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)

Mitochondrial ATPase from rat liver mitochondria contains multiple nucleotide binding sites. At low concentrations ADP binds with high affinity (1 mole/mole ATPase, KD = 1-2 muM). At high concentrations, ADP inhibits ATP hydrolysis presumably by competing with ATP for the active site (KI = 240-300 muM). As isolated, mitochondrial ATPase contains between 0.6 and 2.5 moles ATP/mole ATPase. This "tightly bound" ATP can be removed by repeated precipitations with ammonium sulfate without altering hydrolytic activity of the enzyme. However, the ATP-depleted enzyme must be redissolved in high concentrations of phosphate to retain activity. AMP-PNP (adenylyl imidodiphosphate) replaces tightly bound ATP removed from the enzyme and inhibits ATP hydrolysis. AMP-PNP has little effect on high affinity binding of ADP. Kinetics studies of ATP hydrolysis reveal hyperbolic velocity vs. ATP plots, provided assays are done in bicarbonate buffer or buffers containing high concentrations of phosphate. Taken together, these studies indicate that sites on the enzyme not directly associated with ATP hydrolysis bind ATP or ADP, and that in the absence of bound nucleotide, Pi can maintain the active form of the enzyme.
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PMID:Interaction of homogeneous mitochondrial ATPase from rat liver with adenine nucleotides and inorganic phosphate. 12 85

1. The synthesis of dibutylchloromethyltin chloride, a new covalent inhibitor of the mitochondrial ATP synthase [oligomycin-sensitive ATPase (adenosine triphosphatase)] complex is described, together with a method for preparing dibutylchloro[(3)H]methyltin chloride. 2. Studies with the yeast mitochondrial oligomycin-sensitive ATPase complex show that dibutylchloromethyltin chloride inhibits both the membrane-bound enzyme and also the purified Triton X-100-dispersed preparation. 3. F(1)-ATPase is not inhibited even at 500nmol of dibutylchloromethyltin chloride/mg of protein, and the general inhibitory properties are similar to those of triethyltin, oligomycin and dicyclohexylcarbodi-imide, known energy-transfer inhibitors of oxidative phosphorylation. 4. Binding studies with yeast submitochondrial particles show that dibutylchloromethyltin chloride antagonizes the binding of triethyl[(113)Sn]tin, indicating that there is an interaction between the two inhibitor-binding sites. 5. Unlike triethyltin, inhibition by dibutylchloromethyltin chloride is due to a covalent interaction which titrates a component of the inner mitochondrial membrane present at a concentration of 8-9nmol/mg of protein. 6. All of the labelled component can be extracted with chloroform/methanol (2:1, v/v), and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the chloroform/methanol extract indicates that the labelled component has an apparent mol.wt. of 6000-8000. However, t.l.c. reveals the presence of only one labelled component which is lipophilic and non-protein and is distinct from the free inhibitor, mitochondrial phospholipids and the dicyclohexylcarbodi-imide-binding protein (subunit 9). 7. Inhibition of mitochondrial ATPase and oxidative phosphorylation is correlated with specific interaction with a non-protein lipophilic component of the mitochondrial inner membrane which is proposed to be a co-factor or intermediate of oxidative phosphorylation.
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PMID:Dibutylchloromethyltin chloride, a covalent inhibitor of the adenosine triphosphate synthase complex. 14 60

The parameters of the hydrolysis of ATP and several analogs by soluble mitochondrial ATPase were determined. Vmax of the reaction decreases within the range: 2'-desoxy-ATP greater than ATP greater than etheno-ATP greater than GTP greater than 3'-O-methylATP greater than UTP. ATP, 2'-desoxypATP, 3'O-methyl-ATP, GTP, and etheno-ATP are hydrolysed by soluble mitochondrial ATPase with close Km(app) values. CTP is not hydrolysed by the enzyme and does not inhibit the ATPase reaction at a concentration of 10(-2) M. Nucleoside triphosphate derivatives with an "open" ribose cycle 9-[1',5'-dihydroxy-4-(S)-hydroxymethyl-3'-oxapent-2' (R)-yl]adenyl-5'-triphosphate, and 1-[1',5'-dihydroxy-4'-(S)-hydroxymethyl-3'-oxapent-2'(R)-yl[cytosine-5'-triphosphate are effective inhibitors of ATPase (Ki approximately 5.10(-5)M). Mitochondrial ATPase binds the ATP analogs that have hydrocarbon radicals-(CH2)2-, -(CH2)3-, and (CH2)4- instead of the ribose residues: 9-(2'hydroxyethyl)adenyl-2'-triphosphate, 9-(3'-hydroxypropyl)-adenine-3'-triphosphate, and 9-(4'-hydroxybutyl)adenine-4'-triphosphyl)adenine-4'-triphosphate were not hydrolysed by the enzyme, although they inbibit the ATPase reaction (Ki 2.10(-4)M). 9-(2'-hydroxyethyl)adenine-2'-triphosphate is hydrolysed by ATPase eight times more slowly than ATP. It is suggested that the hydrolysis of the substrates of mitochondrial ATPase is- preceded by the binding of the substrates in a tense conformation in the active site of the enzyme.
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PMID:[Substrate specificity of soluble mitochondrial ATPase]. 14 22

The effect of thyroxine administration upon ATPase activity of several subcellular fractions of livers from rats and guinea pigs has been studied. To determine a patho-physiological dose of levo thyroxine [T4] for guinea pigs, a dose-response curve was examined of T4 effect upon oxidative phosphorylatin of guinea pig liver mitochondria. Maximum stimulation of mitochondrial respiration without uncoupling of oxidative phosphorylation was found with 15 microgram of T4 per 100 g body weight per day. This dose of T4 stimulated Mg++ activated ATPase of plasma membranes of guinea pigs and slightly stimulated Mg++ activated ATPase of guinea pig liver nuclear membranes. Rat liver nuclear membrane ATPase was not responsive to thyroxine at doses from 5 to 150 microgram per 100 g body weight. T4 significantly stimulated Ca++ or Mg++ ATPase of mitochondria and microsomes from both rat and guinea pig liver. Microsomes from both species were maximally activated by Mg++ and no significant additional stimulation with Ca++ was found. Mitochondrial ATPase from both species showed significantly greater Ca++ plus Mg++ ATPase activity than did Mg++ alone. Ca++ activated ATPase was approximately equal to dinitrophenol stimulated mitochondrial ATPase. Maximum activation of microsomal ATPase in both species was found with 1 mM calcium. We conclude that at physiological-intracellular concentrations of Ca++ and Mg++, thyroxine probably stimulates Mg++ activated microsomal ATPase and Ca++ activated mitochondrial ATPase. A potential role of Ca++ as a moderator of thyroxine stimulated activity in mitochondria and the relation of calcium to other metabolic reactions that are thyroxine sensitive is discussed.
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PMID:L-Thyroxine effects upon ATPase activities of several subcellular fractions of liver of the rat and the guinea pig. 16 Sep 23

The effect of temperature on the activation energies of mitochondrial enzymes of the yeast Saccharomyces cerevisiae was examined. Non-linear Arrhenius plots with discontinuities in the temperature range 14-19 degrees C and 19-22 degrees C were observed for the respiratory enzymes and mitochondrial ATPase (adenosine triphosphatase) respectively. A straight-line Arrhenius plot was observed for the matrix enzyme, malate dehydrogenase. The activation energies of the enzymes associated with succinate oxidation, namely, succinate oxidase, succinate dehydrogenase and succinate-cytochrome c oxidoreductase, were in the range 60-85kJ/mol above the transition temperature and 90-160kJ/mol below the transition temperature. In contrast, the corresponding enzymes associated with NADH oxidation showed significantly lower activation energies, 20-35kJ/mol above and 40-85kJ/mol below the transition temperature. The discontinuities in the Arrhenius plots were still observed after sonication, treatment with non-ionic detergents or freezing and thawing of the mitochondrial membranes. Discontinuities for cytochrome c oxidase activity were only observed in freshly isolated mitochondria, and no distinct breaks were observed after storage at -20 degrees C. Mitochondrial ATPase activity still showed discontinuities after sonication and freezing and thawing, but a linear plot was observed after treatment with non-ionic detergents. The results indicate that the various enzymes of the respiratory chain are located in a similar lipid macroenvironment within the mitochondrial membrane.
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PMID:Phase transitions in yeast mitochondrial membranes. The effect of temperature on the energies of activation of the respiratory enzymes of Saccharomyces cerevisiae. 16 75

Mitoplasts, that is, mitochondria freed from their outer membranes, were prepared from pig heart. Sonication induced an inversion of these mitoplasts, giving inside-out vesicles. Added cytochrome c can be bound much better to mitoplasts than to sonicated vesicles; addition of trypsin increased adenosinetriphosphatase (ATPase) (ATP phosphohydrolase; EC 3.6.1.3) activity of sonicated vesicles without significantly affecting that of the mitoplasts. Since the site of fixation of cytochrome c was located on the outer side of the inner mitochondrial membrane and since the protein inhibitor of the mitochondrial ATPase is present on the inner face of the inner membrane and is very sensitive to trypsin, it can be concluded that mitoplasts are mainly oriented as normal mitochondria while sonicated vesicles are mainly inverted. Trypsin treatment can abolish the oligomycin sensitivity of ATPase activity of either mitoplasts or sonicated vesicles. However, trypsin induced the solubilization of the soluble F(1)-ATPase of sonicated vesicles while the ATPase activity remained with the mitoplasts after trypsin action. Therefore, trypsin destroyed the oligomycin effect by rupturing the liaison between F(1) and the membrane in sonicated vesicles. On the other hand, the effect of trypsin on mitoplasts must be attributed to the hydrolysis of a protein located near the outer surface of the inner membrane that is at least structurally involved in the oligomycin sensitivity of the ATPase complex.
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PMID:Location of protein(s) involved in oligomycin-induced inhibition of mitochondrial adenosinetriphosphatase near the outer surface of the inner membrane. 20 Sep 6

Mitochondrial ATPase complex has been spin-labeled in the membrane using the inhibitor N-(2,2,6,6-tetramethylpeperidyl-1-OXYL)-N(cyclohexyl)carbodiimide (nccd). the amount of NCCD bound to mitochondrial fragments is 0.5 nmol/mg and cannot be dialyzed or extracted with ether, chloroform, or methanol. The electron paramagnetic resonance spectrum of NCCD bound to fragments is pH-sensitive, a greater label immobilization occurring at pH values lower or higher than 7. Ether extraction removes the ATPase inhibition by NCCD without detaching the label. This effect appears to be the consequence of the dislocation of some components of the ATPase complex. Removal of F1 natural inhibitor or of F1 does not affect the spectrum of NCCD bound to fragments, while the removal of oligomycin sensitivity-conferring protein produces an increase in the extreme splitting. Oligomycin sensitivity-conferring protein may thus interact with the NCCD binding component of the membrane. The isolation of the NCCD-binding proteolipid results in a large increase in the mobility of the label, but addition of dipalmitoyllecithin decreases the mobility of the label to the original level. Phospholipids are thus necessary to keep the NCCD-binding proteolipid in the native conformation.
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PMID:Molecular interactions of adenosine triphosphatase with the mitochondrial membrane as revealed by a spin label study. 23 75

Studies of the effect of strophanthidin on H(+)-transporting ATPase, Ca(2+)-transporting ATPase and H+/K(+)-transporting ATPase activities are reported. Inhibition observations and kinetic results suggest the existence of a common digitalis aglycone binding site located on the extracellular surface of the enzyme, which is affected competitively by the binding of potassium to H(+)-transporting ATPase, Ca(2+)-transporting ATPase, as well as H+/K(+)-transporting ATPase and Na+/K(+)-transporting ATPase. This may lead to a better understanding of the mechanism of the pharmacological action of cardiac glycosides and imply the possibility that the positive inotropic effect may result from the inhibition of both Ca(2+)-transporting ATPase and Na+/K(+)-transporting ATPase.
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PMID:Inhibition of H(+)-transporting ATPase, Ca(2+)-transporting ATPase and H+/K(+)-transporting ATPase by strophanthidin. 132 54

Oxyphil cells are characterized by cytoplasm packed with large numbers of mitochondria. Study of these unusual cells may provide information about the regulation of mitochondrial biogenesis. Although it has been suggested that this is a compensatory proliferation due to a mitochondrial dysfunction, no such dysfunction has been well documented. In this study we considered the possibility of dysfunction in the mitochondrial enzyme F1/Fo-adenosine triphosphatase(ATPase) as a stimulating factor involved in the mitochondrial proliferation of oxyphil cells. Mitochondria isolated from frozen tissue of a renal oncocytoma showing structural integrity and purity by electron microscopy were studied. Submitochondrial particles formed by sonic disruption showed the presence of the F1 component of mitochondrial ATPase with electron microscopy which was functionally active. The oligomycinsensitive ATPase activity from the renal oncocytoma was 0.133 mumol/min.mg submitochondrial particle protein which was higher than the readings obtained from normal kidney tissue (0.091 mumol/min.mg SMP protein) obtained from hamsters. Normal human renal tissue obtained at autopsy contained only nonfunctional mitochondria and therefore could not be used as control tissue. Mitochondrial ATPase dysfunction does not appear to be the inciting factor in the proliferation of mitochondria seen in oxyphil cell metaplasia and future studies should consider other possibilities. Preliminary functional studies of this nature can be performed with properly prepared frozen surgical tissue.
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PMID:Mitochondrial adenosine triphosphatase in the oxyphil cells of a renal oncocytoma. 213 85

Chloroplast ATPase complex is activated by illumination in the presence or absence of dithiothreitol. ATPase complex which has been activated without dithiothreitol catalyzes ATP hydrolysis which is insensitive to stimulation by NH4Cl and is highly sensitive to medium pH. Addition of dithiothreitol during illumination results in an increase in the stimulating effect of NH4Cl on ATP hydrolysis and a decrease in pH sensitivity of ATP hydrolysis. With increasing time in the dark, the ability of NH4Cl to stimulate ATP hydrolysis decreases and the effect of pH on the ATP hydrolysis increases. The onset of resistance to NH4Cl stimulation and the increase in sensitivity to pH are accelerated by ADP and the acceleration is inhibited by Pi. ATP hydrolysis restores NH4Cl sensitivity and renders the activity more resistant to pH. These results suggest that active chloroplast ATPase complex converts its state reversibly from the NH4Cl-insensitive and highly pH-sensitive one to the NH4Cl-sensitive and relatively pH-insensitive one. The conversion from the former to the latter requires both sulfhydryl compound and energy.
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PMID:Interconversion of two distinct states of active CF0-CF1 (chloroplast ATPase complex) in chloroplasts. 286 97


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