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)

Methylxanthines (MX) inhibit cell division in sea urchin and clam eggs. This inhibitory effect is not mediated via cAMP. MX also inhibit respiration in marine eggs, at concentrations which inhibit cleavage. Studies showed that no changes occurred in ATP and ADP levels in the presence of inhibitory concentrations of MX, indicating an extra-mitochondrial site of action for the drug. Subsequent studies revealed decreased levels of NADP+ and NADPH, when eggs were incubated with inhibitory concentrations of MX, but no change in levels of NAD+ and NADH. MX did not affect the pentose phosphate shunt pathway and did not have any effect on the enzyme NAD+ -kinase. Further studies showed a marked inhibitory effect on the glutathione reductase activity of MX-treated eggs. Reduced glutathione (GSH) could reverse the cleavage inhibitory effect of MX. Moreover, diamide, a thiol-oxidizing agent specific for GSH in living cells, caused inhibition of cell division in sea urchin eggs. Diamide added to eggs containing mitotic apparatus (MA) could prevent cleavage by causing a dissolution of the formed MA. Both MX and diamide inhibit a Ca2+-activated ATPase in whole eggs. The enzyme can be reactivated by sulfhydryl reducing agents added in the assay mixture. In addition, diamide causes an inhibition of microtubule polymerization, reversible with dithioerythritol. All experimental evidence so far suggests that inhibition of mitosis in sea urchin eggs by MX is mediated by perturbations of the in vivo thiol-disulfide status of target systems, with a primary effect on glutathione levels.
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PMID:Effects of caffeine and other methylxanthines on the development and metabolism of sea urchin eggs. Involvement of NADP and glutathione. 1 15

The presence and some properties of an NAD+ transport system were examined in PA5, a Mg, Ca-ATPase [EC 3.6.1.3]-defective mutant strain of Escherichia coli W2252. NAD+ uptake was stimulated by exogenous energy sources and dependent on external substrate concentrations with an apparent Km of about 25 micrometer. Most of the radioactivity from [14C]-NAD+ accumulated in the cells was identified as NAD+. [14C]NAD+ uptake was competively inhibited by unlabeled NAD+, NADP+, NMN+ or nicotinamide. Similar uptake activity was also observed in W2252.
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PMID:Transport of nicotinamide adenine dinucleotide in an unc mutant of Escherichia coli. 3 59

NAD+ reduction catalyzed by transhydrogenase (EC 1.6.1.1) from E. coli membrane particles at the expense of NADPH oxidation is coupled with phenyldicarbaundecaborate (PCB-) absorption by the particles. This process is inhibited by oxidative phosphorylation protonophorous uncouplers and by equilibration of concentrations of the substrates and products of the transhydrogenase reaction. Elimination of the water-soluble part of membrane ATPase results in the inhibition of PCB- absorption at the expense of the transhydrogenase reaction energy. Treatment of the particles by dicyclohexyl carbodiimide increases the transhydrogenase-coupled absorption of PCB-. The transhydrogenase-induced increase of pPCB in the suspension of particles is directly correlated with the ratio of ([NADPH].[NAD+])/([NADP+].[NADH]). When this value is equal to 1, no energy-dependent increase of pPCB was observed. NADP+ reduction at the expense of NADH oxidation leads to a decrease in the amount of PCB- absorbed by the particles at the expense of ATP hydrolysis energy. The experimental data suggest that NADPH oxidation in the course of the transhydrogenase reaction is coupled with the formation of a membrane potential with a positive charge localized inside the particles.
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PMID:[Transhydrogenase as an additional site of energy accumulation in the E. coli respiratory chain]. 3 31

Three ATP-dependent reactions catalyzed by the inner membrane of rat liver mitochondria and the ATPase reaction catalyzed by purified mitochondrial ATPase (F1), were studied with respect to kinetic properties, substrates specificity, and sensitivity to bicarbonate. The ATP-dependent transhydrogenase reaction (reduction of NADP+ by NADH) catalyzed by inner membrane vesicles displays typical Michaelis-Menten kinetics in both Tris-Cl and Tris-bicarbonate buffers, with Km (ATP) values of 0.035 mM and 0.054 mM respectively. The Vmax of transhydrogenase activity (25 nmol min-1 mg-1) is the same in Tris-bicarbonate or Tris-Cl buffer. ITP and GTP readily substitute for ATP in the transhydrogenase reaction. The ATP-P1 exchange reaction catalyzed by inner membrane vesicles displays typical Michaelis-Menten kinetics in both Tris-Cl and Tris-bicarbonate buffers with Km (ATP) values of 1.0 mM and 1.4 mM respectively. The Vmax of exchange (200 nmol min-1 mg-1) is the same in either buffer. ITP and GTP do not effectively replace ATP in the exchange reaction.
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PMID:ATP-dependent reactions catalyzed by inner membrane vesicles of rat liver mitochondria. Kinetics, substrate specificity, and bicarbonate sensitivity. 17 67

The effect of inhibitors of proton pumps, of uncouplers and of permeant ions on the relationship between input force, delta mu H+, and output flows of the ATPase, redox and transhydrogenase H(+)-pumps in submitochondrial particles was investigated. It is concluded that: (1) The decrease of output flow of the transhydrogenase proton pump, defined as the rate of reduction of NADP+ by NADH, is linearily correlated with the decrease of input force, delta mu H+, in an extended range of delta mu H+, independently of whether the H(+)-generating pump is the ATPase or a redox pump, or whether delta mu H+ is depressed by inhibitors of the H(+)-generating pump such as oligomycin or malonate, or by uncouplers. (2) The output flows of the ATPase and of the site I redox H(+)-pumps exhibit a steep dependence on delta mu H+. The flow-force relationships differ depending on whether the depression of delta mu H+ is induced by inhibitors of the H(+)-generating pump, by uncouplers or by lipophilic anions. (3) With the ATPase as H(+)-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by malonate than by uncouplers; the latter, however, are more inhibitory than lipophilic anions such as ClO4-. With redox site I as proton-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by oligomycin than by uncouplers; again, uncouplers are more inhibitory than ClO4-. (4) The results provide further support for a delocalized interaction of transhydrogenase with other H(+)-pumps.
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PMID:Flow-force relationships during energy transfer between mitochondrial proton pumps. 164 34

Aldose reductase (EC 1.1.1.21) is implicated in the pathophysiology of diabetic complications. In this paper we determined the activities of aldose reductase and ATPases of the erythrocytes in 17 patients with Type 2 (non-insulin-dependent) diabetes mellitus (NIDDM). In the aldose reductase assay we used fluorometric method to avoid the disturbance of hemoglobin. With dihydronicotinamide adenine dinucleotide (NADH), we verified it was aldose reductase but not aldehyde reductase II that was activated in the erythrocytes of the patients with NIDDM. The aldose reductase activity of the erythrocytes in the patients was significantly higher (P less than 0.01) than that in the controls. The activity of Na+/K(+)-ATPase of the patients was significantly lower (P less than 0.01) than that of the controls. The activities of Ca(2+)-ATPase and Mg(2+)-ATPase on the erythrocyte membranes of the patients were similar to those of the controls. At the same time we measured the seven nucleotide concentrations in the erythrocytes of the patients. In this experiment we used ultrafiltration method, instead of acid precipitation to make it possible to determine dihydronicotinamide adenine dinucleotide phosphate (NADPH) and NADH. The concentrations of ATP, ADP and AMP were similar to those of the controls. The concentrations of NADPH, NAD+ and NADH in the erythrocytes of the patients were significantly lower (P less than 0.01, 0.05 and 0.05 respectively) than those of controls. The concentration of nicotinamide adenine dinucleotide phosphate (NADP+) in the patients was significantly higher (P less than 0.01) than that of controls.
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PMID:Activities of aldose reductase, ATPases, and nucleotide concentrations of erythrocytes in patients with type 2 (non-insulin-dependent) diabetes mellitus. 166 Dec 22

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+-adenosine triphosphatase (ATPase) activity in hepatic microsomes was investigated. Mg2+-ATPase activity was clearly increased by the presence of 50 microM Ca2+. Regucalcin (1.0-4.0 microM) caused a remarkable elevation (about 3-fold) of Ca2+-ATPase activity. Also, Mg2+-ATPase activity was increased (about 1.6-fold) by the presence of regucalcin (2.0 and 4.0 microM). Guanosine-5'-O-(3-thiotriphosphate) (GTPrs; 10(-5) and 10(-4) M) and nicotinamide adenine dinucleotide phosphate oxidized form (NADP+; 10(-5) to 10(-3) M) or reduced form (NADPH; 10(-4) and 10(-3) M) significantly increased Ca2+-ATPase activity. These increases were not enhanced by the presence of regucalcin (2.0 microM). Of various metal ions, a comparatively low concentration of V5+ (10(-5) M) or Cd2+ (10(-6) M) significantly increased Ca2+-ATPase activity, while Hg2+, Zn2+, Cu2+ and Mn2+ did not have such an effect. Regucalcin (2.0 microM) did not enhance the effect of V5+ and Cd2+ on Ca2+-ATPase activity. The present finding, that regucalcin activates hepatic microsomal Ca2+-ATPase, suggests a cell physiological role of regucalcin as an activator in the microsomal Ca2+-pump activity. This action of regucalcin may not be influenced by other regulators.
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PMID:Activation of hepatic microsomal Ca2+-adenosine triphosphatase by calcium-binding protein regucalcin. 252 22

A simple and fast ion pair reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of ATP, ADP, AMP, GTP, GDP, IMP, NADP+, NADPH+, NAD+, NADH, ADP-ribose, inosine, adenosine, hypoxanthine, and xanthine. This method allows us to have a complete picture of the most important nucleotides present in fresh human erythrocytes. Furthermore it is particularly useful in the study of the erythrocyte adenine nucleotide catabolism allowing the detection of degradation products such as IMP, inosine, adenosine, hypoxanthine, and xanthine. The separation of the compounds under investigation is achieved in less than 15 min using a reversed-phase 3-micron Supelcosil LC-18 column and adding tetrabutylammonium, as ion-pair agent, to the buffers. The short time of analysis, the high reproducibility of the system, and the accurate evaluation of the compounds of interest make this method particularly suitable for routine analysis. Finally it is possible to use this assay as an alternative method of measuring activities of enzymes which catalyze reactions involving some of these compounds, as in the case of Na+-K+ ATPase, AMP deaminase, and adenosine deaminase.
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PMID:A very fast ion-pair reversed-phase HPLC method for the separation of the most significant nucleotides and their degradation products in human red blood cells. 282 56

Effects of the antiarrhythmic drugs (propranolol, perhexiline maleate, lidoflazine and iproveratril) on energy-linked reactions and on membrane potential were studied. Propranolol, perhexiline maleate and lidoflazine inhibit the ATPase activity of undamaged and broken mitochondria, and of submitochondrial particles. All drugs are inhibitors of either ATP-driven or of succinate-driven reduction of NADP+. The antiarrhythmics promote a decrease in the membrane potential upon energization of the mitochondrial membrane by alpha-ketoglutarate, succinate, or ATP. It was suggested that these drugs have a primary action on the mitochondrial membrane, thus altering the activities of membrane proteins (channels and enzymes).
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PMID:Biochemical aspects of the mechanism of action of antiarrhythmic drugs on mitochondria. VII. Effect on energy-linked reactions and on membrane potential. 287 37

An ion-pair, reverse-phase, high-performance liquid chromatography method of assay was developed and used in a series of rate studies carried out with the enzyme chicken liver NAD+ kinase (ATP:NAD+ 2'-phosphotransferase, EC 2.7.1.23). Complete separation of all products and reactants was achieved within 15 min. ATP, NAD+, ADP, and NADP+ were monitored at 260 nm as they eluted from a Zorbax (Dupont) ODS (4.6 X 250-mm) column using an acetonitrile and 0.01 mM NH4(H2PO4)/0.005 M tetrabutylammonium phosphate (pH 7.0) gradient. The enzyme shows a marked preference for ATP (and dATP) and Mg2+ (or Mn2+) relative to other trinucleotides and divalent metal ions. It exhibits residual adenylate kinase and ATPase activity, but no NADH kinase activity. When polyphosphate replaced ATP, NADP+ production dropped to 2.5%. The addition of Ca2+ and/or bovine brain calmodulin did not significantly enhance the rate of NADP+ production.
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PMID:Ion-pair reverse-phase high-performance liquid chromatography. Application to the study of chicken liver NAD+ kinase. 300 Feb 15


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