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)

1. Treatment of hamster heart cells in primary culture with 5-bromo-2'-deoxyuridine resulted in the greatly increased activity of a particulate Ca2+- or Mg2+-dependent ATPase (adenosine triphosphatase). 2. 5-Bromo-2'-deoxyuridine exerted these effects only when it was incorporated into cellular DNA, and then in a concentration-dependent manner. 3. Serially replated cells contained less of the activity (expressed as a function of total cell protein) than did the primary cultures, but the stimulation caused by 5-bromo-2'-deoxyuridine addition was much greater. 4. The affected enzyme was apparently localized in the plasma membrane of the cells with its active centre exposed to the outer environment [ecto-(ATPase) dependent on Ca2+ or Mg2+].5. The activity was unaffected by treatment with p-chloromercuriphenylsulphonate, ouabain andverapamil. 6. Ecto (5'-nucleotidase) activity was not increased by 5-bromo-2'-deoxyuridine treatment of cells, and ecto-(p-nitrophenyl phosphatase) activity was only slightly enhanced.
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PMID:5-bromo-2'-deoxyuridine-stimulated calcium ion- or magnesium ion-dependent ecto-(adenosine triphosphatase) activity of cultured hamster cardiac cells. 14 81

A procedure was developed for the isolation of cardiac sarcolemmal vesicles. These vesicles are enriched about ten-fold (with respect to the tissue homogenate) in K+-stimulated p-nitrophenylphosphatase, (Na+ + K+)-ATPase, 5'-nucleotidase activities and sialic acid content, all of which are believed to be components of the sarcolemma. The sarcolemma of tissue culture cardiac cells were radioiodinated and the distribution of this radioiodine paralleled the distribution of the other membrane markers above. There was very little contamination of the sarcolemmal fraction by sarcoplasmic reticulum (as judged by Ca2+-ATPase and glucose-6-phosphatase activities) or inner mitochondrial membranes (as judged by succinate dehydrogenase activity). There may, however, be some contamination by outer mitochondrial membranes (as judged by monoamine oxidase and rotenone-insensitive NADH cytochrome c reductase activities) which have rarely been monitored in cardiac sarcolemmal preparations. The purity of this preparation is good when compared with other cardiac sarcolemmal preparations. This preparation should be very useful in studying the roles of the cardiac sarcolemma (e.g. in excitation contraction coupling and Ca2+ binding).
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PMID:Isolation and characterization of cardiac sarcolemma. 22 23

By means of a preparation technique based on the discontinuous sucrose density gradient, subcellular fractions were isolated from guinea pig intestinal smooth muscle cells. A fraction which distributed to a 33% sucrose layer showed relatively high activities of 5'-nucleotidase, Na+ . K+-ATPase and ouabain sensitive Na+ . K+-ATPase. The fraction had a low NaN3 sensitive Mg2+-ATPase activity. On the other hand, the high activity of glucose-6-phosphatase showed a broad distribution. Though the sucrose density gradient proceeded over a series of the fine layers, cross-contamination of microsome into the 33% sucrose fraction was not reduced. To reduce microsomal cross-contamination, another procedure was employed. The homogenization time of 77000 xg sediment to be layered on the top of the sucrose density gradients was prolonged. This procedure did not change the distribution of K+ activated p-nitrophenylphosphatase, K+ activated ouabain sensitive p-nitrophenylphosphatase and ouabain sensitive Na+ . K+-ATPase activities. The peak of NADH cytochrome c reductase activity was shifted to a 38% sucrose fraction from a 33% sucrose fraction and the activity of this marker enzyme in the 33% sucrose fraction decreased to 60% of that of the prior procedure.
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PMID:[Examination of plasma membrane-enriched fraction from guinea pig intestinal smooth muscle by means of some marker enzymes (author's transl)]. 23 74

Whole sheets of plasma membrane, each with their attached flagellum, were purified from Trypanosoma brucei. The method devised for their isolation included a new technique of cell breakage that used a combination of osmotic stress followed by mechanical sheer and avoided the problem of extreme vesiculation as well as the trapping of organelles in cell 'ghosts'. The purified membranes all contained the pellicular microtubular array. The antigenic surface coat was completely released from the plasma membrane during the isolation procedure. The membranes had a very high cholesterol/phospholipid ratio (1.54). A large proportion (42%) of the cellular DNA was recovered in the plasma-membrane fraction unless a step involving deoxyribonuclease treatment, which decreased the DNA content to less than 13%, was included before secrose-density gradient centrifugation. This step also aided the separation of plasma membranes from other cellular components. The ouabain-sensitive Na+ + K+-stimulated adenosine triphosphatase and adenylate cyclase co-purified with the plasma membranes. Although 5'-nucleotidase was thought to be a plasma-membrane component, it was easily detached from the membrane. The purified membranes were essentially free of L-alanine-alpha-oxoglutarate aminotransferase, L-asparte-alpha-oxoglutarate aminotransferase, malate dehydrogenase, oligomycin-sensitive adenosine triphosphatase, glucose 6-phosphatase, Mg2+-stimulated p-nitrophenyl phosphatase and catalase.
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PMID:The isolation and partial characterization of the plasma membrane from Trypanosoma brucei. 48 94

Rat serum 5'-nucleotidase, L-leucyl-beta-naphthylamidase and beta-glycerophosphatase activities are increased whilst alkaline p-nitrophenylphosphatase and alkaline phosphodiesterase activities are unchanged or decreased three days after bile duct ligation. Affinity chromatography on an immobilised antiserum raised against highly purified liver plasma membranes showed that although 5'-nucleotidase in normal serum is unrelated to the 5'-nucleotidase of liver plasma membrane, the 5'-nucleotidase of bile and much of the 5'-nucleotidase in the jaundiced serum are closely related to the plasma membrane enzyme. Since bile is rich in 5'-nucleotidase, the changes in level of this enzyme after bile duct ligation are most simply explained by leakage of bile into the blood; changes in the patterns of the other enzymes are shown to be consistent with this explanation. The jaundiced serum was examined by gel exclusion chromatography and flotation in sucrose gradients for the presence of small fragments of plasma membrane as reported in human jaundiced sera, but no such fragments could be detected three days after bile-duct ligation.
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PMID:Bile 5'-nucleotidase in the serum of jaundiced rats. 89 Sep 46

A subcellular fractionation method to isolate simultaneously apical and basolateral plasma membrane fractions from the human adenocarcinoma cell line Caco-2, grown on filter supports, is described. The method employs sucrose-density-gradient centrifugation and differential precipitation. The apical membrane fraction was enriched 14-fold in sucrase-isomaltase and 21-fold in 5'-nucleotidase compared with the homogenate. The basolateral membrane fraction was enriched 20-fold relative to the homogenate in K(+)-stimulated p-nitrophenylphosphatase. Alkaline phosphatase was enriched 15-fold in the apical membrane fraction and 3-fold in the basolateral membrane fraction. Analytical density-gradient centrifugation showed that this enzyme was a true constituent of both fractions, and experiments measuring alkaline phosphatase release following treatment with phosphatidylinositol-specific phospholipase C showed that in both membrane fractions the enzyme was glycosyl-phosphatidylinositol-linked. There was very little contamination of either membrane fraction by marker enzymes of the Golgi complex, mitochondria or lysosomes. Both membrane fractions were greater than 10-fold purified with respect to the endoplasmic reticulum marker enzyme alpha-glucosidase. Protein composition analysis of purified plasma membrane fractions together with domain-specific cell surface biotinylation experiments revealed the presence of both common and unique integral membrane proteins in each plasma membrane domain. The post-synthetic transport of endogenous integral plasma membrane proteins was examined using the devised subcellular fractionation procedure in conjunction with pulse-chase labelling experiments and immunoprecipitation. Five common integral membrane proteins immunoprecipitated by an antiserum raised against a detergent extract of the apical plasma membrane fraction were delivered with the same time course to each cell-surface domain.
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PMID:The post-synthetic sorting of endogenous membrane proteins examined by the simultaneous purification of apical and basolateral plasma membrane fractions from Caco-2 cells. 131 18

Thirty-three different flavonoids were screened for their ability to influence ATP-dependent Ca2+ uptake by rat liver plasma membrane vesicles. Nine of the flavonoids, at a concentration of 100 microM inhibited Ca2+ uptake by more than 20%. The remaining 24 flavonoids exhibited little or no effect. The relative order of potency of the more biologically active flavonoids was myricetin greater than butein greater than phloretin = luteolin greater than eriodictyol = silybin. Myricitrin and phloridzin, the glycosides of myricetin and phloretin, respectively, had no effect. The degree of inhibition caused by myricetin was concentration dependent and was also affected by the preincubation time. After 10 min of preincubation, 52 microM myricetin lowered the initial rate of 45Ca uptake by 50%. The inhibition by myricetin was non-competitive with respect to Mg-ATP and of a mixed type with respect to Ca2+. At a concentration of 100 microM, myricetin had no effect on several plasma membrane enzymes such as 5'-nucleotidase, alkaline phosphatase and a Ca2(+)-activated ATPase but inhibited K(+)-dependent p-nitrophenyl phosphatase by 83%. The ATP-dependent Ca2+ transport systems located on the plasma membrane or endoplasmic reticulum derived from other tissues were also inhibited by myricetin. Analysis of the structure-activity relationship revealed that lipid solubility and polyhydroxylation particularly at positions 5,7,3' and 4' of the flavonoid ring structure enhanced the ability of the flavonoid to inhibit Ca2+ uptake. The results suggest that inhibition of Ca2+ transport activity probably involves the interaction of the phenolic groups of the flavonoid with the Ca2+ transporting protein.
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PMID:Effect of myricetin and other flavonoids on the liver plasma membrane Ca2+ pump. Kinetics and structure-function relationships. 199 24

The vasodilating action of nitroglycerin (NTG) is thought to be mediated by its metabolic activation to nitric oxide (NO) in the vascular smooth muscle cell, but the site at which this process occurs has not been defined. To determine which cellular component is primarily responsible for this metabolic activation, subcellular fractions of bovine vascular smooth muscle cells were prepared and incubated with NTG along with cofactors. Time-dependent headspace NO concentrations generated in these preparations were determined directly by chemiluminescence detection. A mathematical model was developed to relate headspace NO with the NO-generating activity in each incubation, correcting for the concurrent processes of NO partitioning between the headspace and the incubation medium, and NO degradation in these two phases. The estimated NO-generating activities from different subcellular fractions were well correlated with the activities of two enzyme markers of the plasma membrane (K(+)-activated ouabain sensitive p-nitrophenyl phosphatase and 5'-nucleotidase), but not with those of the mitochondria, endoplasmic reticulum or the cytosol. These results indicate that the enzyme(s) responsible for the metabolic activation of NTG, and possibly other organic nitrate vasodilators, are associated with the plasma membrane in bovine coronary smooth muscle cells.
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PMID:Identification of the subcellular site for nitroglycerin metabolism to nitric oxide in bovine coronary smooth muscle cells. 211 Sep 75

A (H+ + K+)-ATPase-enriched membrane fraction derived from the fundic portion of hog gastric mucosa was obtained by a combination of differential and repeated 7% Ficoll gradient centrifugation. The microsomal membrane fraction isolated by repeated 7% Ficoll gradient centrifugation was free of ouabain-sensitive (Na+ + K+)-ATPase, 5'-nucleotidase and succinate dehydrogenase; and it was highly enriched in (H+ + K+)-ATPase and K(+)-stimulated p-nitrophenylphosphatase (p-NPPase). The (H+ + K+)-ATPase had a pH optimum of 7.4 and was stimulated by Tl+, K+, Rb+ and NH4+ with Ka values of 0.0667, 0.526, 0.667 and 3.03 mM, respectively, at this pH. On the other hand, monovalent cations such as Na+, Li+ and (CH3)4N+ as well as divalent cations such as Cu2+, Ca2+, Ba2+, Sr2+ and Cd2+ inhibited this enzyme activity concentration-dependently. Ouabain and oligomycin had no effect, whereas omeprazole, a specific (H+ + K+)-ATPase inhibitor, inhibited this enzyme activity in a pH-dependent manner. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis showed a major band (greater than or equal to 90% of protein) at 97,400 daltons, which was phosphorylated in the presence of Mg2+ and [gamma-32P]-ATP and dephosphorylated in the presence of K+. The present method was very simple, and the (H+ + K+)-ATPase activity of the microsomal fraction obtained by this method was much higher compared with those obtained by other methods such as free-flow electrophoresis.
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PMID:Purification and characterization of (H+ + K+)-ATPase from hog gastric mucosa. 215 97

Cardiac contractile function is dependent on the integrity and function of the sarcolemmal membrane. Swimming exercise training is known to increase cardiac contractile performance. The purpose of the present study was to examine whether a swimming exercise program would alter sarcolemmal enzyme activity, ion flux, and composition in rat hearts. After approximately 11 wk of exercise training, cardiac myosin and actomyosin Ca2+-adenosinetriphosphatase (ATPase) activity was significantly higher in exercised rat hearts than in sedentary control rat hearts. Glycogen content was increased in plantaris and gastrocnemius muscles from exercised animals as was succinic dehydrogenase activity in gastrocnemius muscle of exercised rats in comparison to sedentary rat preparations. Sarcolemmal vesicles were isolated from hearts of exercise-trained and control rats. Sarcolemmal Na+-K+-ATPase and K+-p-nitrophenylphosphatase activities, Na+-Ca2+ exchange, and passive Ca2+ binding did not differ between the two groups. ATP-dependent Ca2+ uptake and 5'-nucleotidase activity were elevated in the cardiac sarcolemmal vesicles isolated from exercised animals compared with sedentary control rats. Sarcolemmal phospholipid composition was not altered by the exercise training. Our results demonstrate that swimming training in rats does not affect most parameters of cardiac sarcolemmal function or composition. However, the elevated sarcolemmal Ca2+ pump activity in exercised rats may help to reduce intracellular Ca2+ and augment cardiac relaxation rates. The enhanced 5'-nucleotidase activity may stimulate adenosine production, which could affect myocardial blood flow. The present results further our knowledge on the subcellular response of the heart to swimming training in the rat.
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PMID:Effects of chronic swimming training on cardiac sarcolemmal function and composition. 273 62


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