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

In rats treated with single, sublethal doses of p,p'-DDT oxidative phosphorylation efficiency, respiratory activity and "latent" ATPase activity in liver and brain mitochondria were determined. A time- and dose-dependent decrease in oxidative phosphorylation efficiency was found. Time-dependent suppression of respiratory activity in state 3 was noticed and a stimulation of mitochondrial ATPase activity 24 h after DDT treatment in liver and brain mitochondria was found. The correlation between time-dependent changes in the brain mitochondrial fraction and distribution of DDT in brain after a single, oral dose is discussed. It is suggested that changes in mitochondria were caused by DDT and its metabolites. It is concluded that the uncoupling of oxidative phosphorylation especially in brain mitochondria could be responsible for some DDT intoxication symptoms in mammals.
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PMID:The mode of action of p,p'=DDT on mammalian mitochondria. 13 71

1. Modification of a single amino acid residue by introduction of the nitrobenzofurazan group inactivates mitochondrial ATPase (adenosine triphosphatase) when membrane-bound in submitochondrial particles. The similarity between the reactions of both membrane-bound and isolated ATPase with 4-chloro-7-nitrobenzofurazan indicates that the single essential tryosine residue identified in the isolated enzyme [Ferguson, Loyd, Lyons & Radda (1975) Eur. J. Biochem. 54, 117-126] Is also a feature of the membrane-bound ATPase. 2. A procedure is presented for estimating the ATPase content of the inner mitochondrial membrane. It is based on the specificity of the incorporation of the nitrobenzofurazan group, and the ready removal of this group by compounds that contain a thiol group. This method indicates that 8.5% of the membrane protein is ATPase. The procedure should be applicable to the titration of the energy-transducing ATPases of bacterial plasma membranes and of the thylakoid membranes of chloroplasts. 3. Combination of the data obtained on the ATPase content of the bovine heart inner mitochondrial membrane with a titration of the cytochrome bc1 complex with antimycin indicates that these two components of the membrane are present in approximately equal amounts.
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PMID:A method for determining the adenosine triphosphatase content of energy-transducing membranes. reaction of 4-chloro-7-nitrobenzofurazan with the adenosine triphosphatase of bovine heart submitochondrial particles. 13 62

1. Isolated F1 (mitochondrial ATPase) binds to urea-treated submitochondrial particles suspended in sucrose/Tris/EDTA with a dissociation constant of 0.1 muM. 2. About one-third of the F1 and the oligomycin-sensitivity conferring protein (OSCP) are lost during preparation of submitochondrial particles prepared at high pH (A particles). None is lost from particles treated with trypsin (T particles). 3. After further treatment with alkali of urea-treated particles, binding of F1 requires the addition of OSCP. Maximum binding is reached when both OSCP and Fc2 are added. The concentration of F1-binding sites in the presence of both OSCP and Fc2 is about the same as that in TU particles. 4. After further extraction with silicotungstate of urea- and alkali-treated particles, OSCP no longer induces binding of F1, unless Fc2 is also present. Fc2 induces binding in the absence of OSCP but with a lower binding constant and, in contrast to results under all the other conditions studied in this paper, the ATPase activity is oligomycin insensitive. 5. It is tentatively concluded that OSCP is the binding site for F1 and Fc2 is the binding site for OSCP.
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PMID:Proteins required for the binding of mitrochondrial ATPase to the mitochondrial inner membrane. 13 85

A heat-stable protein has been detected in Saccharomyces cerevisiae which inhibits mitochondrial ATPase activity. The protein inhibitor has been isolated from extracts prepared by brief heat treatment of unbroken cell suspensions. The isolated inhibitor is a small basic protein (molecular weight close to 7000, isoelectric proint 9.05) devoid of tryptophan, tyrosine, and cysteine as well as proline. The NHP2-terminal amino acid is serine. The ultraviolet absorption spectrum shows the vibrational fine structure of the phenyl-alanine band. Like the ATPase inhibitor from bovine heart mitochondria the yeast inhibitor is rapidly destroyed by trypsin. It is also inactivated by the yeast proteinases A and B. Radioimmunological analysis indicates that the inhibitor is synthesized on cytoplasmic ribosomes. Its accumulation seems to be connected to the formation of the mitochondrial ATPase complex, since its specific activity is greatly reduced both in extracts obtained from the F1-ATPase-deficient nuclear mutant pet 936 and from the cytoplasmic petite mutant D 273-10B-1.
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PMID:A protein inhibitor of mitochondrial adenosine triphosphatase (F1) from Saccharomyces cerevisiae. 13 3

The nuclear pleiotropic respiratory-deficient mutant pet1 (previously M126) exhibits cytochromes aa3 and b deficiencies accompanied by loss of the oligomycin-sensitivity of the mitochondrial ATPase. The mutant pet1, unable to grow on glycerol, growth on glucose. The latter phenotypic trait symbolized by ANAS-D, exhibits a high frequency (2 to 4 X 10(5)) Of spontaneous suppression into Antimycin A-resistant strains. Mutagenesis with MnCl2 increases by a factor of 10(2) the frequency of ANAR-D derivatives. This suppression is partial since none of the suppressed strains is able to grow on glycerol even when respiratory functions and cytochromes activities are restored as in the pet1 [SUP2] strain. In the latter strain it is concluded that the extralocus suppressor gene [SUP2] is responsible for the ANAR-D trait. Tetrad analysis in a cross homozygous for pet1 demonstrates a non-Mendelian segregation pattern for the SUP2 suppressor gene. In stable diploids, homozygous for pet1, the [SUP2] suppressor exhibits a mitotic segregation pattern. Furthermore the transmission of the [SUP2] gene is decreased by ethidium bromide treatment. Therefore, the [SUP2] suppressor gene responsible for partial suppression of the nuclear pleiotropic phenotype in mutant pet1 is of cytoplasmic heredity.
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PMID:A cytoplasmic gene for partial suppression of a nuclear pleiotropic respiratory deficient mutant in the petite negative yeast Schizosaccharomyces pombe. 13 78

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. 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


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