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. A formula is given that describes the appearance of [14C]ATPADP outside the mitochondria after the addition of [14C] 1atp during the steady-state uncoupler-induced hydrolysis of extramitochondrial ATP. If the transported adenine nucleotides equilibrate with the intramitochondrial pool, [14C]ADP0 would be expected to appear with a lag phase that corresponds with the time needed for the radioactive labelling of the intramitochondrial adenine nucleotide pool. 2. The rates of formation of [14C]ADP outside the mitochondria after addition of [14C]ATP during the steady-state uncoupler-induced ATP hydrolysis catalysed by rat-liver mitochondria at 0 degree C were measured. 3. In the presence of carbonyl cyanide m-chlorophenylhydrazone the time course of the [14]ADPo formation was the same as that predicted on the basis of the above assumption. 4. In the presence of the less effective uncoupler, 2,4-dinitrophenol, the time course of [14C]ADPo formation was not consistent with the theoretical predictions: no lag phase was present and the measured rate was higher than the maximal calculated rate. These results can be explained by assuming a functional interaction between the adenine nucleotide translocator and the mitochondrial ATPase (F1). 5. It is concluded that under phosphorylating as well as dephosphorylating conditions, the adenine nucleotide translocator and the mitochondrial ATPase can be functionally linked to catalyse phosphorylation or dephosphorylation of extramitochondrial ADP or ATP, without participation of the intramitochondrial adenine nucleotides.
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PMID:Role of the intramitochondrial adenine nucleotides as intermediates in the uncoupler-induced hydrolysis of extramitochondrial ATP. 13 45

The effects of various substrates and alternative substrates on the hydrolytic activity of beef heart mitochondrial ATPase was examined. It was found that ATP or ADP, ITP hydrolysis showed positive cooperativity. IDP inhibited ITP hydrolysis and caused positive cooperativity. When ITP was present during an ATP hydrolysis assay, the rate of ATP hydrolysis was stimulated. IDP had no effect on ATP hydrolysis rates. A nonhydrolyzable ITP analog, inosine 5'-(beta, gamma-imido)triphosphate (IMP-P(NH)P), was synthesized and purified. It was found to be a potent competitive inhibitor of ITP and GTP hydrolytic activity. However, this beta-gamma-imido-bridged ITP analog was found to change the ITP and GTP hydrolysis kinetics from linear to positively cooperative. This compound inhibited ATP hydrolysis at substrate concentrations of 100 muM and lower, and stimulated ATP hydrolysis at substrate concentrations between 100 muM and 2 mM. IMP-P(NH)P had no effect on ATP hydrolysis when the substrate concentration was above 2 mM. In the presence of the activating anion, bicarbonate, IMP-P(NH)P inhibited ATP hydrolysis competitively, and induced positive cooperativity. IMP-P(NH)P had no effect on the ATP equilibrium Pi exchange, the ITP equilibrium Pi exchange, or ATP synthesis catalyzed by beef heart submitochondrial particles.
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PMID:Effect of inosine 5' -(beta, gamma-imido) triphosphate and other nucleotides on beef heart mitochondrial ATPase. 13 64

Soluble mitochondrial ATPase (F1) from beef heart prepared in this laboratory contained approximately 1.8 mol of ADP and 0 mol of ATP/mol of F1 which were not removed by repeated precipitation of the enzyme with ammonium sulfate solution or by gel filtration in low ionic strength buffer containing EDTA. This enzyme had full coupling activity. Treatment of the enzyme with trypsin (5 mug/mg of F1 for 3 min) reduced the "tightly bound" ADP to zero, abolished coupling activity, but had no effect on the ATPase activity, stability, or membrane-binding capability of the F1. When the trypsin concentration was varied between 0 and 5 mug/mg of F1, tightly bound ADP was removed to varying degrees, and a correlation was seen between amount of residual tightly bound ADP and residual coupling activity. Gel filtration of the native F1 in high ionic strength buffer containing EDTA also caused complete loss of tightly bound ADP and coupling ability, whereas ATPase activity, stability, and membrane-binding capability were retained. The ADP-depleted F1 preparations were unable to rebind normal amounts of ADP or any ATP in simple reloading experiments. The results strongly suggest that tightly bound ADP is required for ATP synthesis and for energy-coupled ATP hydrolysis on F1. The results also suggest that ATP synthesis and energy-linked ATP hydrolysis rather than involving one nucleotide binding site on F1, involve a series or "cluster" of sites. The ATP hydrolysis site may represent one component of this cluster. The results show that nonenergy-coupled ATP hydrolysis on F1 can occur in the absence of tightly bound ADP or ATP.
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PMID:Removal of "tightly bound" nucleotides from soluble mitochondrial adenosine triphosphatase (F1). 13 45

ATP synthase preparations [complex V, proton-translocatin ATPase (adenosine triphosphatase) and oligomycin-sensitive ATPase ] contain stoicheiometric amounts of lipoic acid residues (up to 6mol of lipoic acid/mol of ATPase complex) and catalyse net ATP synthesis in an uncoupler-and oligomycin-sensitive reaction utilizing dihydrolipoate, oleoyl-CoA and oleic acid, or in a reaction utilizing oleoyl-S-lipoate. The terminal reactions of oxidative phosphorylation are thus analogous to those of substrate-level phosphorylation.
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PMID:Studies of energy-linked reactions. Net synthesis of adenosine triphosphate by isolated adenosine triphosphate synthase preparations: a role for lipoic acid and unsaturated fatty acids. 13 19

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

1. Stimulation of the Escherichia coli ATPase activity by urea and trypsin shows that the ATPase activity both in the membrane-bound and the solubilized form is partly masked. 2. A protein, inhibiting the ATPase activity of Escherichia coli, can be isolated by sodium dodecyl sulphate polyacrylamide gel electrophoresis of purified ATPase. The inhibitor was identified with the smallest of the subunits of E. coli ATPase. 3. The molecular weight of the ATPase inhibitor is about 10,000, as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis and deduced from the amino acid composition. 4. The inhibitory action is independent of pH, ionic strength or the presence of Mg2+ or ATP. 5. The ATPase inhibitor is heat-stable, insensitive to urea but very sensitive to trypsin degradation. 6. The Escherichia coli ATPase inhibitor does not inhibit the mitochondrial or the chloroplast ATPase.
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PMID:Isolation and characterization of an inhibitory subunit of the Mg2+--Ca2+-ATPase of Escherichia coli. 13 64

1. 8-Azido-ATP is a suitable photoaffinity label for beef-heart mitochondrial ATPase (F1) 2. 8-Azido-ATP is hydrolysed slowly by F1 in the dark. Photolysis at 350 nm in the presence of F1 leads to inhibition of the ATPase activity. The presence of ATP during illumination prevents the inhibition. Illumination of F1 in the absence of 8-azido-ATP causes no inhibition. 3. Added Mg2+ is not necessary for the binding of the 8-azido-ATP to F1. 4. 8-Azido-ATP binds specifically to the beta subunits of F1. 5. The ATPase activity is completely inhibited when 2 mol of 8-azido-ATP are bound per mol F1.
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PMID:Specific photolabelling of beef-heart mitochondrial ATPase by 8-azido-ATP. 13 19

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. Preincubation of MgATP submitochondrial particles with EDTA or Tris.HCl liberated a measurable amount of ATPase inhibitor that could be rapidly purified using only trichloroacetic acid precipitation and heat treatment. 2. In spite of the emergence of high ATPase activity, a considerable amount of ATPase inhibitor was left in the particles. Comparative analysis of other submitochondrial preparations indicated that only AS-particles were effectively depleted. 3. The high ATPase activity of inhibitor-deficient particles, was labile at low temperature provided that the exposure to cold was done in the presence of MgATP. Other nucleotides could not substitute for ATP. Glycerol inhibited and salts enhanced the cold inactivation of membrane-bound F1-ATPase. Isolation of F1-ATPase from cold-inactivated particles yielded a soluble preparation of correspondingly lower activity. 4. It is concluded that together with the increase of ATPase activity, the ATP-dependent cold lability of membrane-bound F1-ATPase and the dislocation of ATPase inhibitor at non operative sites reveal the extent of ATPase complex disorganization.
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PMID:Cold lability of membrane-bound F1-ATPase. 14 42

1. Beef-heart mitochondrial ATPase (F1) is inactivated and dissociated by incubation with 0.85 M LiCl. ATP partly protects against inactivation. Three dissociation products could be identified after chromatography on diethylaminoethylcellulose: the delta subunit which is not adsorbed, the beta subunit which may be eluted from the column, and the alpha and gamma subunits which remain bound to the column. 2. Aurovertin binds to dissociated F1 with a fluorescence enhancement equal to about 30% that found with F1. Unlike intact F1 which shows two kinetically separated phases of fluorescence enhancement, only a fast phase is found with dissociated enzyme. 3. Fluorescence measurements at varying aurovertin and protein concentrations indicate that aurovertin binds to dissociated F1 in a simple 3-component reaction with dissociation constant 0.4 muM. There are two indistinguishable binding sites, calculated on the basis of the initial F1 concentration before dissociation. 4. The beta subunit was isolated from dissociated F1 by DEAE-cellulose chromatography. It has no ATPase activity but reacts with aurovertin with a fluorescence enhancement similar to that of dissociated F1. 5. The isolated beta subunit contains one aurovertin binding site with a dissociation constant of 0.56 muM. 6. It is concluded that F1 contains two beta subunits.
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PMID:The binding of aurovertin to isolated beta subunit of F1 (mitochondrial ATPase). Stoicheiometry of beta subunit in F1. 14 45


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