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)

Immunological and biochemical studies of spontaneously metastasizing and nonmetastasizing rat mammary carcinomas and their plasma membranes indicated that: (i) all spontaneously metastasizing tumors have little or no demonstrable glycocalyx, while all nonmetastasizing tumors have a thick glycocalyx; (ii) there is a direct relationship between the glycocalyx and immunogenicity, and an inverse relationship with the metastasizing capacity of tumor cells, properties which can be quantitated by levels of the plasma membrane marker enzyme 5'-nucleotidase (EC3.1.3.5;5'-ribonucleotide phosphohydrolase) activity; (iii) the absence of glycocalyx from the metastasizing tumor cell surface seems to result from its dissociation from plasma membranes, for solubilized cell surface antigen is readily found in the blood of metastasizing tumor bearing rats, while there was no detectable tumor cell surface antigen in the blood of the nonmetastasizing tumor hosts tested; (iv) both metastasizing and nonmetastasizing mammary tumors appear to have a common soluble cell surface antigen; (v) in addition to this common antigen, there is another membrane-bound antigen in the nonmetastasizing, immunogenic tumor cell surface which presumably is the tumor specific transplantation antigen; and (vi) this antigen is immunobiologically unique, but seems to be immunochemically related to the common soluble antigen. It is postulated that the lack of an immunogenic coat and/or the presence of solubilized tumor cell surface antigen in the blood may provide an immune escape mechanism for tumor cells by interfering with cell-mediated immune response of tumor hosts, leading to their dissemination.
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PMID:Immunological escape mechanism in spontaneously metastasizing mammary tumors. 4 47

A new species of orthophosphate repressible extracellular 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) was found to be released into mycelial culture media when a wild type strain of Neurospora crassa was grown on limiting amounts of phosphate. The production of 5'-nucleotidase and extracellular acid and alkaline phosphatase was inhibited by the addition of rifampicin when it was added at the later stage of mycelial growth, but not when it was added at a very early stage. The 5'-nucleotidase and extracellular alkaline phosphatase were partially purified and characterized. pH optimum of the former was 6.8 and that of the latter was higher than 10.0. The 5'-nucleotidase activity was inhibited by ethylenediaminetetraacetate (EDTA) and ZnCl2 at pH 6.8 and stimulated by MnCl2 and CoCl2 at pH 4.0. Alkaline phosphatase activity was stimulated by EDTA, MgCl2, CoCl2 and MnCl2. 5'-nucleotidase activity was stimulated by EDTA, MgCl2, CoCl2 and MnCl2. 5'-nucleotidase hydrolyzed various 5'-nucletides but not 3'-nucleotides or other various phosphomono- and diester compounds. Alkaline phosphatase hydrolyzed all the phosphomonoester compounds tested. Mutants, nuc-1 and nuc-2, which were originally isolated by the inability to utilize RNA or DNA as a sole source of phosphate, were unable to produce 5'-nucleotidase or six other repressible enzymes reported previously. These mutants showed no or significantly reduced growth on orthophosphate-free nucleotide media depending on the number of conidia inoculated, mainly because of loss of ability to produce these repressible extracellular phosphatases.
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PMID:Control of the production and partial characterization of repressible extracellular 5'-nucleotidase and alkaline phosphatase in Neurospora crass. 13 48

The amount of HL-A antigens present on the peripheral blood lymphocytes of a single human donor was increased about 11-fold after stimulation with phytohemagglutinin and 36-fold after transformation with Epstein-Barr virus. This increase applied to all four HL-A specificities of these cells. The response to phytohemagglutinin was dependent on dose and was first observed at 12 hr of incubation. Measurements of the amount of surface membranes by geometry, by radioiodinatable surface proteins, and by 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) assay all indicated that the enhanced representation of HL-A antigens after stimulation by phytohemagglutinin or transformation by Epstein-Barr virus must be due to an increase in the density of these antigens on the cell surface.
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PMID:Enhanced representation of HL-A antigens on human lymphocytes after mitogenesis induced by phytohemagglutinin or Epstein-Barr virus. 17 57

Deoxyadenosine metabolism was investigated in cultured human cells to elucidate the biochemical basis for the sensitivity of T lymphoblasts and the resistance of B lymphoblasts to deoxyadenosine toxicity. T lymphoblasts have a 20-to 45-fold greater capacity to synthesize deoxyadenosine nucleotides than B lymphoblasts at deoxyadenosine concentrations of 50--300 micron. During the synthesis of dATP, T lymphoblasts accumulate large quantities of dADP, whereas B lymphoblasts do not accumulate dADP. Enzymes affecting deoxyadenosine nucleotide synthesis were assayed in these cells. No substantial differences were evident in activities of deoxyadenosine kinase (ATP: deoxyadenosine 5'-phosphotransferase, EC 2.7.1.76) or deoxyadenylate kinase [ATP:(d)AMP phosphotransferase, EC 2.7.4.11]. The activity of 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) was increased 44-fold for AMP and 7-fold for dAMP in B lymphoblasts. A model for the regulation of deoxyadenosine nucleotide synthesis by 5'-nucleotidase activity is proposed on the basis of the observations.
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PMID:Biochemical basis for differential deoxyadenosine toxicity to T and B lymphoblasts: role for 5'-nucleotidase. 22 24

Pyrimidine 5'-nucleotidase (P5N, EC 3.1.3.5) appears to be a sensitive index of exposure to low level lead. In 21 children 2 to 5 years old with blood leads of 7 to 80 micrograms/dl there was a negative linear correlation of blood lead and red cell P5N: r = -0.60 (P less than 0.01), Y = -0.11X + 12.3. In rats, the enzyme assay was quantitatively similar to that of the human. A treatment group of 12 rats received lead acetate, 36 mg/kg/day, of lead as 0.17 M lead acetate for 24 days. The blood lead of treated rats increased from the control value of 8.3 +/- 1.3 to 36.0 +/- 0.5 on day 24; P5N decreased from 18.3 +/- 0.8 units to 9.0 +/- 1.0 and was below control values at a blood lead of 25. There was a significant negative linear correlation of blood lead and P5N: r = -0.85; n = 17; P less than 0.001; Y = 0.34X + 20.9 that was independent of the correlationship with the reticulocytes. At these levels of blood lead and P5N there was no significant change in the hexokinase, hemoglobin or red cell count and no evidence of stippling.
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PMID:Low level lead and inhibition of erythrocyte pyrimidine nucleotidase. 23 17

A procedure is presented for the rapid purification of a 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) from potato tubers, involving ammonium sulphate fractionation and chromatography on phosphocellulose, DEAE-cellulose and Sephadex G-75. Application of this procedure results in a 6000-fold purification of the 5'-nucleotidase and the final preparations are virtually homogeneous, yielding only one protein band on electrophorsis in polyacrylamide gels in non-dissociating or dissociating conditions. The 5'-nucleotidase has a molecular weight of 50 000 from gel filtration experiments. Sodium dodecylsulphate-polyacrylamide gel electrophoresis of the purified 5'-nucleotidase reveals one major band of molecular weight 25 000. The 5'-nucleotidase is competitively inhibited by cyclic nucleotides, having micromolar Ki values for cyclic AMP and cyclic GMP at pH 5.0 and pH 8.0. The enzyme has a pH optimum of 5.0 with 5'-GMP as substrate. While 5'-AMP and 3'-AMP are hydrolyzed at comparable rates at pH 5.0, at pH 8.0 the rate of hydrolysis of 3'-AMP is only 4% of that with 5'-AMP. ADP, ATP and 2'-AMP are very poor substrates for the enzyme. The nucleotidase has micromolar Km values for nucleoside 5'-monophosphates other than 5'-NMP. A wide variety of divalent cations activate the 5'-nucleotidase.
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PMID:Purification and characterization of a cyclic nucleotide-regulated 5'-nucleotidase from potatoe. 23 99

Low activity of 5'-nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) in T lymphoblasts may explain the marked sensitivity of this cell to deoxynucleotide accumulation when compared to B lymphoblasts. The relevance of such observations with cultured cells to the normal immune system requires the demonstration of similar differences in the 5'-nucleotidase activity of normal human lymphocyte subpopulations. Sheep erythrocyte (E) rosette-forming cells from normal thymus, tonsil, and peripheral mononuclear cells have 5'-nucleotidase activities of 1.7, 11.3, and 21.2 nmol/hr per 10(6) cells. Non-E-rosette forming cells from the peripheral blood or tonsil have 5'-nucleotidase activity comparable to the higher levels found in the peripheral E-RFC. Increased levels of 5'-nucleotidase activity may be a marker for post-thymic T lymphocytes. T lymphoblasts have 5'-nucleotidase activity similar to values demonstrated for E-RFC in thymus, whereas cultured B lymphoblasts have 5'-nucleotidase activity 15 times greater than that of T lymphoblasts. On the basis of these observations, the 5'-nucleotidase deficiency in congenital agammaglobulinemia has been reevaluated. In these patients the data indicate that peripheral E-rosette forming cells have the enzyme deficiency, demonstrating an abnormality of T lymphocytes in this disorder of immunoglobulin production.
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PMID:Distribution of 5'-nucleotidase in human lymphoid tissues. 31 65

For the determination of 5'-ribonucleotide phosphohydrolase (EC 3.1.3.5;5'-Nase) in rat liver, a radiochemical double-labelling assay was developed. [14C]-labelled AMP which is hydrolyzed to [14C]-adenosine by 5'-Nase activity is added to crude liver homogenates. After 30 min, the process is stopped and [2-3H]-adenosine added to estimate the loss of [14C]-adenosine during separation by ion exchange column chromatography. The enzymatic reaction was found to be linear in correlation with the enzyme content and the incubation time. The specificity of the reaction was evaluated by addition of beta-glycerophosphate which acts as a competitive inhibitor to eliminate the catalytic effect of non-specific phosphatases, and addition of alpha, beta-methylene adenosine 5'-diphosphate, a specific inhibitor of 5'-Nase; both cause an almost complete suppression of enzyme activity.
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PMID:A double-labelling radioassay for the determination of 5'-nucleotidase activity. 45 39

1. 5'-Nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) from the cytosol of chicken liver has been purified 1860-fold with an overall yield of 20% by a combination of precipitation at pH 5.3, (NH4)2SO4 fractionation, calcium phosphate gel adsorption, phosphocellulose chromatography and gel filtration with Sephadex G-200. The enzyme has been shown to be highly purified, as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. This is the first time it has been possible to obtain a purified 5'-nucleotidase from the cytosol of animal tissue. 2. An S20, W of 9.7 S for 5'-nucleotidase was obtained by the use of sucrose density gradient centrifugation and a Stokes radius of 5.1 nm was estimated by gel filtration techniques. From these values and the assumed partial specific volume of 0.725 cm3/g, the molecular weight of the enzyme was calculated to be 205 000. One major band, corresponding to a molecular weight of 51 000, was detected after sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicating that the native enzyme was composed of four identical subunits. 3. Some properties of the purified enzyme, including pH optimum Mg2+ dependency and substrate specificity, resembled closely those of the partially purified enzyme from chicken liver acetone powder as reported by Itoh, R., Mitsui, A. and Tsushima, K. (1967) Biochim. Biophys. Acta 146, 151-159.
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PMID:Cytosol 5'-nucleotidase from chicken liver. Purification and some properties. 94 52

Hepatic 5'-nucleotidase (EC 3.1.3.5; 5'-ribonucleotide phosphohydrolase) activity has been studied in cisternal elements of the Golgi complex and in secretion vacuoles, both isolated after ethanol administration to rats in vivo. The enzyme in secretion vacuoles was latent, so that a 5-fold increase in activity was observed when incubations were carried out in the presence of detergent; evidence is presented that the latency is caused by the impermeability of the membrane to substrate. Essentially no latency was observed in Golgi cisternae. Confirming the results of Farquhar et al. [(1974) J. Cell Biol. 60, 8-25], reaction product from 5'-nucleotidase was localized by cytochemical procedures on the inside of secretion vacuoles and on the cytoplasmic side of Golgi cisternae. After solubilization in detergent, the enzyme from both fractions reacted almost identically with both antibody to the purified enzyme and concanavalin A. In contrast, when intact fractions were incubated with an excess of antibody or concanavalin A, only 22-23% of the enzyme was inhibited in secretion vacuoles whereas 51-84% was inhibited in Golgi cisternae. Sonication of secretion vacuoles in the presence of antibody or concanavalin A increased the inhibition 2- to 3-fold. It is suggested that during the formation of secretion vacuoles from the Golgi cisternae, 5'-nucleotidase is translocated from the cytoplasmic side of the membrane to the inside.
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PMID:Evidence for the translocation of 5'-nucleotidase across hepatic membranes in vivo. 106 84


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