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)

The proton circuit devised by Mitchell in the chemiosmotic theory was subjected to analysis using the formalism of irreversible thermodynamics. The phenomenological coefficients and the degree of coupling relating co-permeant flows were derived from anion/H+, substrate/H+, cation/H+ and anion/anion biporter models. Linearity and equality of the cross-coefficients in Onsager relations were always satisfied. Macroscopic flows leading to charges splitting, such as oxido-reduction, hydro-dehydratation and transhydrogenase, are driven by a composite thermodynamic force which includes the proton-motive component. Multiple coupling occurs in the circuit when it is assumed that the net inward flux of protons becomes zero, i.e. when the circulation of protons reaches a stationary state. Under these conditions, oxidative phosphorylation, ATPase- or respiration-linked transhydrogenase and uptake of anion or cation against their electrochemical gradient may be predicted, in agreement with known experimental evidence.
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PMID:A non-equilibrium thermodynamics analysis of active transport within the framework of the chemiosotic theory. 0 23

1. Tributyltin at concentrations of approx. 1nmol/mg of protein induces respiratory control and lessens the protein permeability of coupling-factor-deficient submitochondrial particles. 2. At these concentrations or lower, it increases the P/O ratio of the particles to a small extent and inhibits the adenosine triphosphatase activity without greatly increasing its sensitivity to uncoupling agents. 3. It fails to stimulate ATP-driven reversed electron transport or transhydrogenase, but stimulates the transhydrogenase driven by aerobic succinate oxidation. 4. The results indicate that, unlike oligomycin, tributyltin does not discriminate between damaged and intact ATP-synthesizing complexes. 5. The relationship between the oligomycin- and tributyltin-binding sites is discussed.
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PMID:The action of tributyltin on energy coupling in coupling-factor-deficient submitochondrial particles. 0 63

The purpose of this work was in investigate the capability of cell extracts of Escherichia coli and E. coli treated with colicin K to catalyze the following energy-dependent reverse transhydrogenase reaction: NADP + NADH + ATP in equilibrium NADPH + NAD +ADP + Pi. Under anaerobic conditions this reaction requires the presence of a specific portion of the electron transport chain, a functional energy coupling system, including an adenosine triphosphatase, enzyme, and ATP as energy source. The ATP-linked reaction was partially inhibited in French press extracts of E. coli K-12 C600 cells that had been pretreated with colicin K but not in extracts from similarly treated cells of a colicin-tolerant mutant. Ultracentrifugation of extracts yielded particulate fractions competent in catalyzing the reaction; this reaction is substantially inhibited in fractions from colicin-treated cells. The extent of inhibition increased with increasing concentration of colicin. Supernatants also supported ATP-linked formation of NADPH, but this reaction was insensitive to the colicin effect. A comparison between the requirement of the reaction in supernatant and particulate fractions suggests that the reaction in the supernatant is different from the one inhibited by colicin. The ATP-hydrolyzing ability of particulate fractions from the control or treated bacteria was identical. Likewise, the electron transport chain was not affected by colicin treatment, as evidenced from lack of effect on NADH oxidase, succinic dehydrogenase, and NADPH-NAD transhydrogenase. It is concluded that colicin K interferes with the coupling of ATP the utilization of the intermediate for the ATP-linked transdehydrogenase reaction.
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PMID:Effect of colicin K on a membrane-associated, energy-linked function. 0 29

1. ATPase isolated from Rhodospirillum rubrum by chloroform extraction and purified by gel filtration or affinity chromatography shows three bands (alpha, beta and gamma) upon electrophoresis in sodium dodecyl sulphate. 2. Ca2+-ATPase activity of the preparation is inhibited by aurovertin and efrapeptin but not by oligomycin. Activity may be inhibited by treatment with 4-chloro-7-nitrobenzofurazan and subsequently restored by dithiothreitol. 3. The enzyme fails to reconstitute photophosphorylation in chromatophores depleted of ATPase by sonic irradiation. 4. Most of the active protein from the crude chloroform extract binds to an affinity chromatography column bearing an immobilised ADP analogue but not to a column bearing immobilised pyrophosphate. 5. In the absence of divalent cations, a component with a very high specific activity for Ca2+-ATPase is eluted from the column by 1.6 mM ATP. This protein migrates asa single band on 5% polyacrylamide gel electrophoresis and only possesses three subunits. At 12 mM ATP an inactive protein is eluted which does not run on acid or alkali polyacrylamide gels and shows a complex subunit structure. 6. ATPase preparations prepared by acetone extraction or by sonic irradiation of chromatophores may also be purified 10-fold by affinity chromatography. 7. The inclusion of 5 mM MgCl2 or CaCl2 during affinity chromatography of chloroform ATPase increases the capacity of the column for the enzyme and demands a higher eluting concentration of ATP. 8. When the enzyme is more than 90% inhibited by efrapeptin or 4-chloro-7-nitrobenzofurazan, the binding characteristics of the enzyme are not affected. 9. 10 mM Na2SO3, which greatly stimulates the Ca2+- and Mg2+-dependent ATPase activity of the enzyme and increases Ki (ADP) for Ca2+-ATPase from 50 to 850 micron, prevents binding to the affinity column. Binding may be restored by the addition of divalent cations. 10. Na2SO3 increases the rate of ATP hydrolysis, ATP-driven H+ translocation and ATP-driven transhydrogenase in chromatophores. 11. It is proposed that anions such as sulphite convert the chromatophore ATPase into a form which is a more efficient energy transducer.
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PMID:Affinity chromatography of H+-translocating adenosine triphosphatase isolated by chloroform extraction of Rhodospirillum rubrum chromatophores. Modification of binding affinity by divalent cations and activating anions. 2 12

NAD+ reduction catalyzed by transhydrogenase (EC 1.6.1.1) from E. coli membrane particles at the expense of NADPH oxidation is coupled with phenyldicarbaundecaborate (PCB-) absorption by the particles. This process is inhibited by oxidative phosphorylation protonophorous uncouplers and by equilibration of concentrations of the substrates and products of the transhydrogenase reaction. Elimination of the water-soluble part of membrane ATPase results in the inhibition of PCB- absorption at the expense of the transhydrogenase reaction energy. Treatment of the particles by dicyclohexyl carbodiimide increases the transhydrogenase-coupled absorption of PCB-. The transhydrogenase-induced increase of pPCB in the suspension of particles is directly correlated with the ratio of ([NADPH].[NAD+])/([NADP+].[NADH]). When this value is equal to 1, no energy-dependent increase of pPCB was observed. NADP+ reduction at the expense of NADH oxidation leads to a decrease in the amount of PCB- absorbed by the particles at the expense of ATP hydrolysis energy. The experimental data suggest that NADPH oxidation in the course of the transhydrogenase reaction is coupled with the formation of a membrane potential with a positive charge localized inside the particles.
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PMID:[Transhydrogenase as an additional site of energy accumulation in the E. coli respiratory chain]. 3 31

We have partially purified active delta and epsilon subunits of the E. coli membrane-bound Mg2+-ATPase (ECF1). Treating purified ECF1 with 50% pyridine precipitates the major subunits (alpha, beta, and gamma) of the enzyme, but the two minor subunits (delta and epsilon), which are present in relatively small amounts, remain in solution. The delta and epsilon subunits were then resolved from one another by anion exchange chromatography. The partially purified epsilon strongly inhibits the hydrolytic activity of ECF1. The epsilon fraction inhibits both the highly purified five-subunit ATPase and the enzyme deficient in the delta subunit. The latter result indicates that the delta subunit is not required for inhibition by epsilon. By contrast, two-subunit enzyme, consisting chiefly of the alpha and beta subunits, was insensitive to the ATPase inhibitor, suggesting that the gamma subunit may be required for inhibition by epsilon. The partially purified delta subunit restored the capacity of ATPase deficient in delta to recombine with ATPase-depleted membranes and to reconstitute ATP-dependent transhydrogenase. Previously we reported (Biochem, Biophys. Res. Commun. 62:764 [1975]) that a fraction containing both the delta and epsilon subunits of ECF1 restored the capacity of ATPase missing delta to recombine with depleted membranes and to function as a coupling factor in oxidative phosphorylation and for the energized transhydrogenase. These reconstitution experiments using isolated subunits provide rather substantial evidence that the delta subunit is essential for attaching the ATPase to the membrane and that the epsilon subunit has a regulatory function as an inhibitor of the ATPase activity of ECF1.
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PMID:Partial purification of active delta and epsilon subunits of the membrane ATPase from escherichia coli. 12 87

Recent genetic analyses of the membrane components involved in energy transduction in Escherichia coli have concentrated on the (Ca2+, Mg2+)-ATPase complex (EC 3.6.1.3). Many mutants have been described with altered biochemical properties and defects in energy-requiring processes such as oxidative phosphorylation, transhydrogenase activity, and active transport of several solutes. This report describes the isolation of a mutant strain of E. coli that is defective in several energy-requiring processes. The strain BG-31 was obtained by "localized mutagenesis" using phage P1c1. The mutation maps at approximately 73.5 min on the E. coli chromosome. Reversion and suppression analyses indicate that the defect is the result of a single amber mutation. This strain is unable to utilize succinate, D-lactate, or malate for growth. Mutant cells are unable to couple the energy derived from the hydrolysis of ATP to the active transport of proline, although coupling of energy derived from electron transport to solute transport appears normal when examined in both cells and isolated membrane vesicles. Isolated membranes of the mutant are unable to couple the energy derived from the hydrolysis of ATP to transhydrogenase activity while they can utilize the energy generated from electron transport to drive transhydrogenase activity. Extracts of strain BG-31 have normal levels of (Ca2+, Mg2+)-ATPase activity. The ATPase portion of the complex, bacterial F1 (BF1), is poorly attached to the membrane portion of the complex. In vitro reconstitution of transhydrogenase activity with stripped membrane fractions and crude preparations of BF1 localize the defect in strain BG-31 to the membrane portion of the complex. Analysis of membranes of the strain BG-31 by acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate demonstrate the absence of a single polypeptide of molecular weight about 54,000 and the appearance of a new polypeptide of lower molecular weight, about 25,000. Analysis of a spontaneous revertant of BG-31 shows complete restoration of the parental phenotype including the gel patterns. The characterization of this mutant provides the first demonstration of the consequences of a structural gene mutation on a polypeptide in the membrane portion of the complex and represents the initial stages in what we hope will be the biochemical definition and functional characterization of this important energy-transducing system.
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PMID:Energy transduction in Escherichia coli. Genetic alteration of a membrane polypeptide of the (Ca2+,Mg2+)-ATPase. 12 96

In contrast with wild-type Salmonella typhimurium LT2, strain HfrA did not have ATP-driven energy-dependent transhydrogenase activity, although ATP-dependent quenching of atebrin fluorescence was normal. Respiration-dependent and energy-independent transhydrogenase, and Ca2+-activated ATPase (adenosine triphosphatase) activities were similar in both strains. Purified ATPases from the two strains had similar specific activities, similar subunit polypeptides, and were equally effective in restoring energy-dependent transhydrogenase activities to membrane particles of strain LT2 from which the ATPase had been stripped. The purified ATPases from both strains could restore respiration-dependent but not ATP-dependent transhydrogenation to stripped particles of strain HfrA. Both strains grew aerobically equally well on salts media containing glucose, malate, succinate, citrate, acetate, pyruvate, fumarate, lactate or aspartate as substrates. Growth on glucose under anaerobic conditions was similar. Strains LT2 and HfrA were equally effective in the accumulation under both aerobic and anaerobic conditions of the amino acids proline, phenylalanine, histidine, lysine, isoleucine and aspartic acid. Inhibition of amino acid accumulation by KCN and dicyclohexylcarbodi-imide occurred to the same extent in both strains. The complete inhibition by dicyclohexylcarbodi-imide of amino acid uptake under anaerobic conditions suggested that ATP could drive amino acid uptake in both strains. The ability of strain HfrA to carry out ATP-dependent transport or quenching of atebrin fluorescence but not ATP-dependent transhydrogenation is different from the wild-type strain and from any previously described energy-coupling mutant. It is difficult to reconcile the properties of this mutant with the chemiosmotic hypothesis.
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PMID:Salmonella typhimurium HfrA, a mutant in which adenosine triphosphate can drive amino acid transport but not energy-dependent nicotinamide nucleotide transhydrogenation. 12 57

Oxidative phosphorylation, ATP-32Pi exchange, ATP-dependent quenching of acridine-dye fluorescence, ATP-dependent transhydrogenase and ATP-dependent transport of thiomethyl beta-D-galactoside are shown to be experimentally equivalent tools to study the functional state of the ATPase complex in Escherichia coli wild-type and mutant strains defective in oxidative phosphorylation. According to these criteria ten mutants in the ATPase complex were classified having lesions in the unc A,B region of the chromosome. The first mutant type lacks ATPase activity, but the membrane-integrated part of the complex remains functional (class I). The second mutant type lacks a functional membrane-integrated part, but retains ATPase activity (class II). The third mutant type is shown to be defective in both parts of the ATPase complex (class III).
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PMID:The use of several energy-coupling reactions in characterizing mutants of Escherichia coli K12 defective in oxidative phosphorylation. 13 25

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


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