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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of Clostridium perfringens was inhibited by compounds which dissipate or prevent the formation of electrochemical proton gradients. Membrane vesicles prepared from this organism exhibited Mg2+-dependent adenosine triphosphatase (ATPase) activity sensitive to N,N'-dicyclohexylcarbodiimide. Mg2+-ATPase activity was optimal of 50 degrees C, but no discrete pH optimum was observed. Adenosine triphosphate-dependent quenching of the fluorescence of the weak base quinacrine by everted membrane vesicles suggested that the Mg2+-ATPase is a proton pump capable of generating an electrochemical proton gradient. Adenosine triphosphate-dependent transport of Ca2+ by everted vesicles was sensitive to uncouplers and inhibitors of the Mg2+-ATPase.
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PMID:Properties and function of the proton-translocating adenosine triphosphatase of Clostridium perfringens. 4 Sep 63

A particulate subcellular fraction from Escherichia coli K-12 induced in anaerobic sn-glycerol 3-phosphate (G3P) dehydrogenase and fumarate reductase can catalyze under anaerobic conditions the transfer of hydrogens from G3P to fumarate, with attendant generation of high-energy phosphate. The phsophorylation process is more sensitive than the transhydrogenation process to inhibition by the detergent Triton X-100. The same is true with respect to sensitivity to sodium azide, carbonyl cyanide m-chlorophenylhydrazone and N,N'-dicyclohexylcarbodiimide. Such a preparation derived from cells with beta-galactoside permease can accumulate thiomethyl beta-D-galactoside anaerobically, and the accumulation can be stimulated twofold by adding G3P and fumarate. Mutants lacking the membrane-associated Mg2+-dependent adenosine triphosphatase cannot grow anaerobically on glycerol with fumarate as the hydrogen acceptor, although they can grow aerobically on glycerol alone.
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PMID:Anaerobic energy-yielding reaction associated with transhydrogenation from glycerol 3-phosphate to fumarate by an Escherichia coli system. 12 85

Basal and trypsin-stimulated adenosine triphosphatase activities of Escherichia coli K 12 have been characterized at pH 7.5 in the membrane-bound state and in a soluble form of the enzyme. The saturation curve for Mg2+/ATP = 1/2 was hyperbolic with the membrane-bound enzyme and sigmoidal with the soluble enzyme. Trypsin did not modify the shape of the curves. The kinetic parameters were for the membrane-bound ATPase: apparent Km = 2.5 mM, Vmax (minus trypsin) = 1.6 mumol-min-1-mg protein-1, Vmax (plus trypsin) = 2.44 mumol-min-1-mg protein-1; for the soluble ATPase: [S0.5] = 1.2 mM, Vmax (-trypsin) = 4 mumol-min-1-mg protein-1; Vmax (+ trypsin) = 6.6 mumol-min-1-mg protein-1. Hill plot analysis showed a single slope for the membrane-bound ATPase (n = 0.92) but two slopes were obtained for the soluble enzyme (n = 0.98 and 1.87). It may suggest the existence of an initial positive cooperativity at low substrate concentrations followed by a lack of cooperativity at high ATP concentrations. Excess of free ATP and Mg2+ inhibited the ATPase but excess of Mg/ATP (1/2) did not. Saturation for ATP at constant Mg2+ concentration (4 mM) showed two sites (groups) with different Kms: at low ATP the values were 0.38 and 1.4 mM for the membrane-bound and soluble enzyme; at high ATP concentrations they were 17 and 20 mM, respectively. Mg2+ saturation at constant ATP (8 mM) revealed michealian kinetics for the membrane-bound ATPase and sigmoid one for the protein in soluble state. When the ATPase was assayed in presence of trypsin we obtained higher Km values for Mg2+. These results might suggest that trypsin stimulates E. coli ATPase by acting on some site(s) involved in Mg2+ binding. Adenosine diphosphate and inorganic phosphate (Pi) act as competitive inhibitors of Escherichia coli ATPase. The Ki values for Pi were 1.6 +/- 0.1 mM for the membrane-bound ATPase and 1.3 +/- 0.1 mM for the enzyme in soluble form, the Ki values for ADP being 1.7 mM and 0.75 mM for the membrane-bound and soluble ATPase, respectively. Hill plots of the activity of the soluble enzyme in presence of ADP showed that ADP decreased the interaction coefficient at ATP concentrations below its Km value. Trypsin did not modify the mechanism of inhibition or the inhibition constants. Dicyclohexylcarbodiimide (0.4 mM) inhibited the membrane-bound enzyme by 60-70% but concentrations 100 times higher did not affect the residual activity nor the soluble ATPase. This inhibition was independent of trypsin. Sodium azide (20 muM) inhibited both states of E. coli ATPase by 50%. Concentrations 25-fold higher were required for complete inhibition. Ouabain, atebrin and oligomycin did not affect the bacterial ATPase.
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PMID:Membrane bound and soluble adenosine triphosphatase of Escherichia coli K 12. Kinetic properties of the basal and trypsin-stimulated activities. 12 30

Disrupted cells of Bdellovibrio bacteriovorus exhibited adenosine triphosphatase activity, 60 to 80% of which was in the soluble fraction. Dicyclohexylcarbodiimide did not inhibit the adenosine triphosphatase activity in membrane particles. The particles did not show energy-linked transhydrogenase activity. The activity of non-energy-linked transhydrogenase as well as the rate of oxygen consumption were higher in membrane particles of the host-independent strain than in the host-dependent strains. The uptake of amino acid uptake was inhibited by cyanide and by carbonyl cyanide p-trifluoromethoxyphenyl hydrazone. Valinomycin, in the presence of K+, did not inhibit the uptake, and only partial inhibition was exerted by arsenate and dicyclohexylarbodiimide. Sulfhydryl reagents inhibited amino acid uptake.
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PMID:Membrane-associated, energy-linked reactions in Bdellovibrio bacteriovorus. 13 28

The adenosine 5'-triphosphate (ATP)-linked transhydrogenase reaction, present in the particulate fractions of Escherichia coli, was previously shown to be inhibited in these fractions when the bacteria were treated with colicins K or El. The purpose of this study was to characterized the ATP-linked transhydrogenase reaction and the colicin-caused inhibition of the reaction in purified cytoplasmic membranes. Particulate fractions from bacteria treated or untreated with colicins were separated on sucrose gradients into cell wall membrane and cytoplasmic membrane fractions. The ATP-linked transhydrogenase reaction was found to be exclusively associated with the cytoplasmic membrane fractions. The reaction was inhibited by carbonylcyanide m-chlorophenlhdrazone, dinitrophenol, N,N'-dicyclohexylcarbodiimide, and trypsin. Although the cytoplasmic membrane fractions were purified from the majoriy of the cell wall membrane and its bound colicins, they showed the inhibitory effects of colicins K and El on the ATP-linked transhydrogenase reaction. The inhibition of ATP-linked transhydrogenase reaction induced by the colicin could not be reversed by subjection the isolated membranes to a variety of physical and chemical treatments. Cytoplasmic membranes depleted of energy-transducing adenosine triphosphatase ATPase) complex (coupling factor) lost the ATP-linked transhydrogenase activity. The ATPase complexes isolated from membranes of bacteria treated or untreated with colicins El or K reconstituted high levels of ATP-linded transhydrogenase activity to depleted membranes of untreated bacteria. The same ATPase complexes reconstituted low levels of activity to depleted membranes of the treated bacteria.
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PMID:Adenosine 5'-triphosphate-linked transhydrogenase in cytoplasmic membranes of colicin-treated and untreated Escherichia coli. 13 1

Colicin K greatly decreased the incorporation of 32P-labeled inorganic orthophosphate into nucleotides and nucleic acids, causing a concomitant increase in the formation of 32P-labeled sugar phosphates in sensitive cells of Escherichia coli. These sugar phosphates were formed in aerobically growing cells, as well as in cells under stringent control of ribonucleic acid synthesis. The main 32P-labeled product was identified as sedoheptulose 7-phosphate in two strains (B1 and K-12 MK-1) and fructose 1,6-diphosphate in one strain (K-12 CP78). The formation of sugar phosphates induced by colicin K was inhibited by carbonyl cyanide m-chlorophenylhydrazone. It was also not observed in N,N'-dicyclohexylcarbodiimide-treated cells or Mg2+-(Ca2+)-adenosine triphosphatase-less mutant (strain K-12 AN120) cells. Thus, the formation of sugar phosphates in colicin K-treated cells is dependent on the formation of adenosine 5'-triphosphate by oxidative phosphorylation.
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PMID:Formation of sugar phosphates in colicin K-treated Escherichia coli. 14 46

The transduction of energy through biological membranes was investigated in Escherichia coli strains defective in the ATP synthetase complex. Everted vesicles prepared from strains containing an uncA or uncB mutation were compared with those of the parental strain for their ability to couple energy derived from the oxidation of substrates by the electron transport chain or from the hydrolysis of ATP by the Mg2+-adenosine triphosphatase, as measured by the energy-dependent quenching of quinacrine fluorescence or the active transport of 45Ca2+. Removal of the Mg2+-adenosine triphosphatase from membranes derived from the parental or an uncA strain caused a loss of energy-linked functions and a concomitant increase in the permeability of the membrane for protons. Proton impermeability was restored by treatment with N,N'-dicyclohexylcarbodiimide. When membranes of the uncB strain were treated in a similar manner, there was no loss of respiratory-driven functions, nor was there a change in proton permeability. These observations suggest that the uncB mutation specifically results in alteration of an intrinsic membrane protein channel necessary for the generation of utilzation of the electrochemical gradient of protons by that complex. Loss of the function of the proton channel is believed to prevent the transduction of energy through the ATP synthetase complex.
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PMID:Energy transduction in Escherichia coli: physiological and biochemical effects of mutation in the uncB locus. 14 32

The inhibition of the membrane-bound adenosine triphosphatase of Escherichia coli by DCCD (dicyclohexylcarbodi-imide) is studied under conditions of varying KCl concentration. An increase in K+ concentration and in other cations causes an increase in the DCCD sensitivity of the enzyme, as well as significant changes in the kinetic parameters.
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PMID:Inhibition of the membrane-bound adenosine triphosphatase of Escherichia coli by dicyclohexylcarbodi-imide. 14 61

The oligomycin- and N,N'-dicyclohexylcarbodiimide-sensitive adenosine triphosphatase complex extracted with Triton X-100 from the chromatophores of Rhodospirillum rubrum was extensively purified. The purification procedure included (diethylamino)ethylcellulose chromatography and glycerol gradient centrifugation. The specific activity of Mg2+-dependent ATP hydrolysis in the purified preparation increased about 11-fold, while that of Ca2+-dependent ATP hydrolysis increased 50-fold as compared with chromatophores. The purified adenosine triphosphatase complex dissociated into a maximum of eight different polypeptides upon electrophoresis in the presence of sodium dodecyl sulfate. The estimated subunit molecular weights were as follows: 56 000 (alpha), 50 000 (beta), 33 000 (gamma), and those ranging from 17 000 to 9400 for the remaining smaller subunits. The purified preparation was incorporated into phospholipid vesicles by using the freeze--thaw technique. The reconstituted vesicles catalyzed [32P]ATP exchange, which was almost completely inhibited by both oligomycin and N,N'-dicyclohexylcarbodiimide as well as by a protonophorous uncoupler, carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone.
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PMID:Purification of the energy-transducing adenosine triphosphatase complex from Rhodospirillum rubrum. 15 74

Hydrogenase and the adenosine 5'-triphosphate (ATP) synthetase complex, two enzymes essential in ATP generation in Methanobacterium thermoautotrophicum, were localized in internal membrane systems as shown by cytochemical techniques. Membrane vesicles from this organism possessed hydrogenase and adenosine triphosphatase (ATPase) activity and synthesized ATP driven by hydrogen oxidation or a potassium gradient. ATP synthesis depended on anaerobic conditions and could be inhibited in membrane vesicles by uncouplers, nigericin, or the ATPase inhibitor N,N'-dicyclohexylcarbodiimide. The presence of an adenosine 5'-diphosphate-ATP translocase was postulated. With fluorescent dyes, a membrane potential and pH gradient were demonstrated.
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PMID:Chemiosmotic coupling in Methanobacterium thermoautotrophicum: hydrogen-dependent adenosine 5'-triphosphate synthesis by subcellular particles. 16 Apr 8


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