Initial formation of ATP in photophosphorylation does not require a proton gradient

Vinkler, Chana; Avron, Mordhay; Boyer, Paul D.

doi:10.1016/0014-5793(78)81077-1

Cited by 43 publications

(25 citation statements)

References 21 publications

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“…Contrary to an often expressed statement [25,26] the onset of phosphorylation does not only depend on the transmembrane electric potential difference. It must be recalled that chloroplasts, even in the dark, can present a significant ApH across the membrane.…”

Section: Sensitivity Of a Tp Synthesis To Uncouplerscontrasting

confidence: 69%

“…In such conditions nigericin in the presence of K + should not inhibit ATP synthesis. The results in [25,26] supported this prediction at least at external pH 7. On the contrary, at external pH 7 or 8, very low concentrations of nigericin inhibited flash-induced phosphorylation in our chloroplasts.…”

Section: Sensitivity Of a Tp Synthesis To Uncouplerssupporting

confidence: 68%

“…It has been thought that in flashing light or in the initial period of illumination photophosphorylation only depends on the transmembrane electric potential [25,26]. In such conditions nigericin in the presence of K + should not inhibit ATP synthesis.…”

Section: Sensitivity Of a Tp Synthesis To Uncouplersmentioning

confidence: 99%

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Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Galmiche¹,

Girault²

1982

FEBS Letters

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Section: Sensitivity Of a Tp Synthesis To Uncouplerscontrasting

confidence: 69%

Section: Sensitivity Of a Tp Synthesis To Uncouplerssupporting

confidence: 68%

See 1 more Smart Citation

Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Galmiche¹,

Girault²

1982

FEBS Letters

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“…However, the question of whether the proton pathway is delocalized throughout the bulk aqueous volume or is localized at its membrane surface has remained open to discussion since it was first raised in 1961 by Williams [9][10][11][12][13]. He [14] rightly pointed out the deficiency of the Mitchellian delocalized proton-coupling view by stating: "If charge is thrown out into the medium, as in osmotic theories, then we face the problem of equilibration of the energy of single cell on its outside with the whole of the volume in which it is suspended, say the Pacific Ocean.…”

Section: Introductionmentioning

confidence: 99%

Experimental Demonstration of Localized Excess Protons at a WaterMembrane Interface

Saeed¹,

Lee²

2015

Bioenergetics

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The widespread Mitchellian proton motive force equation has recently been revised with the proton-electrostatics localization hypothesis, which, for the first time, successfully elucidates the 30-year longstanding energetic conundrum of ATP synthesis in alkalophilic bacteria. To demonstrate the fundamental behavior of localized protons in a pure watermembrane-water system in relation to the newly derived pmf equation, excess protons and excess hydroxyl anions were generated by utilizing an "open-circuit" water-electrolysis system and their distributions were tested using a protonsensing aluminum membrane. The proton-sensing film placed at the membrane-water interface displayed dramatic localized proton activity while that placed into the bulk water phase showed no excess proton activity during the entire experiment. These observations clearly match with the prediction from the proton-electrostatics localization hypothesis that excess protons do not stay in water bulk phase; they localize at the water-membrane interface in a manner similar to the behavior of excess electrons in a conductor. This finding has significance not only in the science of bioenergetics but also in the fundamental understanding for the importance of water to life in serving as a proton conductor for energy transduction in living organisms.

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“…In chloroplasts [I 1,291 the lag phase preceeding initiation of phosphorylation after illumination is not prolonged by permeant buffers when ApH is the driving force (cf. however [30]). In submitochondrial particles 50 inhibition of the respiration with malonate is accompanied by 500/, depression of J A T~ with no change of A,& [31].…”

mentioning

confidence: 98%

On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria

Zoratti

Pietrobon

Azzone

1982

European Journal of Biochemistry

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The relationship between rate of ATP synthesis, JATp, and value of the proton electrochemical gradient, A f i~ has been analyzed in intact mitochondria.Onset of phosphorylation causes a depression of AfiH of 1.5 kJ/mol. There is a close parallelism between inhibition of &rp and restoration of A i H to its state-4 value during titrations with oligomycin or atractyloside.Titrations The consistence of the present data with either a chemiosmotic model where AFH is the sole and obligatory intermediate for energy coupling, or models where there is a direct transfer of energy between the two pumps is discussed.In mitochondria, bacteria and chloroplasts, e-transfer and ATP hydrolysis occur through the operation of H + pumps, which create a H + electrochemical gradient, A~H , between outer medium and inner space [l]. ATP synthesis is generally thought to occur through a back-to-back coupling of the two H i pumps. The mechanism proposed by Mitchell [2,3], known as the chemiosmotic hypothesis, assumes that coupling between redox and ATP-driven H + pumps is achieved through a delocalized A,& between the bulk aqueous phases and involves a H'-catalyzed reaction at the active site of the ATPase.Other views, although recognizing the fundamental role of protons, differ principally with respect to the molecular mechanisms and to the role of bulk phase A j H . According to Williams [4] the protons are generated in membrane-controlled spaces, not in equilibrium with one another, and the energized protons are trapped locally to drive ATP synthesis. AfiH represents an energy storage rather than an intermediate in coupling [4,5]. In the hypothesis called 'localized chemiosmosis' [6], domains are assumed where H + ions do not freely equilibrate with the bulk phase and where a A,CH higher than in bulk phase is established (cf. also [5,7,28]). Conformational changes of the ATPase are required, in the alternating site model of Boyer [9], for the utilization of A&. However it is doubtful whether these changes are due to the establishment of A f i~ or to protein-protein interactions in the membrane. AfiH-independent mechanisms have also been proposed by others (e.g. [lo-121).ATP synthesis can be driven by an artificial bulk-phase AfiH gradient in mitochondria, submitochondrial particles, Abbreviutions. CF30PhzC(CN)2, carbonylcyanide p-fluoromethoxyphenylhydrazone; Ph3MeP+, triphenylmethylphosphonium; Mops, 4-morpholinepropanesulfonic acid: Ap5A, adenosine(5')pentaphospho-(5')adenosine; J,, electron flow; Ah, electron flow in static head (state 4).chloroplasts and liposomes inlaid with the ATPase sythase complex [13-171. This is compatible with the views that ATP synthesis may be due either exclusively to a H + current through a protonic pathway reaching the FI-active site or to AiH-induced conformational changes coordinated with H + translocation at different sites.If the bulk-phase A& is the sole intermediate coupling the two H + pumps, some quantitative relationship between the rate of ATP synthesis, JATp, and A& is expected. One predicti...

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Initial formation of ATP in photophosphorylation does not require a proton gradient

Cited by 43 publications

References 21 publications

Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Experimental Demonstration of Localized Excess Protons at a WaterMembrane Interface

On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria

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Initial formation of ATP in photophosphorylation does not require a proton gradient

Cited by 43 publications

References 21 publications

Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Synthesis of ATP induced in pea chloroplasts by single turnover flashes

Experimental Demonstration of Localized Excess Protons at a WaterMembrane Interface

On the Relationship between Rate of ATP Synthesis and H+ Electrochemical Gradient in Rat‐Liver Mitochondria

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Product

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On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria