the coronary system with an isotonic collagenase-trypsin solution and subsequent purification of the dissociated cells by Percoll density gradient centrifugation. The coronary endothelial cells were grown in tissue culture for periods up to 7 months. Serial passage proved to be possible. During logarithmic growth, generation time was found to be 18 h; it could be reduced to 16 h by addition of thrombin to the culture medium. Light, phase contrast and scanning electron microscopy as well as autoradiography revealed that cultured coronary endothelial cells grew as strict monolayers of closely apposed, polygonal large cells. By scanning electron microscopy, it could be demonstrated that the morphology of the cultured cells changes characteristically during attachment of the cells to their substratum. The changes observed were very similar to those of proliferating endothelial cells of isolated coronary vessels kept in organ culture. According to transmission electron microscopy studies, cultured coronary endothelial cells proved to contain only an extremely small number of Weibel-Palade bodies. Nucleoside phosphorylase (EC 2.4.2.5.) and 5'-nucleotidase (EC 3.1.3.5.) were identified in freshly isolated as well as in cultured endothelial cells. Their specific and total activities proved to be much higher than in myocardial tissue, thus indicating a prominent role of nucleotide metabolism in the coronary endothelium.
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PMID:Isolation, identification, and continuous culture of coronary endothelial cells from guinea pig hearts. 728 45

Because adenosine has an antiadrenergic action in the heart, young (3-4 mo) and aged (18-20 mo) adult Sprague-Dawley and Fischer 344 rat hearts were perfused to determine whether interstitial adenosine plays a role in the reduced metabolic and mechanical responsiveness of the aged heart to beta-adrenergic stimulation. Interstitial adenosine was approximately twofold greater in aged hearts compared with young adult hearts, and 10(-8) M isoproterenol (ISO) further increased these levels. ISO increased myocardial adenosine 3',5'-cyclic monophosphate content, glycogen phosphorylase activity, and cardiac contractility by 83, 150, and 130%, respectively, in young hearts but only increased these variables by 45, 74, and 61%, respectively, in aged hearts. Sulfophenyl-theophylline prevented the reduced ISO-induced responsiveness of the above variables in aged hearts. Exogenously administered adenosine deaminase eliminated the reduced ISO-induced contractile responsiveness in aged hearts. The apparent activities of 5'-nucleotidase and adenosine deaminase were not significantly different in ventricular samples from young and aged hearts. These results suggest that the elevated interstitial level of adenosine exerts a greater antiadrenergic effect in the aged heart, rendering it less responsive to beta-adrenergic stimulation. The increased interstitial level of adenosine in the aged heart does not appear to be due to a difference in the activities of either 5'-nucleotidase or adenosine deaminase.
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PMID:Adenosine inhibition of beta-adrenergic induced responses in aged hearts. 810 39

In the present study we have investigated whether enzyme histochemical parameters can be applied to detect early ischemic damage in rat heart after ischemia without restoration of the blood flow. Ischemia was induced by incubating heart fragments for 0, 10, 20, 30, 60, 120 and 240 min at 37 degrees C. The activity and localization of the following enzymes was studied in unfixed cryostat sections using quantitative histochemical methods: lactate dehydrogenase, creatine kinase, succinate dehydrogenase, phosphofructokinase, acid phosphatase, 5'-nucleotidase and glycogen phosphorylase. Moreover, the ultrastructure of the tissue was studied with special attention to the appearance of flocculent densities in mitochondria, which can be seen as a sign of irreversible cell damage. It was shown that glycogen phosphorylase activity in rat heart decreased after short periods (30 min) of in vitro ischemia, whereas all other enzymes studied were not decreased up to 240 min, with the exception of lactate dehydrogenase and phosphofructokinase activities which were diminished only at 240 and 120 min of ischemia, respectively. Some reaction product was found after incubating for 5'-nucleotidase activity in the absence of substrate, indicating the presence of endogenous substrate(s). This endogenous substrate disappeared from the myocytes after 20 min of ischemia. It is assumed that AMP and/or other phosphate-containing compounds play an essential role in the activation of glycogen phosphorylase. Significant reduction of glycogen phosphorylase activity is correlated with the irreversible stage of damage of myocytes as judged from the ultrastructure.
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PMID:Histochemical detection of glycogen phosphorylase activity as parameter for early ischemic damage in rat heart. 850 31

The mechanisms and myocardial alterations associated with NO-deficient hypertension are still far from clear. The aim of the present study was to focus on the enzyme histochemical and subcellular changes in the heart of L-NAME treated rats, as well as to examine the influence of captopril treatment. Wistar rats were administered either L-NAME (40 mg/kg/day) alone or together with captopril (100 mg/kg/day) for a period of 4 weeks. A significant increase of blood pressure confirmed the reliability of the model. The results showed that long-lasting L-NAME administration was accompanied by a decrease of endothelial NO-synthase activity and by a significant local decrease of the following enzyme activities: capillary-related alkaline phosphatase, 5'-nucleotidase and ATPase (but not dipeptidyl peptidase IV) and cardiomyocyte-related glycogen phosphorylase, succinic dehydrogenase, beta-hydroxybutyrate dehydrogenase and ATPases. No activity of these enzymes was found in the scar, whereas a marked increase of alkaline phosphatase and dipeptidyl peptidase IV activities was found in the foci of fibrotization. Histochemical changes correlated with subcellular changes, which were characterized by 1) apparent fibroblast activation associated with interstitial/perivascular fibrosis, 2) heterogeneous population of the normal, hypertrophic and injured cardiomyocytes, 3) enhancement of the atrial granules and their translocation into the sarcolemma, and 4) impairment of capillaries as well as by induction of angiogenesis. Similar alterations were also found in the heart of captopril co-treated rats, despite of the significant suppression of blood pressure. The results indicate that NO-deficient hypertension is accompanied by metabolic disturbances and ultrastructural alterations of the heart and these changes are probably not induced by the renin-angiotension system only.
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PMID:Chronic disturbances in NO production results in histochemical and subcellular alterations of the rat heart. 1080 8

Recent advances in cytokinin analysis have made it possible to measure the content of 22 cytokinin metabolites in the tissue of developing tobacco seedlings. Individual types of cytokinins in plants are interconverted to their respective forms by several enzymatic activities (5'-AMP-isopentenyltransferase, adenosine nucleosidase, 5'-nucleotidase, adenosine phosphorylase, adenosine kinase, trans-hydroxylase, zeatin reductase, beta-glucosidase, O-glucosyl transferase, N-glucosyl transferase, cytokinin oxidase). This paper reports modelling and measuring of the dynamics of endogenous cytokinins in tobacco plants grown on media supplemented with isopentenyl adenine (IP), zeatin (Z) and dihydrozeatin riboside (DHZR). Differences in phenotypes generated by the three cytokinins are shown and discussed, and the assumption that substrate concentration drives enzyme kinetics underpinned the construction of a simple mathematical model of cytokinin metabolism in developing seedlings. The model was tested on data obtained from liquid chromatography/tandem mass spectrometry cytokinin measurements on tobacco seedlings grown on Murashige and Skoog agar nutrient medium, and on plants grown in the presence of IP, Z and DHZR. A close match was found between measured and simulated data, especially after a series of iterative parameter searches, in which the parameters were set to obtain the best fit with one of the data sets.
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PMID:Dynamics of endogenous cytokinin pools in tobacco seedlings: a modelling approach. 1264 3


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