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)

We have determined the nucleotide sequence of a segment of Saccharomyces mtDNA that contains the structural gene for one of the subunits (the dicyclohexylcarbodiimide-binding protein) of the mitochondrial ATPase complex. The sequence fits the known amino acid sequence of this protein with the exception of one amino acid. Codon usage is biased in favor of A + T-rich codons. On both sides of the gene, the nucleotide sequence contains less than 4% (mol/mol) G + C for at least 180 nucleotides; these A + T sequences show no evidence of internal repetition. The gene and all the A + T-rich sequence preceding the gene are present in a 12S RNA that is the major transcript of this segment of mtDNA. The nature of the sequences responsible for binding ribosomes to mitochondrial mRNA and for termination of RNA synthesis is considered.
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PMID:Nucleotide sequence of the mitochondrial structural gene for subunit 9 of yeast ATPase complex. 15 63

We investigated the kinetics of mitochondrial ATPase in bovine heart mitochondria and submitochondrial particles upon treatment with phospholipase A2, or upon addition of n-butanol to perturb the lipid protein interactions. The changes observed are the following: (1) Lipid removal or perturbation with butanol is accompanied by loss of ATPase activity with decrease of both V and of the KM for ATP. (2) There are changes of activation energy of ATPase activity at temperatures above the discontinuity normally observed for membrane-bound enzymes in mitochondria. In particular, butanol abolishes the discontinuity, and induces a constant activation energy of about 32 kcal/mol in the range 8--37 degrees C. (3) Butanol modifies the pH dependence of ATPase shifting the pH optimum from around 10 to less alkaline values. The optimum for Mg2+ concentrations is increased by the solvent. (4) Treatment with phospholipase A2 results in a removal of oligomycin-sensitive ATPase, whereas butanol addition prevents oligomycin inhibition of ATPase. (5) In beef heart mitochondria, a spin-labelled analog of the inhibitor, dicyclohexyl carbodiimide, did not show any change in environment upon butanol addition, unlike that found in mitochondria from Saccharomyces cerevisiae.
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PMID:Lipid protein interactions in mitochondria. VII. A comparison of the effects of lipid removal and lipid perturbation of the kinetic properties of mitochondrial ATPase. 15 58

The dicyclohexylcarbodiimide-binding protein of Aspergillus nidulans has been identified as the smallest subunit of the mitochondrial ATPase complex, and has a molecular weight of approximately 8000. It is extractable from whole mitochondria and from the purified enzyme in neutral chloroform/methanol, contains 30% polar amino acids, and the N-terminal amino acid has been identified as tyrosine. Using a double-labelling technique in the absence and presence of cycloheximide, followed by immunoprecipitation of the enzyme complex with antiserum against Neuospora crassa F1 ATPase, it has been shown that this subunit is synthesized on cytoplasmic ribosomes.
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PMID:Mitochondrial ATPase complex of Aspergillus nidulans and the dicyclohexylcarbodiimide-binding protein. 15 78

A series of uncouplers and inhibitors of oxidative phosphorylation have been studied with regard to their effect on the hydrolytic activity of the reduced and oxidized forms of isolated or membrane-bound mitochondrial ATPase. Uncouplers (2,4-dinitrophenol, dicoumarol), which are also activators of the hydrolytic activity of ATPase, were more potent activators on the oxidized form of the enzyme. Inhibitors of oxidative phosphorylation (oligomycin, azide and amytal) had a more potent inhibitory effect on the hydrolytic activity of ATPase in its reduced form. Purified F1-ATPase, oligomycin insensitive in the oxidized form of the enzyme, became sensitive to oligomycin in the reduced form. An interpretation of the results suggests the presence of a mechanism that unifies the action of these different compounds on the synthesis and hydrolysis of ATP catalyzed by mitochondrial ATPase.
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PMID:Effect of uncouplers and inhibitors of oxidative phosphorylation on the reduced and oxidized forms of mitochondiral ATPase. 15 7

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

Soluble mitochondrial ATPase from bovine heart (factor F1) loses its activity during ATP hydrolyses. The inactivation is accelerated by moderate pressure, which is generated in an ultracentrifuge cell. The rate of inactivation slows down if the concentration of the substrate (MgATP) is diminished. ATP hydrolysis proceeds at an almost constant rate if the substrate concentration is as low as 0.05 mM. One intersubunit cross-link formed by dimethylsuberimidate per molecule of factor F1, prevents its inactivation during the ATPase reaction both without pressure and in an ultracentrifuge. Sedimentation coefficients measured by the reacting enzyme centrifugation method of both unmodified factor F1 at a low (about 0.05 mM MgATP) substrate concentration and of its dimethylsuberimidate cross-linked form in the presence of 10 mM MgATP, were determined to be s20, w = 12.4 +/- 0.4 S. The value is the same as that obtained by the conventional boundary sedimentation method in the absence of the substrate. This result testifies to the fact that the conformation of reacting factor F1 in solution is similar to that of the enzyme in the absence of the substrate.
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PMID:Investigation of soluble mitochondrial ATPase by the reacting enzyme sedimentation method. 15 27

ATP concentration modulates oxygen exchange catalyzed by purified, soluble mitochondrial ATPase during ATP hydrolysis so that water oxygen incorporation into each Pi formed increases markedly as ATP concentration is lowered. This behavior is readily explained by catalytic cooperativity between subunits of the ATPase. However, other reasonable explanations also need consideration. A new approach for assessing these various explanations is used, based on measurement of the [18O]Pi species formed by hydrolysis of ATP highly labeled with 18O in the gamma-phosphoryl group. The results and other supporting data give what appears to be the most compelling evidence yet attained for alternating site catalytic cooperativity in an enzymic catalysis.
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PMID:Subunit interaction during catalysis. Alternating site cooperativity of mitochondrial adenosine triphosphatase. 15 96

In vasogenic cerebral oedema, there is progressive quantitative and qualitative impairment of mitochondrial ATPase and of Na/K/ATPase. This impairment, which reflects the intracellular component of cerebral oedema, would appear to be related to changes in the phospholipid environment of the cell membrane enzymes. CDP choline, a metabolic phospholipid precursor, is to a certain extent capable of correcting this disturbed activity and at the same time reduce oedema.
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PMID:[Vasogenic cerebral oedema. Changes in membrane ATPases. Correction by a phospholipid precursor (author's transl)]. 15 43

The enzymic activity of Mg2+- or Ca2+-stimulated ATPase from Escherichia coli was inhibited by one of the troponin components, TN-I, and by mitochondrial ATPase inhibitor (F1-inhibitor). The inhibitory ability of component TN-I against Mg2+-stimulated AtPase activity was lost after digestion of component TN-I with trypsin. The Mg2+-stimulated ATPase activity inhibited by component TN-I was completely restored by the addition of another troponin component TN-C.
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PMID:Inhibition of E coli ATPase activity by a troponin component, TN-I, and by mitochondrial ATPase inhibitor. 16 Mar 25

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


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