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)

The specificity of lactoperoxidase-catalyzed iodination for the proteins of the hepatoma tissue culture cell plasma membrane was examined by histochemical, biochemical, and cell fractionation techniques. Light microscope autoradiography of sectioned cells shows the incorporated label to be localized primarily at the periphery of the cell. Most of this label can be released from the cell by trypsin but not by collagenase or hyaluronidase. The label is recovered from the cells as either monoiodotyrosine or diiodotyrosine after hydrolysis of cell extracts with a mixture of proteolytic enzymes. The label co-purifies during cell fractionation with an authentic liver cell plasma membrane marker enzyme, 5'-nucleotidase. Thus, the incorporated iodide is itself a valid marker for those membrane polypeptides having tyrosine residues accessible to the lactoperoxidase. The polypeptide complexity of the purified plasma membrane was examined by high resolution dodecyl sulfate-polyacrylamide gel electrophoresis. At least 50 polypeptides in the membrane are accessible to iodination. These polypeptides probably represent the bulk of the protein mass of the membrane and iodinating them does not affect cell viability, growth rate, or cell function. Labeling experiments with fucose and glucosamine show that at least nine of the iodinated peptides may be glycoproteins.
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PMID:Proteins of the hepatoma tissue culture cell plasma membrane. 0 57

The influence of the mode of preparation upon some of the characteristics of white adipose tissue plasma membranes and microsomes has been reported. Plasma membrane fractions prepared from mitochondrial pellet were shown to have higher specific activities of (Mg2+ + Na+ + K+)-ATPase than plasma membranes originating in crude microsomes. Isolation of fat cells by collagenase treatment was found to result in a decrease in specific activity of the plasma membrane enzymes; in plasma membranes prepared from isolated fat cells, the specific activity values obtained for (Mg2+ + Na+ +k+)-ATPase and 5'-nucleotidase were only 42% and 6.3% respectively of those obtained in plasma membranes prepared from whole adipose tissue. Purification of whole adipose tissue crude microsomes by hypotonic treatment caused extensive solubilization of the endoplasmic reticulum marker enzymes, NADH oxidase and NADPH cytochrome c reductase. The lability of endoplasmic reticulum marker enzymes, however, was found to be greatly diminished in the preparations from isolated fat cells. The possibility that NADH oxidase and NADPH cytochrome c reductase activities found in the plasma membranes are microsomal enzymes adsorbed by the plasma membranes is discussed. The peptide patterns as well as the NADH oxidase and NADPH cytochrome c reductase activity patterns of plasma membranes and purified microsomes were compared by means of sodium dodecyl sulfate or Triton X-100 polyacrylamide gel electrophoresis.
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PMID:Comparison of plasma membranes and endoplasmic reticulum fractions obtained from whole white adipose tissue and isolated adipocytes. 12 89

A method is described for isolation of plasmatic membranes of rat fatty cells immediately from fatty tissue without the treatment with collagenase. Homogenization of fatty tissue was carried out in large volumes of buffered sucrose and EDTA at room temperature followed by sucrose density gradient centrifugation. The preparations obtained exhibited high specific activity of the marker enzyme of plasmatic membranes [5'-nucleotidase and K+, Na+-ATPase], as well as high ability for specific binding of insulin.
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PMID:[Isolation of the plasma membranes of fat cells without using collagenase]. 22 73

Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split Pi from 5'-AMP at a rate of 87 nmol/h per microgram DNA, and from beta-glycerophosphate at a rate of 25 nmol/h per microgram DNA. Km for 5'-AMP was about 54 microM. Adenosine or theophylline inhibited the 5'-AMP hydrolysis. Homogenization of the cells increased the activity toward 5'-AMP by 23% and that toward beta-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5'-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5'-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5'-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5'-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5'-AMP in cortisone-treated rats.
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PMID:5'-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats. 38 76

When liver cells were dispersed with collagenase, their 5'-nucleotidase activity decreased to half the initial level, but it increased to the original level again on culture of the cells for a few days. The activity of another membrane enzyme, alkaline phosphatase, did not decrease on dispersion of the cells, but it increased about 10-fold on culture of the cells. These inductions did not require any hormone, but the effects were greater at a high cell density. These enzymes are located in both the plasma membranes and the cytoplasm, but the enzymes in these two locations can be distinguished by differences in their pH optima, substrate specificities, and susceptibilities to inhibitors. The increases were found to be due to increases in the activity of only the enzymes in the plasma membranes. The increases in enzyme activities were inhibited by actinomycin D, cycloheximide, and puromycin. The activities of leucine aminopeptidase and aminopeptidase B, other membrane enzymes, remained constant during dispersion and culture of the cells. These results show that enzymes in the cell membranes are affected in different ways by cell dispersion with collagenase and subsequent culture of the cells.
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PMID:Biochemical studies on liver functions in primary cultured hepatocytes of adult rats. III. Changes of enzyme activities on cell membranes during culture. 52 39

1. Rat livers were dissociated into their constituent cells by perfusion through the portal vein with a medium containing collagenase, and hepatocytes separated from non-parenchymal cells. 2. It is shown that the procedure described by Wisher & Evans [(1975) Biochem. J. 146, 375-388] for preparation of plasma membranes from liver tissue when applied to isolated hepatocytes also yielded subfractions of similar morphology and marker-enzyme distribution. 3. Thus the distribution of alkaline phosphodiesterase, 5'-nucleotidase and the basal and glucagon-stimulated adenylate cyclase among two 'light' vesicular and one 'heavy' junction-containing plasma-membrane subfractions paralleled that reported for tissue-derived plasma-membrane subfractions. 4. Increased recoveries and specific activities of plasma-membrane marker enzymes were obtained when soya-bean trypsin inhibitor was included in the collagenase-containing perfusion media used to dissociate the liver. 5. Polyacrylamide-gel-electrophoretic analysis of the corresponding plasma-membrane subfractions prepared from liver tissue and isolated hepatocytes were generally similar. 6. The results indicate that the functional polarity of the hepatocyte's plasma membrane is retained after tissue dissociation. The damage occurring to plasma-membrane ectoenzymes by the collagenase-perfusion procedure is discussed.
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PMID:Preparation of plasma-membrane subfractions from isolated rat hepatocytes. 88 Feb 46

Two murine peritoneal macrophage cell lines have been isolated by transforming primary cells with simian virus 40 (SV40) origin-deleted DNA. These lines have been maintained in continuous culture for over 8 months and have been shown to express macrophage-specific properties throughout this time. The cell lines are F4/80 positive; express Fc receptors; will phagocytose immunoglobulin-coated red cells and latex beads; stain with neutral red; and have non-specific esterase and plasminogen activator activities. Lysozyme, collagenase, prostaglandin E2, acid phosphatase and 5'-nucleotidase activities have also been detected and quantified.
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PMID:Establishment of immortalized cell lines from mouse peritoneal macrophages following transformation with SV40 early region DNA deleted at the origin of replication. 185 Nov 33

A rapid procedure has been described for preparation of a relatively pure fraction of plasmatic membranes from adipose tissue without treatment with collagenase. Gentle homogenization of rat fatty tissue in a buffered sucrose solution yielded membrane fractions that could be separated from the bulk of contaminating mitochondria and microsomes by a series of differential and isopycnic centrifugations. The preparation obtained was enriched 12-fold with 5'-nucleotidase as compared with the initial homogenate and contained minimal contaminations with mitochondria or elements of endoplasmic reticulum.
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PMID:[A method of isolating plasma membranes from adipose tissue of rats without preliminary treatment with collagenase]. 283 29

These experiments were designed to determine whether hypercholesterolemia and the accumulation of cholesterol or cholesteryl esters in rabbit carrageenan granuloma macrophages might influence selected markers of macrophage activation. Granulomas induced by subcutaneous injection of carrageenan into rabbits were harvested after 4, 14, and 28 days. Macrophages were isolated from granuloma tissues by collagenase digestion and cultured overnight. Secretion of lysosomal beta-glucuronidase, membrane 5'-nucleotidase, cellular plasminogen activator, and superoxide anion generation were measured as markers of activation. beta-Glucuronidase activity secreted into the media by granuloma macrophages from normocholesterolemic (NC) and hypercholesterolemic (HC) rabbits showed a trend toward an increase with time between 4 and 14 days in both groups. This was confirmed in a separate experiment with a significant increase by 14 days, together with a significantly greater secretion by NC macrophages and a significantly elevated level of cellular beta-glucuronidase activity in NC relative to HC macrophages. Activity of the membrane ectoenzyme 5'-nucleotidase was minimal in lysates of NC or HC macrophages, in contrast to freshly isolated human monocytes, indicating that both NC and HC granuloma macrophages were highly activated. Cellular plasminogen activator activity was significantly increased between 4 and 14 days, and was significantly greater in HC than in NC macrophages at 14 days. Stimulation of macrophages with phorbol myristate acetate increased superoxide anion generation by both NC and HC macrophages; however, no difference in superoxide anion generation was observed between macrophages from NC and HC rabbits. On the basis of the 5'-nucleotidase findings, it is concluded that both the NC and HC granuloma macrophages are highly activated, and further that hypercholesterolemia does not enhance macrophage generation of superoxide anion, either spontaneously or as the result of phorbol myristate acetate stimulation. Although hypercholesterolemia results in macrophage activation in terms of an increased cellular plasminogen activator activity, the secretion of the lysosomal enzyme beta-glucuronidase is diminished. Thus, hypercholesterolemia associated with macrophage cholesterol and cholesteryl ester accumulation has no consistent overall influence on activation, a finding of potential importance in the context of atherogenesis.
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PMID:Influence of hypercholesterolemia and cholesterol accumulation on rabbit carrageenan granuloma macrophage activation. 283 4

On treatment with collagenase, brain microvessels, together with several protein components, lose some enzymatic activities such as alkaline phosphatase and gamma-glutamyltranspeptidase, whereas no change occurs in the activities of 5'-nucleotidase and glutamine synthetase. The energy-requiring "A-system" of polar neutral amino acid transport is also severely inactivated, whereas the L-system for the facilitated exchange of branched chain and aromatic amino acids is preserved. In the collagenase-digested microvessels, this leads to loss of the transtimulation effect of glutamine on the transport of large neutral amino acids, because such transtimulation is due to a cooperation between the A- and L-systems. By contrast, NH4+ maintains (and even enhances) its ability to stimulate the L-system of amino acid transport, presumably through glutamine synthesis within the endothelial cells.
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PMID:Isolated brain microvessels as in vitro equivalents of the blood-brain barrier: selective removal by collagenase of the A-system of neutral amino acid transport. 289 Jul 11


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