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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diploid human lymphoblastoid cells with altered response to ouabain inhibition of the (Na+ + K+)-dependent ATPase transport system, manifest both in whole cells and in purified plasma membrane vesicles, were selected for their resistance to 0.1 muM ouabain. Ouabain-resistant (OUA(R)) cells with normal growth at 50 times this dose were recovered at a frequency 1 X 10(-6). This frequency was increased 9-fold after exposure to ethyl methane sulphonate but was decreased by the frameshift mutagen ICR-191, under conditions where both increased the frequency of 8-azaguanine-resistant colonies. The ouabain resistance phenotype was stable after 200 population doublings in the absence of ouabain. OUA(R) clones show showed 30-50% of the wild type amount of 3H-ouabain bound per cell, with the same dissociation constant for ouabain, 0.1 muM at 0.5 mM K+, as observed in wild-type cells. Both the initial rate of uptake of 86Rb+ in OUA(R) cells and the (Na+ + K+)-dependent ATPase activity of OUA(R) plasma membranes showed decreased sensitivity to ouabain inhibition. However, growth and transport properties of OUA(R) cells in the absence of ouabain were unchanged compared with wild type cells.
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PMID:Ouabain-resistant human lymphoblastoid lines altered in the (Na+ + K+)-dependent ATPase membrane transport system. 13 8

Cytochromes a, b and c, and their quantitative distribution in the cells, were studied by means of differential spectra in obligate methane oxidizing bacteria, Methylosinus trichosporium with the serine pathway of methane carbon assimilation and Methylomonas agile with the ribulose phosphate pathway of methane carbon assimilation, and different types of topography of intracytoplasmic membranes. The membranes are involved in processes of coupled respiration which was confirmed by cytochemical reactions employed for studying the terminal step of the electron transport chain and Mg2+-stimulated ATPase.
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PMID:[Localization of energy generators in methane oxidizing bacteria]. 18

Cells of Methanohalophilus halophilus swelled when exposed to hypotonic solutions of NaCl at pH 7.0. The swelling of the cells ceased in the presence of Mg2+. Methane formation by non-growing cells was strongly dependent on the NaCl concentration. Among other monovalent and divalent cations only Li+ and Mg2+ could partly substitute for a specific function of sodium ions. The artificial Na+/H+ antiporter, monensin, exerted a strong inhibitory effect on methane formation from methylamine. The membrane-bound Mg(2+)-stimulated ATPase of these cells was enhanced at low (40 mM) NaCl concentration while higher concentrations of this solute were inhibitory. The results obtained show that sodium ions are a prerequisite for optimal methane formation and ATPase activity in these cells. However, both of these processes required different sodium ion concentrations.
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PMID:Mode of sodium ion action on methanogenesis and ATPase of the moderate halophilic methanogenis bacterium Methanohalophilus halophilus. 153 42

The apical membrane of the rabbit corneal endothelium contains a potassium-selective ionic channel. In patch-clamp recordings, the probability of finding the channel in the open state (Po) depends on the presence of either HCO3- or Cl- in the bathing medium. In a methane sulfonate-containing bath, Po is less than 0.05 at all physiologically relevant transmembrane voltages. With 0 mM [HCO3-]o at +60 mV, Po was 0.085 and increased to 0.40 when [HCO3-]o was 15 mM. With 4 mM [Cl-]o at +60 mV, Po was 0.083 and with 150 mM Cl-, Po increased to 0.36. Low Po's are also found when propionate, sulphate, bromide, and nitrate are the primary bath anions. The mechanism of action of the anion-stimulated K+ channel gating is not yet known, but a direct action of pH seems unlikely. The alkalinization of cytoplasm associated with the addition of 10 mM (NH4)2SO4 to the bath and the acidification accompanying its removal do not result in channel activation nor does the use of Nigericin to equilibrate intracellular pH with that of the bath over the pH range of 6.8 to 7.8. Channel gating also is not affected by bathing the internal surface of the patch with cAMP, cGMP, GTP-gamma-s, Mg2+ or ATP. Blockers of Na/H+ exchange, Na(+)-HCO3- cotransport, Na(+)-K+ ATPase and carbonic anhydrase do not block the HCO3- stimulation of Po. Several of the properties of the channel could explain some of the previously reported voltage changes that occur in corneal endothelial cells stimulated by extracellular anions.
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PMID:Potassium channel in rabbit corneal endothelium activated by external anions. 231 91

Methanogenesis from formaldehyde or formaldehyde + H2, as carried out by Methanosarcina barkeri, was strictly dependent on sodium ions whereas methane formation from methanol + H2 or methanol + formaldehyde was Na+-independent. This indicates that the reduction of formaldehyde to the formal redox level of methanol exhibits a Na+ requirement. During methanogenesis from formaldehyde, a delta pNa in the range of -62 mV to -80 mV was generated by means of a primary, electron-transport-driven sodium pump. This could be concluded from the following results obtained on cell suspensions of M. barkeri. 1. The addition of proton conductors or inhibitors of the Na+/H+ antiporter had no effect on sodium extrusion. 2. During methanogenesis from formaldehyde + H2 a delta psi of -60 mV to -70 mV was generated even in the presence of proton conductors. 3. ATPase inhibitors, applied in the presence of proton conductors, had no effect on primary sodium extrusion or generation of a delta psi. Evidence for a Na+-translocating ATPase could not be obtained.
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PMID:Electron-transport-driven sodium extrusion during methanogenesis from formaldehyde and molecular hydrogen by Methanosarcina barkeri. 285 Jan 82

Bis(2-hydroxy-3-tert-butyl-5-methylphenyl)methane (bis-phenol) is the most potent inhibitor of the (Ca2+ + Mg2+)-ATPase of skeletal muscle sarcoplasmic reticulum yet identified. The compound behaves as a reversible, tight-binding inhibitor with apparent Ki = 0.3 microM. Butylated hydroxytoluene, butylated hydroxyanisole, and 4-nonylphenol are also effective inhibitors. These observations are of particular interest in light of the widespread use of such phenolic antioxidants and stabilizers in the food industry and in the manufacture of rubbers and plastics and the ease with which the compounds are extracted into organic solvents.
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PMID:Phenolic antioxidants: potent inhibitors of the (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum. 294 19

Methane formation from acetate by resting cells of Methanosarcina barkeri was accompanied by an increase in the intracellular ATP content from 0.9 to 4.0 nmol/mg of protein. Correspondingly, the proton motive force increased to a steady-state level of -120 mV. The transmembrane pH gradient however, was reversed under these conditions and amounted to +20 mV. The addition of the protonophore 3,5,3',4'-tetrachlorosalicylanilide led to a drastic decrease in the proton motive force and in the intracellular ATP content and to an inhibition of methane formation. The ATPase inhibitor N,N'-dicyclohexylcarbodiimide stopped methanogenesis, and the intracellular ATP content decreased. The proton motive force decreased also under these conditions, indicating that the proton motive force could not be generated from acetate without ATP. The overall process of methane formation from acetate was dependent on the presence of sodium ions; upon addition of acetate to cell suspensions of M. barkeri, a transmembrane Na+ gradient in the range of 4:1 (Na+ out/Na+ in) was established. Possible sites of involvement of the Na+ gradient in the conversion of acetate to methane and carbon dioxide are discussed. Na+ is not involved in the CO dehydrogenase reaction.
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PMID:Bioenergetics of methanogenesis from acetate by Methanosarcina barkeri. 334 22

The reduction of CO2 or any other methanogenic substrate to methane serves the same function as the reduction of oxygen, nitrate or sulfate to more reduced products. These exergonic reactions are coupled to the production of usable energy generated through a charge separation and a protonmotive-force-driven ATPase. For the understanding of how methanogens derive energy from C-1 unit reduction one must study the biochemistry of the chemical reactions involved and how these are coupled to the production of a charge separation and subsequent electron transport phosphorylation. Data on methanogenesis by a variety of organisms indicates ubiquitous use of CH3-S-CoM as the final electron acceptor in the production of methane through the methyl CoM reductase and of 5-deazaflavin as a primary source of reducing equivalents. Three known enzymes serve as catalysts in the production of reduced 5-deazaflavin: hydrogenase, formate dehydrogenase and CO dehydrogenase. All three are potential candidates for proton pumps. In the organisms that must oxidize some of their substrate to obtain electrons for the reduction of another portion of the substrate to methane (e.g., those using formate, methanol or acetate), the latter two enzymes may operate in the oxidizing direction. CO2 is the most frequent substrate for methanogenesis but is the only substrate that obligately requires the presence of H2 and hydrogenase. Growth on methanol requires a B12-containing methanol-CoM methyl transferase and does not necessarily need any other methanogenic enzymes besides the methyl-CoM reductase system when hydrogenase is present. When bacteria grow on methanol alone it is not yet clear if they get their reducing equivalents from a reversal of methanogenic enzymes, thus oxidizing methyl groups to CO2. An alternative (since these and acetate-catabolizing methanogens possess cytochrome b) is electron transport and possible proton pumping via a cytochrome-containing electron transport chain. Several of the actual components of the methanogenic pathway from CO2 have been characterized. Methanofuran is apparently the first carbon-carrying cofactor in the pathway, forming carboxy-methanofuran. Formyl-FAF or formyl-methanopterin (YFC, a very rapidly labelled compound during 14C pulse labeling) has been implicated as an obligate intermediate in methanogenesis, since methanopterin or FAF is an essential component of the carbon dioxide reducing factor in dialyzed extract methanogenesis. FAF also carries the carbon at the methylene and methyl oxidation levels.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The bioenergetics of methanogenesis. 623 47

A gentamicin-resistant mutant of Pseudomonas aeruginosa PAO503 was selected after ethyl methane sulfonate mutagenesis. The strain, P. aeruginosa PAO2401 had increased resistance to all aminoglycosides tested but exhibited no change for other antibiotics. The mutation designated aglA (aminoglycoside resistance) was 50% cotransducible with the 8-min ilvB,C marker on the P. aeruginosa chromosome. It showed a marked reduction in cytochrome c(552) and nitrate reductase (Nar) and a change in terminal oxidase activity. Cytochrome c(552) is a component of the P. aeruginosa Nar. No changes in succinate and reduced nicotinamide adenine dinucleotide dehydrogenases, ubiquinone content, Mg(2+)/Ca(2+) membrane adenosine triphosphatase, and energy coupling of electron transport to adenosine 5'-triphosphate synthesis were detected. Transport of gentamicin and dihydrostreptomycin was impaired in PAO2401, but transport of proline, arginine, glutamine, glucose or the polyamine spermidine was not reduced. Ribosomes of PAO2401, and PAO503 bound dihydrostreptomycin equally well, and cell extracts did not inactivate gentamicin or dihydrostreptomycin. Strain PAO2401 is resistant to gentamicin and dihydrostreptomycin because of impaired transport of these compounds. The transport studies indicate a selective coupling of dihydrostreptomycin and gentamicin transport with terminal electron transport. This conclusion was supported by results from another mutant (PAO417-T2) with increased Nar activity, enhanced dihydrostreptomycin and gentamicin transport and a reduction in resistance to these drugs. These results are discussed in relation to a refined model for aminoglycoside transport and briefly relative to plasmid-mediated aminoglycoside resistance.
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PMID:Aminoglycoside-resistant mutation of Pseudomonas aeruginosa defective in cytochrome c552 and nitrate reductase. 624 53

The effect of N-methylpyridinium-2-aldoxime methane sulphonate (P2S), a drug recommended for prophylactic and therapeutic purposes in organophosphate poisoning, on intestinal (Na-K) ATPase and adenyl cyclase activities, was tested in rats. Intestinal (Na-K) ATPase activity was determined 5 h after intragastric administration of either 0.15 M NaCl or P2S 200 mg/kg body weight. P2S decreased significantly jejunal and colonic (Na-K)ATPase activity, 17.1 +/- 4.8 (S.E.) and 13.5 +/- 3.0, as compared to that in saline-treated rats, 41.5 +/- 3.0 (S.E.) and 25.4 +/- 1.2 mumol Pi/mg protein per h, respectively. Pretreatment with methyl prednisolone did not prevent the decrease in enzyme activity induced by P2S. Mucosal PGE2 and cAMP contents, adenyl cyclase and phosphodiesterase activities, were similar in P2S and saline-treated rats. It is thus suggested that P2S-induced inhibition of intestinal (Na-K)ATPase activity might be among the mechanisms contributing to looseness of the stool frequently observed following P2S administration.
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PMID:Effect of N-methylpyridinium-2-aldoxime methane sulphonate (P2S) on rat intestinal, (Na-K)ATPase and adenyl cyclase activities. 627 51


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