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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)

The transformation of inosine into 5'-inosine acid by Pseudomonas trifolii cells was studied. The synthesis of 5'-inosine acid can be performed by both live intact and dry cells. The effectiveness of inosine phosphorylation depends on the ratio of the inosine and phosphate donor concentrations and the amount of cells. The temperature and pH effect on activity of nucleoside phosphotransferase, phosphomonoesterase and 5'-nucleotidase has been studied. The influence of surface active substances and metal ions on the synthesis of 5'-inosine acid has been investigated. Optimal conditions for the inosine transformation by the above culture have been established.
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PMID:[Study of inosine transformation into 5'-inosinic acid by the culture of Pseudomonas trifoli]. 0 21

The effects of fixation with various concentrations of glutaraldehyde or formaldehyde, acetone or ethanol, and freeze-drying on 5 phosphatases of Eimeria tenella and chick kidney cell cultures were demonstrated in situ. Gultaraldehyde inactivated the phosphatases more than did the formaldehyde, but the effect of the combination of the 2 (Karnovsky's fixative) was greater than that of either glutaraldehyde or formaldehyde alone. The higher the concentration of aldehyde and the longer the duration of exposure, the greater the inactivation. The order of sensitivity to aldehyde fixation of the enzymes tested was glucose-6-phosphatase greater than thiamine pyrophosphatase greater than 5'-nucleotidase greater than adenosine triphosphatase greater than acid phosphatase. Cytologic detail was preserved more efficiently with glutaraldehyde than with formaldehyde. Optimal preservation of enzyme activity for cytochemistry was with 2% glutaraldehyde for 30 min or 2% formaldehyde for 1 hr for G-6-Pase, TPPase, and 5'-nucleotidase, and with 2% glutaraldehyde or 2% formaldehyde for 2 hr with ATPase and AcPase. Quenching with subsequent fixation in cold acetone or ethanol resulted in complete inactivation of G-6-Pase, TPPase, and 5'-nucleotidase; although cells fixed in this manner yielded large amounts of reaction product for ATPase and AcPase, the distribution was diffuse, and some of it appeared to be artifactual. Quenching with subsequent freeze-drying was unsatisfactory because nearly all of the cell layers rolled off the cover glasses.
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PMID:Effect of fixation on demonstration of phosphatases of Eimeria tenella grown in chick kidney cell cultures. 6 Dec 71

Plasma membranes from KB cells were isolated by the method of latex bead ingestion and were compared with those obtained by the ZnCl(2) method. Optimal conditions for bead uptake and the isolation procedure employing discontinuous sucrose gradient centrifugation are described. All steps of preparative procedure were monitored by electron microscopy and specific enzyme activities. The plasma membrane fraction obtained by both methods is characterized by the presence of the Na(+) + K(+)-activated ATPase and 5'-nucleotidase, and contains NADPH-cytochrome c reductase and cytochrome b(5). The latter two enzymes are also present in lower concentrations in the microsomal fraction. Unlike microsomes which are devoid of the Na(+) + K(+)-activated ATPase and which contain only traces of 5'-nucleotidase activity, the plasma membrane fraction contains only trace amounts of the rotenone-insensitive NADH-cytochrome c reductase but no cytochrome P-450, both of which are mainly microsomal components. Morphologically the plasma membrane fraction isolated by the latex bead method is composed of vesicles of 0.1-0.3 microm in diameter. On the basis of the biochemical and morphological criteria presented, it is concluded that the plasma membrane fraction isolated by the above methods are of high degree of purity.
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PMID:Isolation and properties of the plasma membrane of KB cells. 428 30

1. Optimal assay conditions for two plasma membrane reference enzymes, alkaline phosphodiesterase 1 and 5'-nucleotidase, were determined in homogenates of rat embryos obtained on the 14th day of gestation and were found to be different than those reported for adult tissues. 2. Measurements of various organelle reference enzyme activities on the 14th and 15th days of gestation revealed a pattern of selective rates of subcellular organelle biogenesis during this period: lysosomes greater than mitochondria greater than endoplasmic reticulum = plasma membranes.
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PMID:Characterization and comparison of two plasma membrane reference enzymes with those of other organelles during mammalian embryogenesis. 624 3

The ability of nonionic detergents to solubilize the membrane-bound enzymes of the brush-border plasma membrane of Hymenolepis diminuta was investigated. Of the detergents tested (Triton X-100, Tween 80, Brij 35, Lubrol PX and WX, W-1, and beta-octyl-D-glucoside), only Triton was an effective solubilizing agent. Optimal solubilization was achieved by incubating an isolated fraction of the brush-border membrane in the presence of 1% Triton X-100 for 60 min at 37 C, followed by centrifugation at 100,000 g for 60 min at 25 C. This treatment resulted in solubilization of 94% of the alkaline phosphohydrolase, 91% of the phosphodiesterase and ribonuclease, and 88% of the 5'-nucleotidase activities. The pH optima for enzymes solubilized in nonionic and ionic detergents (Triton and sodium dodecyl sulfate, respectively) did not differ. Isoelectric focusing of the Triton-solubilized material demonstrated the presence of at least 14 polypeptides, a majority of which had isoelectric points below pH 7.
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PMID:Solubilization of the membrane-bound enzymes of the brush-border plasma membrane of Hymenolepis diminuta (Cestoda) using nonionic detergents. 628 6

We studied 5'-nucleotidase in preparations of synaptic plasma membranes from bovine caudate nucleus. The best substrates for this membrane-bound enzyme were purine nucleotides, particularly 5'AMP. Effects of metal cations and chelating agents suggest that 5'-nucleotidase is a metalloprotein. Optimal conditions for solubilization of the 5'-nucleotidase were found by using a low concentration of the zwitterionic detergent sulfobetaine 14. In contrast, another membrane-bound enzyme, acetylcholinesterase, was not solubilized under these conditions, but only in the presence of Triton X-100. The effects of lectins (concanavalin A, Lens culinaris agglutinin, wheat germ agglutinin, and Limulus polyphemus agglutinin) showed that both enzymes are glycoproteins. Sequential hydrolysis with specific glycosidases produced modifications of the effect of lectins on these enzymes. The results suggest the presence of a complex-type glycosylation, with a fucose residue on the internal N-acetyl-D-glucosamine of the pentasaccharide core.
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PMID:5'-Nucleotidase from bovine caudate nucleus synaptic plasma membranes: specificity for substrates and cations; study of the carbohydrate moiety by glycosidases. 632 59

After immunization with purified human placental ecto-5'-nucleotidase and fusion, 18 different hybrids were obtained which produce an antibody inhibitory for enzyme activity. These antibodies show complete cross-reactivity with the enzyme in a membrane-bound form or on the surface of intact cells. After cloning and ascites production, the antibody of one clone ( IFH - 5N1 ) was studied in greater detail. The IFH - 5N1 antibody is of the IgG 1 subclass. Optimal enzyme inhibition is 90% for purified 5'-nucleotidase and 80% for the enzyme on lymphoblasts. The specificity of this antibody is further demonstrated by enzyme inhibition assays and fluorescence labeling using various 5'-nucleotidase-positive and -negative human cells such as peripheral blood lymphocytes, leukemic cells, lymphoblastoid B- and T-cell-lines and fibroblasts. The antibody should provide a useful tool for the diagnosis of certain forms of acute leukemias and for the study of normal human lymphocyte subpopulations.
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PMID:Development and properties of a monoclonal antibody specific for human ecto-5'-nucleotidase. 632 7

Thiopurines are used for treatment of several diseases. Cytotoxicity is caused by the derived compounds 6-thioguanine nucleotides (TGNs) and methyl-6-thioinosine monophosphate (methylthio-IMP). The 6-thiopurine mononucleotides 6-thio-IMP (thio-IMP), 6-thio-GMP (thio-GMP) and methylthio-IMP can be catabolized by purine 5'-nucleotidase. It has been shown that the various 5'-nucleotidases are key enzymes for (6-thio)-purine metabolism. We aimed to investigate whether the overall 5'-nucleotidase (5'NT) activity is correlated with the efficacy and toxicity of 6-thiopurine nucleotides. Substrate affinity of 5'NT for IMP, GMP, AMP, thio-IMP, thio-GMP and methylthio-IMP was studied in human lymphocytes. For each of the substrates, the pH for optimal overall enzyme activity has been determined at a pH range between 6 and 10. At the optimal pH, assays were performed to establish Km and Vmax values. Optimal pH values for the various substrates were between 7 and 8.5. Km values ranged from 33 to 109 microM, Vmax ranged from 3.99 to 19.5 nmol/10(6) peripheral mononuclear cells (pMNC) h, and Vmax/Km ratios ranged from 105 to 250. The results did not show a distinct preference of 5'NT activity for any of the tested thiopurine nucleotides. The enzyme kinetic studies furthermore revealed substrate inhibition by thio-IMP and thio-GMP as a substrate. Inhibition by thio-GMP also seems to occur in patients treated with 6-mercaptopurine (6 MP); subsequently, this may lead to toxicity in these patients.
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PMID:Role of 5'-nucleotidase in thiopurine metabolism: enzyme kinetic profile and association with thio-GMP levels in patients with acute lymphoblastic leukemia during 6-mercaptopurine treatment. 1599 89