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)

Beef heart mitochondrial ATPase (F1) exhibited a single binding site for Pi. The interaction with Pi was reversible, partially dependent on the presence of divalent metal ions, and characterized by a dissociation constant at pH 7.5 of 80 micronM. A variety of substances known to influence oxidative phosphorylation or the activity of the soluble ATPase (F1) also influenced Pi binding by the enzyme. Thus aurovertin, an inhibitor of oxidative phosphorylation, which was bound tightly by F1 and inhibited ATPase activity, enhanced Pi binding via a 4-fold increase in the affinity of the enzyme for Pi (KD = 20 micronM) but did not alter binding stoichiometry. Anions such as SO4(2-), SO3(2-), chromate, and 2,4-dinitrophenolate, which stimulated ATPase activity of F1, also enhanced Pi binding. Inhibitors of ATPase activity such as nickel/bathophenanthroline and the protein ATPase inhibitor of Pullman and Monroy (Pullman, M. E., and Monroy, G. C. (1963) J. Biol. Chem. 238, 3762-3769) inhibited Pi binding. The adenine nucleotides ADP, ATP, and the ATP analog adenylyl imidodiphosphate as well as the Pi analog arsenate, also inhibited Pi binding. The observations suggest that the Pi binding site was located in or near an adenine nucleotide binding site on the molecule.
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PMID:Reversible binding of Pi by beef heart mitochondrial adenosine triphosphatase. 1 6

Vesicles were reconstituted from a purified dicyclohexyl-carbodiimide-sensitive ATPase complex (TF0-F1) and phospholipids of a thermophilic bacterium PS3. These vesicles synthesized ATP from ADP and Pi with energy from an electrochemical proton gradient (delta-micronH+) formed by a pH gradient and an electrical potential across their membranes. Maximal ATP synthesis was achieved by incubating the vesicles in malonate at pH 5.5 with valinomycin, and then rapidly transferring them to a solution of pH 8.4 and 150 mM K+. Under these conditons ATP synthesis continued at a decreasing rate for 30 s at 40 degrees. Appreciable formation of ATP (40 to 150 nmol/mg of TF0-F1) occurred at an initial delta-micronH+ above 205 mV and moderate formation at an initial value above 180 mV. ATP hydrolysis by the vesicles produced a delta-micronH+, and the additions of 32Pi and hexokinase to them resulted in 32Pi esterification. Analysis of the time courses of 32Pi esterification and decays of the pH difference and membrane potential, followed using 9-aminoacridine and 8-anilinonaphthalene-1-sulfonate, respectively, as probes, showed a relationship between delta-micronH+ and the rate of ATP synthesis. These results demonstrate that purified TF0-F1 is itself a reversible H+-translocating ATPase of oxidative phosphorylation.
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PMID:Adenosine triphosphate synthesis by electrochemical proton gradient in vesicles reconstituted from purified adenosine triphosphatase and phospholipids of thermophilic bacterium. 1 11

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

In sarcoplasmic reticulum of rabbit skeletal muscles the activity of Ca2+, Mg2+- dependent ATPase was distinctly inhibited under effect of neuroleptic drugs - derivatives of phenothiazine and butyrophenone. The effect of tricyclic antidepressants was less pronounced. Tranquilizers (derivatives of 1,4-benzodiazepine) inhibited the enzyme, but trioxazin was only slightly active. High concentrations of lithium salts and of psychostimulants caffeine and corasole were found to stimulate the Ca2+, Mg2+-ATPase activity; low concentrations of the substances slightly inhibited the enzyme. The blocking effect of psychotropic drugs was more distinct, if the enzyme preparations were previously treated with ATP.
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PMID:[Effect of psychotropic preparations on the activity of Ca- and Mg-dependent ATPase of the sarcoplasmic reticulum]. 1

It has been proposed (Slayman, C.L., Long W.S., and Lu, C.Y.-H. (1973) J. Membr. Biol. 14, 305--338) that in Neurospora crassa, a plasma membrane ATPase functions to pump H+ ions out of the cell, thereby generating an electrochemical gradient that can drive transport processes. Using the concanavalin A method of Scarborough (Scarborough G.A. (1975)J. Biol. Chem. 250, 1106--1111), we have prepared plasma membranes of Neurospora and have deomonstrated that they do contain a distinct ATPase activity with the following properties. It has a pH optimum of 6.0, is highly specific for ATP (hydrolyzing other nucleoside triphosphates less than 6% as rapidly), requires Mg2+ at concentrations approximately equimolar to the concentration of ATP, is weakly stimulated by certain monovalent cations (K+ and NH4+) and anions (SCN- and acetate), is inhibited by N,N'-dicyclohexylcarbodiimide, but is not affected by oligomycin or ouabain. The plasma membrane fraction also contains residual mitochondrial contamination, which can be determined quantitatively by assaying oligomycin-sensitive ATP-ase activity, at pH 8.25, and succinic dehydrogenase activity.
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PMID:Characterization of plasma membrane adenosine triphosphatase of Neurospora crassa. 1 97

A vesicular microsomal fraction isolated from hog fundic mucosa demonstrates the capacity to take up equal amounts of RB+ and Cl-. The amount of the Rb+ uptake is sensitive to the extravesicular osmolarity, and rate of uptake is sensitive to temperature. 86Rb+ efflux is dependent upon the cation composition of the diluting solution. ATP, but not beta-gamma methylene ATP, induces a reversible efflux of 86Rb+ from loaded vesicles, and this is dependent upon a functional K+-ATPase. The ATP induced efflux is not affected by CCCP (carbonyl cyanide m-chlorophenylhydrazone) or TCS (tetrachlorosalicylanilide) nor by lipid soluble ions or valinomycin. Nigericin inhibits the efflux by 40%. Uptake of the lipid soluble ion 14C-SCN- has been demonstrated and is enhanced by ATP only in the presence of valinomycin. The results are consistent with a neutral or isopotential exchange of H+ for Rb+ mediated by K+-ATPase.
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PMID:Cation transport by gastric H+:K+ ATPase. 1 7

The stoichiometry of H+ ejection by mitochondria during hydrolysis of a small pulse of ATP (the H+/ATP ratio) has been reexamined in the light of our recent observation that the stoichiometry of H+ ejection during mitochondrial electron transport (the H+/site ratio) was previously underestimated. We show that earlier estimates of the H+/ATP ratio in intact mitochondria were based upon an invalid correction for scaler H+ production and describe a modified method for determination of this ratio which utilizes mersalyl or N-ethylmaleimide to prevent complicating transmembrane movements of phosphate and H+. This method gives a value for the H+/ATP ratio of 2.0 without the need for questionable corrections, compared with a value of 3.0 for the H+/site ratio also obtained by pulse methods. A modified version of the chemiosmotic theory is presented, in which 3 H+ are ejected per pair of electrons traversing each energy-conserving site of the respiratory chain. Of these, 2 H+ return to the matrix through the ATPase to form ATP from ADP and phosphate, and 1 H+ returns through the combined action of the phosphate and adenine nucleotide exchange carriers of the inner membrane to allow the energy-requiring influx of Pi and ADP3- and efflux of ATP4-. Thus, up to one-third of the energy input into synthesis of extramitochondrial ATP may be required for transport work. Since other methods suggest that the H+/site significantly exceeds 3.0, an alternative possibility is that 4 h+ are ejected per site, followed by return of 3 H+ through the ATPase and 1 H+ through the operation of the proton-coupled membrane transport systems.
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PMID:H+/ATP ratio during ATP hydrolysis by mitochondria: modification of the chemiosmotic theory. 1 16

1. Preincubation with N-ethylmaleimide inhibits the overall activity of highly purified (Na+ +K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) preparations of rabbit kidney outer medulla. 2. This inhibition is decreased by addition of ATP or 4-nitrophenylphosphate under non-phosphorylating conditions, and also by addition of ADP or adenylylimidodiphosphate. 3. N-ethylmaleimide treatment leads to inhibition of K+-stimulated 4-nitrophenylphosphatase activity, Na+-stimulated ATPase activity, and phosphorylation by ATP as well as by inorganic phosphate. These inhibitions strictly parallel that of the overal (Na+ +K+)-ATPase reaction. 4. N-ethylmaleimide lowers the number of sites which are phosphorylated by inorganic phosphate, without affecting the dissociation constant of the enzyme-phosphate complex. 5. N-ethylmaleimide does not affect the relative stimulation by ATP of the K+-stimulated 4-nitrophenylphosphatase activity. 6. These effects of N-ethylmaleimide can be explained as a complete loss of active enzyme, either by reaction of N-ethylmaleimide inside the active center, or by alterations in the quaternary structure through reactions outside the active center.
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PMID:Studies on (Na+ +K+) activated ATPase. XLI. Effects of N-ethylmaleimide on overall and partial reactions. 1 94

Biochemical and cytochemical techniques were used to determine whether oviduct basal bodies have ATPase activity. All studies were carried out on basal bodies isolated and purified from the chicken oviduct. These preparations contained structurally intact basal bodies with basal feet, rootlet, and alar sheet accessory structures. Whereas the specific activity of the basal body ATPase in 2 mM Ca++ or 2 mM Mg++, 1 mM ATP, pH 8.0, averaged 0.04 mumol Pi/min per mg protein, higher concentrations of either cation inhibited the enzyme activity. Furthermore, the pH optimum for this reaction was pH 8.5. In comparison, the ATPase activity in cilia purified and measured under conditions identical to those for determining the basal body ATPase activity averaged 0.07 mumol Pi/min per mg protein. However, the activity increased at higher concentrations of divalent cation, and the pH optimum was pH 10.0. By cytochemical procedures for localizing ATPase activity, ATP-dependent reaction product in isolated basal bodies was found to be confined to: (a) the cross-striations of the rootlet; (b) the outer portion of the basal foot; (c) the alar sheets; and (d) the triplet microtubules. It is concluded that basal bodiesve an intrinsic ATPase activity that, by a variety of criteria, can be distinguished from the ATPase activity found in cilia.
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PMID:Biochemical and cytochemical evidence for ATPase activity in basal bodies isolated from oviduct. 1 79

The HCO-3-stimulated Mg2+ -ATPase activity in red cell ghost fragments was investigated. Increasing the HCO-3 concentration in the incubation medium resulted in increased ATPase activity. NaHCO3 appeared to be more effective than KHCO3 in this regard. The ATPase activities were slightly stimulated by increases in ionic strength and utilized ITP almost as readily as ATP. A Mg/ATP ratio of 1.0 and a pH of 7.6 yielded maximum activity. These properties are of interest since the present enzyme is the only unquestionable instance where a HCO-3 ATPase is located in the surface membrane of a cell.
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PMID:Properties of the HCO-3-stimulated Mg2+ -ATPase activity in red cell membranes. 1 3


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