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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Miconazole at 10 mg/l effected rapid (less than 1 min) and substantial (greater than 99%) reductions of intracellular ATP concentrations in buffered suspensions of Candida albicans. This ATP-suppressive effect was mirrored by a rapid reduction in the viable counts of the suspensions. However, the presence of exogenous glucose or fructose (but not several other carbon sources) greatly retarded the ATP-suppressive effect of miconazole. Glucose and fructose could even reverse the suppression when they were added to miconazole-pretreated suspensions. These data indicated that the non-viable cells remained metabolically active. The abrogatory effect of glucose on ATP reduction was optimal between pH 6.5 and 7: it was prevented by fluoride, a known inhibitor of glycolysis, and 2-deoxy-D-glucose could not substitute for glucose, demonstrating that metabolism of glucose was essential for the effect. Two detergents and orthovanadate were much less potent ATP suppressors than miconazole, but the proton pump uncoupler, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) was 10 times more active. The results suggest that miconazole may reduce ATP either by uncoupling substrate uptake mechanisms dependent on the fungal membrane proton pump or by inhibition of plasma membrane ATPase.
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PMID:Abrogation by glucose of the ATP suppression induced by miconazole in Candida albicans. 253 95

The effect of vitamin A deficiency on the intestinal absorption of nutrients and the activities of brush border enzymes were studied in albino rats. Intestinal uptakes of D-glucose, L-methionine, L-tryptophan and L-histidine were significantly greater in vitamin A-deficient animals than in controls. The specific activities of total adenosine triphosphatase (ATPase), ouabain-sensitive ATPase, maltase and sucrase in the intestinal mucosa of vitamin A-deprived rats were 121, 124, 131 and 134 per cent respectively, of the corresponding values in control animals. The DNA content of the small intestine in vitamin A-deficient rats was 36.5 per cent lower than in control rats. The stimulation in digestive and absorptive capacity appears to be an adaptive change in vitamin A-deficiency which decreases the intestinal cell population.
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PMID:Effect of vitamin A deficiency on rat intestinal digestive & absorptive functions. 253 19

MgATPase activity of plasma membrane from sunflower roots purified by phase partitioning was tested using different permeabilizing agents. MgATPase activity showed similar dependence on Triton X-100, digitonin and Zwittergent 3-14 concentration, the curves resulted from the stimulatory and inhibitory reactions. The latency calculated at their optima was only 52%. In case of n-octyl glucoside the latency was 77%, while the highest latency (82%) was measured in the presence of lysophosphatidylcholine, and it was the only surfactant which did not inhibit the PM ATPase even at 10 times the concentration giving maximum release of latent activity. Therefore, for the further characterization of the PM ATPase lysophosphatidylcholine is suggested to be used as detergent.
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PMID:The effects of detergents on the ATPase activity of plasma membrane prepared by phase partitioning from sunflower roots. 253 29

In the presence of inhibitors for mitochondrial H+-ATPase, (Na+ + K+)- and Ca2+-ATPases, and alkaline phosphatase, sealed brush-border membrane vesicles hydrolyse externally added ATP demonstrating the existence of ATPases at the outside of the membrane ("ecto-ATPases"). These ATPases accept several nucleotides, are stimulated by Ca2+ and Mg2+, and are inhibited by N.N'-dicyclohexylcarbodiimide (DCCD), but not by N-ethylmaleimide (NEM). They occur in both brush-border and basolateral membranes. Opening of brush-border membrane vesicles with Triton X-100 exposes ATPases located at the inside (cytosolic side) of the membrane. These detergent-exposed ATPases prefer ATP, are activated by Mg2+ and Mn2+, but not by Ca2+, and are inhibited by DCCD as well as by NEM. They are present in brush-border, but not in basolateral membranes. As measured by an intravesicularly trapped pH indicator. ATP-loaded brush-border membrane vesicles extrude protons by a DCCD- and NEM-sensitive pump. ATP-driven H+ secretion is electrogenic and requires either exit of a permeant anion (Cl-) or entry of a cation, e.g., Na+ via electrogenic Na+/D-glucose and Na+/L-phenylalanine uptake. In the presence of Na+, ATP-driven H+ efflux is stimulated by blocking the Na+/H+ exchanger with amiloride. These data prove the coexistence of Na+-coupled substrate transporters, Na+/H+ exchanger, and an ATP-driven H+ pump in brush-border membrane vesicles. Similar location and inhibitor sensitivity reveal the identity of ATP-driven H+ pumps with (a part of) the DCCD- and NEM- sensitive ATPases at the cytosolic side of the brush-border membrane.
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PMID:Relation of ATPases in rat renal brush-border membranes to ATP-driven H+ secretion. 253

Limited tryptic digestion of fluorescein isothiocyanate (FITC)-labeled (H+-K+)-ATPase from rat resting light gastric membranes produced a soluble 27-kDa polypeptide which retained the fluorescence of the parent enzyme. Its production was markedly enhanced in the presence of an amphiphilic detergent, Zwittergent 3-14, which potently inhibits the ATPase activity. This increase is probably due to protection of certain tryptic cleavage sites through conformational changes of the membrane enzyme by the detergent. The NH2-terminal sequence of the 27-kDa polypeptide corresponded exactly to that beginning at Asn-369 of the cDNA-deduced primary structure of the rat ATPase. The presence of the phosphorylation site, Asp-385, and FITC-labeled Lys-517, which is known to be a part of the ATP-binding site, indicates that the 27-kDa polypeptide contains a major cytoplasmic portion of (H+-K+)-ATPase. Interestingly, the polypeptide was stained with periodate-Schiff's base, indicating its glycoprotein nature. The carbohydrate group attached to the polypeptide seems to include at least an N-linked high-mannose moiety, since the polypeptide showed Con A binding activity as detected with a Con A-biotin/avidin-peroxidase assay on nitrocellulose transblots. Also, its Con A binding activity was inhibited by excess methyl alpha-D-mannopyranoside and disappeared upon treatment of the polypeptide with endoglycosidase H and N-glycanase. Further tryptic action converted the 27-kDa polypeptide to 2 smaller FITC-labeled polypeptides of 25 and 15 kDa, which lost 18 and 96 amino acid residues, respectively, from the NH2 terminus of the parent polypeptide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence for the presence of a carbohydrate moiety in fluorescein isothiocyanate labeled fragments of rat gastric (H+-K+)-ATPase. 254 51

Our previous studies have shown that the aldose reductase inhibitor (ARI), sorbinil, prevents galactose-induced alterations and cataracts in rat lenses. We have now used sorbinil as well as another ARI, Eisai compound E-0722, to determine their potency in inhibiting aldose reductase- and galactose-induced alterations in lens morphology and Na+-K+-ATPase activity. Young Sprague Dawley rats were fed Purina Rat Chow plus 50% galactose, with or without 15 mg sorbinil, 0.15, 0.5 or 1.0 mg of E-0722/kg body weight per day. Controls were given Purina Rat Chow with or without ARIs. Lenses were studied for up to 60 days following the initiation of the diet using morphological, cytochemical and biochemical approaches to assess any alterations in the lens. While galactose-induced damage and cataracts were delayed by low doses (0.15 mg and 0.5 mg) of E-0722, they were completely prevented by the administration of 15 mg of sorbinil or 1 mg of E-0722/kg body weight per day. This study further showed that just 1 mg of E-0722 was more effective in preventing cataracts than 15 mg sorbinil. Thus it appeared that E-0722 was a more potent inhibitor of aldose reductase than sorbinil.
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PMID:Aldose reductase inhibitors and prevention of galactose cataracts in rats. 254 46

Neuroblastoma cells were used to analyze the effect of galactose supplementation on myo-inositol metabolism, polyol accumulation, and Na+-K+ pump activity. Culturing cells in 30 mM galactose for a minimum of 1 wk led to a large accumulation of intracellular galactitol and a greater than 50% decrease in myo-inositol content. The effect of galactose on the intracellular content of galactitol and myo-inositol was concentration dependent. Extracellular myo-inositol accumulation and incorporation into phospholipid decreased by 20-30% in cells grown in 30 mM galactose. The decrease in myo-inositol accumulation is apparently due to a noncompetitive inhibition of high-affinity myo-inositol uptake. Treatment of the galactose-containing media with 0.4 mM sorbinil partially prevented the galactose-mediated decreases in myo-inositol metabolism and content. The galactitol content of the sorbinil-treated cells was significantly reduced compared with the galactitol levels in cells cultured in 30 mM galactose; however, galactitol levels remained significantly elevated over control cells. Exposing neuroblastoma cells to 30 mM galactose causes a decrease in the levels of phosphatidylinositol that is partially restored by the addition of sorbinil. The activity of the Na+-K+ pump was decreased by 20% in cells cultured in 30 mM galactose and was partially protected by sorbinil treatment. The effects of long-term galactose supplementation on myo-inositol metabolism, polyol accumulation, and Na+-K+-ATPase transport activity in cultured neuroblastoma cells are similar to the effects of high concentrations of glucose. These results provide additional evidence that the accumulation of polyol by neuroblastoma cells is partially responsible for alterations in myo-inositol metabolism and decreases in Na+-K+-ATPase transport activity.
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PMID:Effect of galactose and glucose levels and sorbinil treatment on myo-inositol metabolism and Na+-K+ pump activity in cultured neuroblastoma cells. 254 44

Two enzymatic activities that split diadenosine triphosphate have been reported in Escherichia coli: a specific Mg-dependent bis(5'-adenosyl) triphosphatase (EC 3.6.1.29) and the bis(5'-adenosyl) tetraphosphatase (EC 3.6.1.41). In addition to the activities of these two enzymes, a different enzyme activity that hydrolyzes dinucleoside polyphosphates is described. After purification and study of its molecular and kinetic properties, we concluded that it corresponded to the 5'-nucleotidase (EC 3.1.3.5) that has been described in E. coli. The enzyme was purified from sonic extracts and osmotic shock fluid. From sonic extracts, two isoforms were isolated by chromatography on ion-exchange Mono Q columns; they had a molecular mass of about 100 kilodaltons (kDa). From the osmotic shock fluid, a unique form of 52 kDa was recovered. Mild heating transformed the 100-kDa isoform to a 52-kDa form, with an increase in activity of about threefold. The existence of a 5'-nucleotidase inhibitor described previously, which associates with the enzyme and is not liberated in the osmotic shock fluid, may have been responsible for these results. The kinetic properties and substrate specificities of both forms (52 and 100 kDa) were almost identical. The enzyme, which is known to hydrolyze AMP and uridine-(5')-diphospho-(1)-alpha-D-glucose, but not adenosine-(5')-diphospho-(1)-alpha-D-glucose, was also able to split adenosine-(5')-diphospho-(5)-beta-D-ribose, ribose-5-phosphate, and dinucleoside polyphosphates [diadenosine 5',5'''-P1,P2-diphosphate,diadenosine 5',5'''-P1,P3-triphosphate, diadenosine 5',5'''-P1,P4-tetraphosphate, and bis(5'-guanosyl) triphosphate]. The effects of divalent cations and pH on the rate of the reaction with different substrates were studied.
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PMID:Hydrolysis of bis(5'-nucleosidyl) polyphosphates by Escherichia coli 5'-nucleotidase. 255 71

1. Intracellular Na+ activity (aiNa) has been measured in Purkinje fibres from sheep heart and in ventricular muscle from rabbit heart during hypoxia and metabolic inhibition. The aiNa was measured using liquid sensor ion-sensitive microelectrodes. 2. Hypoxia, produced by replacement of O2 with N2 in the superfusate, produced an increase in aiNa. This increase was larger if sucrose replaced glucose in the superfusing Tyrode solution. The increase in aiNa was accompanied by a small depolarization. Upon reoxygenation aiNa decreased and cells rapidly repolarized. 3. When oxidative phosphorylation was inhibited by application of 2 mM-cyanide, aiNa increased. This increase was also accompanied by a small depolarization. Upon removal of cyanide, aiNa and membrane potential recovered to control levels. 4. After inhibiting glycolysis, by replacing glucose with 2-deoxy-D-glucose, inhibition of oxidative phosphorylation (by addition of cyanide or exposure to hypoxia) produced a much more rapid increase in aiNa and a large contracture. The rise in aiNa and the occurrence of a contracture could not be inhibited by application of amiloride (1 mM) or tetrodotoxin (1 microgram ml-1). Removal of cyanide or reoxygenation and replacement of glucose resulted in a rapid relaxation of the contracture and a slower decrease in aiNa. 5. The relative rates of increase in aiNa during metabolic inhibition were compared with the rate observed when Na+-K+-ATPase was inhibited by application of 10 mumols l-1 of the cardio-active steroid strophanthidin. The rate of increase of aiNa when both oxidative phosphorylation and glycolysis were inhibited was approximately twice that observed with only oxidative phosphorylation inhibited and approximately half that observed in the presence of 10 microM-strophanthidin. 6. Cyanide, applied when aiNa had been elevated (i.e. during exposure to 10 microM-strophanthidin to inhibit Na+-K+-ATPase), did not produce a contracture. The contracture observed in the presence of cyanide and 2-deoxy-D-glucose still occurred when Ca2+ was removed from the superfusate.
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PMID:Effects of hypoxia and metabolic inhibition on the intracellular sodium activity of mammalian ventricular muscle. 255 76

Our recent investigations have shown that the Eisai compound, E-0722, (2R-4S-6-fluoro-1-2-methylspirochroman 4,4'-imidazolidine 2,5'-dione) is a more potent aldose reductase inhibitor than Sorbinil (D-6-fluorospirochroman 4,4'-imidazolidine 2,5'-dione). In the previous studies these aldose reductase inhibitors were added to the 50% galactose diet fed to rats to determine their effect on galactose-induced alterations in the lens and the development of cataract. In this report we present our results on the effect of prefeeding the aldose reductase inhibitor, E-0722, on the alterations in rat lens following subsequent feeding of galactose. For this study, young Sprague Dawley rats were prefed either rat chow or rat chow plus 50% galactose containing 1mg/day/Kg body weight of E-0722 for 1 or 2 weeks. After this dietary regimen, the animals were transferred to diets containing 50% galactose for different periods. For controls, rats were fed either rat chow or 50% galactose without the prefeeding of E-0722. Our results obtained through gross observation of the lenses, light microscopic studies of lens sections and assay of Na+-K+-ATPase (NPPase) activity show that the prefeeding of E-0722 prior to galactose feeding delays galactose-induced alterations and the development of mature cataract.
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PMID:Prefeeding of aldose reductase inhibitor and galactose cataractogenesis. 255 45


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