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:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Beef heart mitochondrial ATPase, in both the membrane-bound and isolated form, contains tightly bound ATP and ADP. Each mol of ATPase contains about 2.2 mol ATP and 1.3 mol ADP. 2. In the absence of ATPase activity, these nucleotides exchange only slowly with nucleotides in solution. The exchange rate is increased during coupled ATPase activity, but not when the ATPase is uncoupled. 3. Oligomycin and dicyclohexylcarbodiimide inhibit exchange of the bound nucleotides, as does the ATPase inhibitor protein, although in each case some residual exchange occurs. Aurovertin, although inhibiting phosphorylation, does not inhibit the exchange. This is discussed in terms of the reversibility of these inhibitors. 4. The stimulation of exchange seen during coupled ATPase activity requires energisation of the ATPase molecule. Using the exchange reaction as a probe of energisation, it is deduced that energy can be transferred between different ATPase molecules. 5. It is proposed that coupled ATPase activity and phosphorylation in submitochondrial particles involve the tight nucleotide binding sites and the (weak) ATPase site, while uncoupled ATPase activity involves only the weak site.
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PMID:Tightly bound nucleotides of the energy-transducing ATPase, and their role in oxidative phosphorylation. II. The beef heart mitochondrial system. 13 63

Purified preparations of F1-ATPase (ATP phosphohydrolase; EC 3.6.1.3) isolated from yeast mitochondria catalyze the reaction of oleoylphosphate with ADP to yield ATP and oleic acid. Formation of ATP is specifically inhibited by the F1-ATPase inhibitor 1799 and by dinitrophenol. In the presence of F1, dinitrophenol "uncouples" the synthase reaction by causing rapid hydrolysis of oleoylphosphate without ATP formation. It is proposed that this F1 catalyzed ATP synthesis reaction corresponds to the terminal chemical step in oxidative phosphorylation.
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PMID:F1-ATPase-catalyzed synthesis of ATP from oleoylphosphate and ADP. 14 17

1. Citreoviridin was a potent inhibitor of the soluble mitochondrial ATPase (adenosine triphosphatase) similar to the closely related aurovertins B and D. 2. Citreoviridin inhibited the following mitochondrial energy-linked reactions also: ADP-stimulated respiration in whole mitochondria from ox heart and rat liver; ATP-driven reduction of NAD+ by succinate; ATP-driven NAD transhydrogenase and ATPase from ox heart submitochondrial particles. 3. The dissociation constant (KD) calculated by a simple law-of-mass-action treatment for the citreoviridin--ATPase complex was 0.5--4.2micron for ox-heart mitochondrial preparations and 0.15micron for rat liver mitochondria. 4. Monoacetylation of citreoviridin decreased its inhibitory potency (KD=2--25micron, ox heart; KD=0.7micron, rat liver). Diacetylation greatly decreased the inhibitory potency (KD=60--215micron, ox heart). 5. Hydrogenation of citreoviridin monoacetate diminished its inhibitory potency considerably. 6. No significant enhancement of fluorescence was observed when citreoviridin interacted with the mitochondrial ATPase.
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PMID:Citreoviridin, a specific inhibitor of the mitochondiral adenosine triphosphatase. 14 74

1. Tightly bound ATP and ADP, found on the isolated mitochondrial ATPase, exchange only slowly at pH 8, but the exchange is increased as the pH is reduced. At pH 5.5, more than 60% of the bound nucleotide exchanges within 2.5 min. 2. Preincubation of the isolated ATPase with ADP leads to about 50% inhibition of ATP hydrolysis when the enzyme is subsequently assayed in the absence of free ADP. This effect, which is reversed by preincubation with ATP, is absent on the membrane-bound ATPase. This inhibition seems to involve the replacement of tightly bound ATP by ADP. 3. Using these two findings, the binding specificity of the tight nucleotide binding sites was determined. iso-Guanosine, 2'-deoxyadenosine and formycin nucleotides displaced ATP from the tight binding sites, while all other nucleotides tested did not. The specificities of the tight sites of the isolated and membrane-bound ATPase were similar, and higher than that of the hydrolytic site. 4. The nucleotide specificities of 'coupled processes' nucleoside triphosphate-driven reversal of electron transfer, nucleoside triphosphate-32Pi exchange and phosphorylation were higher than that of the hydrolytic site of the ATPase and similar to that of the tight nucleotide binding sites.
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PMID:Specificity of nucleotide binding and coupled reactions utilising the mitochondrial ATPase. 15 44

Modification of soluble mitochondrial ATPase (factor F1) by spin-labelled iodoacetamide and spin-labelled methyleneketone does not cause and change in the catalytic properties of the enzyme. The temperature dependence of tau corr. of labels bound to factor F1 testifies to conformational changes in the enzyme at temperatures of 18--20 degrees C and 34--37 degrees C. At these temperature intervals, breaks are observed in the temperature dependence of the ATPase reaction rate in the Arrenius plot. The results obtained indicate that the thermally induced conformational changes in factor F1 affect large areas of the protein molecule. The interaction of factor F1 with the hydrophobic spin probes, namely fatty acid derivatives, was studied. It was shown that the interaction of foctor F1 with Mg2+, Mg-ATP, Mg-ADP and ADP, results in an increase in the ability of the enzyme to adsorb spin probes.
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PMID:[Conformational changes in soluble mitochondrial ATPase by the spin probe method]. 15 72

1. The distribution of ATPase and several marker enzymes was examined after differential and sucrose gradient centrifugation of yeast homogenates. 2. An ATPase activity not sensitive to oligomycin is found exclusively associated with a particulate fraction equilibrating at densities of 1.23-1.25. This particulate material shows the chemical and enzymatic characteristics of the yeast plasma membrane. 3. The pH optimum of the plasma membrane ATPase is 5.6, as compared with 8.5 for the mitochondrial ATPase. In addition to oligomycin, the enzyme is not sensitive to other inhibitors of the mitochondrial ATPase as azide, dicyclohexylcarbodiimide and the mitochondrial ATPase inhibitor protein. It is inhibited by p-chloromercuryphenyl sulfonate, fluoride, quercetin and by the antibiotic Dio-9 but is not affected by ouabain. 4. The plasma membrane ATPase shows a high affinity for ATP (Km = 0.1 mM) and is very specific for this compound, hydrolyzing other nucleotide triphosphates less than 25% as rapidly. No activity was detected with ADP. 5. The enzyme requires a divalent cation for activity and Mg2+ is the most effective. It is not significantly stimulated by K+ or bicarbonate and Ca2+ is inhibitory. 6. The activity cannot be assayed in intact cells unless they are permeabilized with toluene. This suggest that the active site is on the cytoplasmic side of the plasma membrane.
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PMID:Characterization of the plasma membrane ATPase of Saccharomyces cerevisiae. 15 59

The effects of a photoaffinity derivate of ATP, arylazido-beta-alanyl-ATP, 3'-O-(3-[N-(4-azido-2-nitrophenyl)amino]propionyl) adenosine 5'-triphosphate, on submitochondrial particles and the partially purified ATPase complex of beef heart mitochondria have been investigated. In the absence of light the ATP analogue has been found to be a substrate for the E132PA1P1-ATP exchange reaction of submitochondrial particles. When photoirradiated in the presence of arylazido-beta-alanyl-ATP, the ATPase activity and the the the [32P]Pi-ATP exchange reaction are inhibited maximally 80%. Arylazido-beta-alanyl-ATP following photolysis is a noncompetitive inhibitor with respect to ATP while arylazido-beta-alanine, the azido-containing adjunct of the ATP analogue, has no inhibitory effect under the same conditions. The inactivating effect of arylazido-beta-alanyl-ATP is prevented in part by the presence of ATP, or ADP and pyrophosphate. Photolabeling produces a covalent binding of the derivative with the F1ATPase being the major protein labeled. The binding of 0.22 mumol of arylazido-beta-alanyl-ATP/mg of mitochondrial protein is associated with a maximal inhibitory effect. The ATPase activity of the partially purified ATPase complex is also sensitive to photoirradiation in the presence of arylazido-beta-alanyl-ATP. When the ATPase complex is associated with liposomes there is an increase in the specific ATPase activity with a 10-fold increase in Vmax and a 4-fold decrease in KmATP associated with a parallel increase in the apparent affinity and maximal inhibitory effect of the arylazido-beta-alanyl-ATP. The photoinhibition of the ATPase complex in the presence of arylazido-beta-alanyl-ATP results in covalent binding of 1.6 mumol of arylazido-beta-alanyl-ATP/mg of protein. The alpha and beta subunits are the only components of the ATPase complex labeled by the [3H]arylazido-beta-alanyl-ATP. The relationship between the arylazido-beta-alanyl-ATP-labeled sites and the nucleotide binding sites on the mitochondrial ATPase is discussed.
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PMID:The use of arylazido-beta-alanyl-ATP as a photoaffinity label for the isolated and membrane-bound mitochondrial ATPase complex. 15 61

Mixed anhydrides of nucleoside triphosphates and mesitylenecarboxylic acid inhibit soluble mitochondrial ATPase (adenosine triphosphatase), but do not inhibit ATPase of submitochondrial particles. Inhibition of soluble mitochondrial ATPase by the mixed anhydride of epsilon-ATP and mesitylenecarboxylic acid is followed by the covalent binding of one nucleotide residue to a molecule of the protein. It is suggested that this covalent binding occurs in the catalytic site of the mitochondrial ATPase. The mixed anhydride of ADP and mesitylenecarboxylic acid inhibits the ATPase activity of submitochondrial particles and has no effect on the activity of soluble mitochondrial ATPase. After separation of the submitochondrial particles from the mixed anhydride of ADP and mesitylenecarboxylic acid, their ATPase activity is restored to its original value (half-time of reactivation 3--4 min). Incubation of submitochondrial particles or soluble mitochondrial ATPase with the mixed anhydride of ADP and mesitylenecarboxylic acid results in AMP formation.
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PMID:Mixed anhydrides of nucleotides and mesitylenecarboxylic acid as new specific inhibitors of mitochondrial adenosien triphosphatase. 15 22

1. Isolation of ATPase from rat liver submitochondrial particles by chloroform treatment requires the presence of ATP or ADP during enzyme solubilization. In the absence of adenine nucleotides the enzyme activity is very low although all protein components of F1-ATPase are released. The low concentrations of ATP or ADP required (5 microM) indicate that the high affinity nucleotide-binding sites are involved in enzyme stabilization. Other nucleotides tested (ITP, GTP, UTP, CTP) were found to be less effective. 2. Polyacrylamide gel electrophoresis and immunodiffusion in agar plates revealed that in the absence of adenine nucleotides a fraction of F1-ATPase released by chloroform treatment is split into fragments. The part of the dissociated enzyme molecule has a molecular weight identical with that of a beta-subunit of F1-ATPase. 3. Dissociation of the F1-ATPase molecule could also be prevented by aurovertin. 4. Crude F1-ATPase solubilized by chloroform treatment can be further purified by Sepharose 6B gel filtration. Specific ATPase activity of the purified enzyme was 90 mumol Pi/min per mg protein and the enzyme was composed of five protein subunits (alpha, beta, gamma, delta, epsilon) with molecular weights 58 000, 55 000, 28 000, 13 000 and 8000, respectively. 5. Chloroform-released F1-ATPase from rat liver mitochondria displayed immunochemical cross-reactivity with that isolated from beef heart mitochondria.
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PMID:Stabilization of rat liver mitochondrial F1-adenosine triphosphatase during chloroform-induced solubilization. 15 60

1. In addition to the previously studied 8-azido-ATP, 8-azido-ADP is a suitable photoaffinity label for beef-heart mitochondrial ATPase (F1). 2. Photolysis at 350 nm of 8-azido-ADP in the presence of isolated F1 leads to inactivation of ATPase activity. Both ATP and ADP (but not AMP) protect against the inactivation. 3. In the absence of Mg2+, 8-azido-ADP binds almost equally to the alpha and beta subunits of F1, whereas in the presence of Mg2+ the alpha subunits are predominantly labelled. 4. The ATPase activity is completely inhibited when two molecules of 8-azido-ADP are bound per molecule F1. 5. 8-Azido-ATP and ATP are competitive substrates for F1, indicating that in the presence of Mg2+ 8-azido-ATP binds to the same site as ATP. 6. The amount of tightly bound nucleotides in F1 is not significantly changed upon incubation with 8-azido-ATP either in the light or the dark. 7. 8-Azido-ATP is also a suitadrial particles, photolabelling leading to inactivation of ATPase activity. 9. Oxidative phosphorylation and the ATP-driven reduction of NAD+ by succinate are also inhibited by photolabelling Mg-ATP particles with 8-azido-ATP. 10. In contrast to the uncoupled ATPase activity, where the two ATP-binding sites do not interact, cooperation between the two sites is required for ATP hydrolysis coupled to reduction of NAD+ by succinate.
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PMID:Localisation of adenine nucleotide-binding sites on beef-heart mitochondrial ATPase by photolabelling with 8-azido-ADP and 8-azido-ATP. 15 87


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