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)

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
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PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.
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PMID:Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved. 18 60

(1) The histochemical staining pattern of succinic dehydrogenase (SDH) does not show unequivocal differentiation between the type I red and type II red fibres in mammalian striated muscles. (2) Since high biochemical activity of beta-hydroxybutyric dehydrogenase (beta-HOBDH) occurs in mitochondria of the type I red fibres, the histochemical localization of this enzyme may show a pattern of staining reciprocal to that seen for myofibrillar ATPase. (3) It remains to be confirmed that the type I red fibres, which are possibly slow-twitch physiologically, possess the highest concentration of myoglobin. The histochemical correlation of myoglobin and myofibrillar ATPase in serial sections should be studied. (4) In order to achieve a more realistic picture, various glycolytic and glycogenolytic enzymes should be incubated according to the gelatin film technique, or semipermeable membrane technique or collagen polypeptide technique. A histochemical correlation of phosphorylase, LDH, PFK, alpha-glycerophosphate dehydrogenase, and myofibrillar ATPase in adjacent muscle sections may throw light on the histochemical characteristics of the different fibre-types. (5) The specific histochemical demonstration of AMPase is achieved following preincubation of tissue sections. (6) ADPase has been demonstrated by the calcium precipitation technique only (GUTH and YELLIN, 1971). A number of studies claim, however, that ADPase is not demonstrable histochemically in muscle fibres. (7) The presence of magnesium ions is a prerequisite for the adequate histochemical demonstration of mitochondrial ATPase. The latter is inhibited almost completely by 40 mM Ca++ (when Mg++ is not added) at both neutral and alkaline pH values. (8) The histochemical activity of SR-AT-Pase seen as continuous reticula but without punctuate and sub-sarcolemmal staining possibly represents the extra ATPase of SR. (9) On the basis of myofibrillar ATPase reaction, an inherent heterogeneity, between the type II red and type II white may be recognized. In addition, the above fibre-types possess their respective sub-populations. (10) Following diK+ EDTA preincubation, some type II red fibres show selective lability. These are the mitochondria-rich fibres. Thus in the total absence of both punctuate and subsarcolemmal staining, the presence of mitochondrial ATPase activity under the histochemical conditions for myofibrillar ATPase is unlikely. (11) The reaction pattern of CK/ATPase (coupled reaction) at pH 6.9 is distinctly intermyofibrillar and unlike SDH-pattern. This reticular reaction is associated mainly with the SR and hence the importance of transphosphorylation in this organelle for the Ca++ uptake and muscle relaxation. (12) The CK/ATPase reaction at pH8.0 has shown important histoenzymatic characteristics. At this pH value the type I red fibres and slow-twitch soleus show myofibrillar reaction pattern. This identical histochemical behaviour suggests that type I red fibres are possibly slow-contracting...
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PMID:Histochemical characteristics of vertebrate striated muscle: a review. 18 61

It was found that mitochondria from human placenta exhibited an ADPase activity with the following characteristics. The enzyme responsible for this activity was associated with the inner mitochondrial membrane. It was not released by treatment of the submitochondrial particles with solutions of high ionic strength. Maximal ADP hydrolysis was reached at pH 8. Specific inhibitors for alkaline phosphatase (L-phenylalanine), myokinase (P1,P5-di(adenosine-5')pentaphosphate), or 5'-nucleotidase (concanavalin A) did not decrease ADP hydrolysis. ATP synthesis from ADP by myokinase was about 13 nmol/mg/min, whereas ADP hydrolysis reached values around 500 to 550 nmol/mg/min, indicating that a myokinase-H+ATPase combination could not account for the observed rates of ADP hydrolysis. The activity was stimulated by Mg2+, but high concentrations of this cation produced inhibition. High ADP concentrations did not inhibit ADPase activity. Kinetic measurements of the activity in the submitochondrial particles showed that the true substrate was ADP-Mg. The kinetic studies showed V(app) values of 476 and 270 nmol/mg/min, and Kmapp values of 416 and 8.7 microM.
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PMID:Subcellular localization and properties of adenosine diphosphatase in human placenta. 147 Jun 6

The granular ATP released from chromaffin cells during the secretory response can be hydrolyzed by ectonucleotidases that are present in the plasma membrane of these cells. The ecto-ATPase activity showed a Km for ATP of 250 +/- 18 microM and a VMAX value of 167 +/- 25 nmol/10(6) cells x min (1.67 mumol/mg protein x min) for cultured chromaffin cells, while the ecto-ADPase activity showed a Km value for ADP of 375 +/- 40 microM and a VMAX of 125 +/- 20 nmol/10(6) cells x min (1.25 mumol/mg protein x min). The ecto 5'-nucleotidase activity of cultured chromaffin cells was more specific for the purine nucleotides, AMP and IMP, than for the pirimidine nucleotides, CMP and TMP. The Km for AMP was 55 +/- 5 microM and the VMAX value was 4.3 +/- 0.8 nmol/10(6) cells x min (43 nmol/mg protein x min). The nonhydrolyzable analogs of ADP and ATP, alpha, beta-methylene-adenosine 5'-diphosphate and adenylyl-(beta, gamma-methylene)-diphosphonate were good inhibitors of ecto 5'-nucleotidase activity, the KI values being 73.3 +/- 3.5 nM and 193 +/- 29 nM, respectively. The phosphatidylinositol-specific phospholipase C released the ecto-5'-nucleotidase from the chromaffin cells in culture, thus suggesting an anchorage through phosphatidylinositol to plasma membranes. The presence of ectonucleotidases in chromaffin cells may permit the recycling of the extracellular ATP exocytotically released from these neural cells.
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PMID:Presence of ectonucleotidases in cultured chromaffin cells: hydrolysis of extracellular adenine nucleotides. 215 57

Biologically active concentrations of potently vasoactive and platelet-active adenine nucleotides are generated in plasma by a variety of pathophysiological mechanisms. Although there is evidence that ATP and ADP are inactivated by endothelial ectonucleotidases, there has been little attempt to study the metabolic routes of their catabolism in blood or to assess the contribution of this process to their clearance in vivo. Therefore, we have studied the rates and patterns of catabolism of ATP, ADP, and AMP in whole blood, plasma, and isolated blood cells. Rates of degradation of each nucleotide in cell-free plasma ranged from 0.07-0.32 nmol/min/ml with 1 microM substrates to 1.1-3.6 nmol/min/ml with 100 microM substrates. The pattern of catabolism indicated that sequential dephosphorylation from ATP----ADP----AMP----adenosine occurs. In whole blood, the pattern was similar although ATP and ADP (but not AMP) breakdown was more rapid. This was due to leukocyte ectonucleotidase activity. The use of selective inhibitors demonstrated that catabolism was not due to nonspecific phosphatase activity and that plasma 5'-nucleotidase is distinct from ATPase or ADPase. In leukocytes, ATPase and ADPase activities were distinguishable, and each contributed substantially to the rates of catabolism in whole blood. Leukocyte 5'-nucleotidase did not measurably contribute to AMP dephosphorylation in blood. By comparison, ecto-ATPase and ecto-ADPase activities on cultured human umbilical vein endothelial cells were similar to those on leukocytes while endothelial 5'-nucleotidase per 10(6) cells was equivalent to the soluble activity in 1 ml of blood or plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolism of adenine nucleotides in human blood. 254 57

Cultivated endothelial cells of calf aorta (line BKEz-7) possess an effective ectophosphatase system (enzyme activities: ATPase 38.0 +/- 10.2; ADPase 9.2 +/- 4.2; 5'-nucleotidase 4.1 +/- 2.6 fmol/cell.min). Drugs with central depressive activity such as promazine, chlorpromazine, and meprobamate inhibit the activity of the ecto-ATPase. A possible connection between the inhibitory activity on the ecto-ATPase and their central depressive effects is discussed.
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PMID:[The ectophosphatase activity of cultured endothelial cells of calf aorta and the effect of drugs on ecto-ATPase]. 255 7

Mature secretory granules in paraneurons contain ATP amongst other small messenger molecules. In the islet organ such stores of adenine nucleotides readily can be demonstrated by means of the quinacrine fluorescence method. ATP is co-released together with other granule constituents when the major hormones are exocytosed. The distribution of ATP splitting enzymic activities was studied in the pancreas of the mouse and rat, in order to obtain information on the possible fate of this small messenger molecule. ATPase, ADPase, and AMPase (5'-nucleotidase) were demonstrated with lead precipitation methods, L-tetramisole was used to inhibit unspecific alkaline phosphatase (alPase); alPase activities were shown with tetrazolium methods, using 5-bromo-4-chloro-3-indoxyl phosphate as substrate. Most endothelial cells of the vascular bed, both in the exocrine and in the endocrine pancreas, are reactive for ATPase, ADPase, AMPase and alPase. Smooth muscle cells are strongly reactive for ATPase and AMPase, vascular adventitial fibroblasts (veil cells) stain for ATPase and alPase, as do some lamellar cells at the islets surface. Staining for ADPase serves as a selective method to demonstrate the vascular bed. Comparable results are obtained with the alPase reaction, though insular non-B-cells are also reactive. ATPase staining is less useful for demonstrating vascular connections because moderate reactivity of exocrine parenchyma and adventitial tissue obscures the picture. AMPase activity is strong in the venous segments of the capillary net and in collecting veins but the reaction obviously does not demonstrate significant portions of the residual capillary network. Weak AMPase activity is seen in the insular parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fate of ATP in secretory granules: phosphohydrolase studies in pancreatic vascular bed. 255 47

We have previously assigned human ecto-5'-nucleotidase (NT) to chromosome 6 on the basis of conversion of exogenously supplied [14C]AMP to adenosine by whole cells of human and Chinese hamster hybrids carrying chromosome 6. In this paper we demonstrate that the activity on human MRC-5 fibroblasts is typical of previously described and purified ecto-5'-nucleotidases. In contrast to MRC-5 cells, Chinese hamster V79A2 cells weakly express an AMPase activity that is not NT. The cytosolic form of NT in human and hybrid fibroblasts is similar to the ectoenzyme in substrate specificity. Hybrids that lack chromosome 6 express neither the ecto- nor the cytosolic enzyme, suggesting that both forms may be coded by the same gene on chromosome 6. Ecto-ATPase, ecto-ADPase, and ecto-ADP kinase activities are each expressed at similar levels in MRC-5 and V79A2. The ATPase, ADPase and NT activities of MRC-5 cells act sequentially to generate adenosine. A similar cascade acts on V79A2 cells but the lack of NT causes the accumulation of AMP.
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PMID:Nucleotide ectoenzyme activities of human and Chinese hamster fibroblasts in tissue culture. 256 Jun 29

The extracellular reaction sequence ATP----ADP----AMP----adenosine participates in regulating the time course of cellular response during crisis or signaling events, such as thrombus formation or neurotransmission. We have investigated the whole time course of hydrolysis of ATP to adenosine by recirculating adenine nucleotide substrates over smooth muscle cells attached to polystyrene beads. Kinetic parameters were estimated for each reaction by fitting observed time courses to models of the pathway. In spite of the inhibition of 5'-nucleotidase by ADP, adenosine was produced very rapidly by smooth muscle cells. Comparisons of the apparent Km values of ADPase and 5'-nucleotidase (determined from experiments in which each substrate was used as the initial substrate with Km values observed when each substrate was supplied from the upstream reaction) suggest that the local concentrations of substrate supplied from the preceding reactions are very much higher than those in the bulk phase. This enhancement of efficiency overcomes the effect of the feed-forward inhibition to give rise to very rapid adenosine production from ADP or ATP. These observations are in marked contrast to our previous findings with endothelial cells (Gordon, E. L., Pearson, J. D., and Slakey, L. L. (1986) J. Biol. Chem. 261, 15496-15504), on which feed-forward inhibition causes a profound lag in adenosine production from adenine nucleotides and on which there are no apparent surface effects on substrate delivery.
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PMID:The hydrolysis of extracellular adenine nucleotides by arterial smooth muscle cells. Regulation of adenosine production at the cell surface. 280 4


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