Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Net synthesis of adenosine 5'-triphosphate (ATP) in energy-depleted cells of Escherichia coli was observed when an inwardly directed protonmotive force was artificially imposed. In wild-type cells, ATP synthesis occurred whether the protonmotive force was dominated by the membrane potential (negative inside) or the pH gradient (alkaline inside). Formation of ATP did not occur unless the protonmotive force exceeded a value of 200 mV. Under these conditions, no ATP synthesis was found when cells were exposed to an inhibitor of the membrane-bound Ca2+- and Mg2+- stimulated adenosine triphosphatase (EC 3.6.1.3), dicyclohexylcarbodiimide, or to a proton conductor, carbonylcyanide-p-trifluoromethoxyphenyl-hydrazone. Adenosine triphosphatase-negative mutants failed to show ATP synthesis in response to either a membrane potential or a pH gradient. ATP synthesis driven by a protonmotive force was observed in a cytochrome-deficient mutant. These observations are consistent with the chemiosmotic hypothesis of Mitchell (1961, 1966, 1974).
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PMID:Protonmotive force as the source of energy for adenosine 5'-triphosphate synthesis in Escherichia coli. 0 27

Growth of Halobacterium halobium under illumination with limiting aeration induces bacteriorhodopsin formation and renders the cells capable of photophosphorylation. Cells depleted of endogenous reserves by a starvation treatment were used to investigate the means by which energy is coupled to the active transport of [14C]proline, -leucine, and -histidine. Proline was readily accumulated by irradiated cells under anaerobiosis even when the photophosphorylation was abolished by the adenosine triphosphatase inhibitor N,N'-dicyclohexylcarbodimiide (DCCD). The uptake of proline in the dark was limited except when the cells were allowed to accumulate adenosine 5'-triphosphate (ATP) by prior light exposure or by the oxidation of glycerol. DCCD inhibited this dark uptake. These findings essentially support Mitchell's chemiosmotic theory of active transport. The driving force is apparently the proton-motive force developed when protons are extruded from irradiated bacteriorhodopsin or by the dydrolysis of ATP by membrane adenosine triphosphatase. Carbonylcyanide m-chlorophenylhydrazone (CCCP), a proton permeant known to abolish membrane potential, was a strong inhibitor of proline uptake. Leucine transport was also apparently driven by proton-motive force, although its kinetic properties differed from the proline system. Histidine transport is apparently not a chemiosmotic system. Dark- or light-exposed cells show comparable initial rats of histidine uptake, and these processes were only partially inhibited by DCCD or CCCP. The histidine system apparently does not utilize ATP per se since comparable rates of uptake were exhibited by cells of differing intracellular ATP levels. Irradiated cells did effect a greater total accumulation of histidine than dark-exposed cells. These findings suggest that ATP is needed for sustained transport.
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PMID:Energy coupling in the active transport of amino acids by bacteriohodopsin-containing cells of Halobacterium holobium. 12 52

Triphenylsulphonium ions inhibit mitochondrial oxidative phosphorylation and adenosine triphosphatase activity. The site of action is on the soluble F1 adenosine triphosphatase component. Triphenylsylphonium ions also inhibit electron transfer in the NAD-cytochrome b region of the respiratory chain. In both types of inhibition, triphenylsulphonium ions are effective at low concentrations, half-maximal inhibition being produced by a concentration of about 20-30 muM. These effects resemble the effects of alkylguanidines on mitochondria and are discussed in relation to the effects of alkylguanidines and other lipophilic cations such as ethidium and dibenzyldimethylammonium ions. A modification of the purification procedure for the soluble mitochondrial adenosine triphosphatase [Beechey, Hubbard, Linnett, Mitchell & Munn (1975) Biochem. J. 148, 533-537] IS DESCRIBED, WHICH YIELDS A PREPARATION WITH A HIGHER SPECIFIC ACTIVITY AND SHOWING FEWER BANDS IN GEL ELECTROPHORESIS.
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PMID:Effects of triphenylsulphonium ions on mitochondria. Inhibition of adenosine triphosphatase activity. 13 79

1. Soluble ATPase (adenosine triphosphatase) activity is released when rat liver submitochondrial particles are shaken with chloroform, provided that ATP or glycerol is present in the suspending medium. The extraction is very rapid and appears to be complete. 2. The ATPase of the chloroform extract is about 50% pure and can be readily purified to a specific activity of 60-70mumol/min per mg of protein by (NH(4))(2)SO(4) fractionation and column chromatography on Sephadex G-200. 3. The particulate and soluble ATPases have many similar properties, including their K(m) values for ATP, activation by various metal ions, hydrolytic activity with other nucleotides and stimulation by bicarbonate ions. 4. Unlike the particulate enzyme, the soluble enzyme is cold-labile and insensitive to oligomycin. 5. The molecular weight indicated by the mobility of the soluble ATPase on Sepharose 6B is 360000. 6. The soluble ATPase combines very readily with liver submitochondrial particles depleted of ATPase by salt extraction, and oligomycin-sensitivity is restored. Very little recombination of the enzyme occurs with chloroform-extracted particles. 7. The soluble enzyme contains orcinol-reactive material, suggesting that it may be a glycoprotein. The carbohydrate content was estimated to be 1-2% by weight. 8. It is concluded that the liver ATPase obtained by the chloroform extraction method of Beechey, Hubbard, Linnett, Mitchell & Munn [(1975) Biochem. J.148, 533-537] is similar to other preparations described previously and that this method is superior in simplicity and speed.
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PMID:Purification and properties of the adenosine triphosphatase released from the liver mitochondrial membrane by chloroform. 15 21

In order to determine the target portion of acetaminophen-induced hepatotoxicity, 750 mg per kg of body weight of acetaminophen was administered to male Wistar strain rats with or without the pretreatment of thiol compounds. In the liver, glutathione content decreased throughout the observation periods, and glutathione S-transferase initially, and later adenosine triphosphatase decreased, followed as elevations of aminotransferases and ornithione carbamoyltransferase in serum. The pretreatment of thiol compounds could not restore hepatic enzyme activities, but partially hepatic glutathione content and serum enzyme elevations. Although distinct time lag existed in biochemical alterations in the liver, hepatic glutathione content was significantly correlated solely with hepatic glutathione S-transferase. The mechanism of acetaminophen hepatotoxicity was discussed from the aspect of biochemical events in cytosol and membrane structure in hepatocytes. The mechanism of acetaminophen induced hepatotoxicity has been extensively investigated, and the hepatotoxicity seems to be related to the toxic metabolites generated by biotransformation process (Gillette et al., 1974, Mitchell et al., 1976). Since the toxic metabolites are conjugated with glutathione (GSH), it is generally accepted that when the hepatocellular GSH content has critically depleted, the metabolites seem to react with hepatocyte macromolecules and/or to produce lipid peroxidation, resulting in biochemical and structural changes leading to cell death (Black, 1980). A hepatotoxic dose of labelled acetaminophen was found throughout the liver and the highest concentration was found in centrilobular area, where considerable disruption and vacuolation of the plasma membrane and of the endoplasmic reticulum also occurred (Jollow et al., 1973, Chiu and Bhakthan, 1978). However remarkably little impairment of several enzyme systems in microsome, such as cytochrome P450 content, arylhydrocarbon hydroxylase and glucuronyl transferase has been reported (Thorgeirsson et al., 1976, Chiu and Bhakthan, 1978: Willson and Hart, 1977, Yamada et al., 1981). To elucidate the exact mechanism of acetaminophen hepatotoxicity, we observed time related biochemical alterations of hepatic GSH content, some marker enzymes in hepatocyte subfractions and serum enzymes. The present results indicated that acetaminophen reduced hepatic GSH content, followed as depletions of glutathione S-transferases (GSTs) and finally adenosine triphosphatase (ATPase), associated with elevations of serum enzymes.
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PMID:The target portion of acetaminophen induced hepatotoxicity in rats: modification by thiol compounds. 666 1