Artificial energy conservation in the respiratory chain. No native coupling site between cytochrome <i>c</i> and oxygen

Hauska, Günter; Trebst, Achim

doi:10.1016/0014-5793(77)80994-0

Cited by 23 publications

(16 citation statements)

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“…Charge separation in the photosystem-I reaction center across the membrane should lead to the formation of a proton gradient if an appropriate redox carrier like plienazine methosulfate is included. Phenazine methosulfate has been shown in chloroplasts to provide an artificial coupling site for ATP synthesis by cyclic electron flow around photosystem-I coupled to proton translocation into the thylakoid, releasing a proton inside upon oxidation, and taking up a proton from the outside upon reduction [3,5]. The fluorescence quenching of aminoacridine was taken as indication for light-induced formation of a proton gradient [22], although the quantitative relationship between the fluorescence quenching and A pH has been questioned by Fiolet et al [23].…”

Section: Reconstitution and Test With Aminoacridinementioning

confidence: 99%

“…The sensitivity of the fluorescence quenching to NH4Cl in the presence and absence of valinomycin is shown in Fig.3. The synergistic effect of valinomycin can be explained by the assumption that in its presence less NH; has to accumulate inside the vesicles for efficient H+-transport in a dissipative NH3-uptake/NH:-release cycle (see [3]). Indirect evidence for the formation of a membrane potential upon illumination of the reaction-center liposomes can be derived from the effect of valinomycin/K+ on the fluorescence quenching.…”

Section: Reconstitution and Test With Aminoacridinementioning

confidence: 99%

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Reconstitution of Photosynthetic Energy Conservation

Orlich

Hauska

1980

European Journal of Biochemistry

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A preparation of reaction centers of photosystem I from spinach chloroplasts was incorporated into lipid vesicles by sonication. Incorporation was tested by chromatography on Sepharose-.IB, by comparison of the elution profiles of photosystem-I reaction center liposomes and of free reaction centers. In the presence of reduced N-methylphenazonium methosulfate the reaction center liposomes catalyzed net proton extrusion in the light, but at the same time showed light-induced quenching of 9-aminoacridine fluorescence, with similar extent and kinetics as known for chloroplasts. We conclude that we are dealing with two vesicle populations, one right side-out and one inside-out with respect to the orientation of the incorporated reaction center complex. Net proton movements are influenced by the nature of the cations present in the suspending medium, and the possibilities for effects of surface charge on these movements are discussed. During photosynthetic energy conservation in plants and bacteria light energy is primarily converted into a membrane potential by charge separation in the reaction centers followed by vectorial electron transport within asymmetrically organized membranes. The electron transport is coupled to transmembrane proton translocation, which leads to the formation of an electrochemical potential difference of protons. According to the chemiosmotic theory, this potential difference is the driving force for ATP synthesis [l -41. Therefore the minimal requirements for the reconstitution of photophosphorylation from chloroplast components in a liposomal model system might be: a reaction center chlorophyll-protein complex for the light-induced charge separation, positive inside the vesicle, an appropriate redox system for the formation of a transmembrane proton gradient, acidic also inside, and the coupling factor complex as the enzyme of ATP synthesis, accessible for substrates. Such a comparatively simple electron transport system is probably functioning in chloroplasts in the presence of reduced phenazine methosulfate, if electron flow between the two photosystems is inhibited [5].Abbreviations and Trivial Names. Phenazine methosulfate, Nmethylphenazonium methosulfate; aminoacridine, 9-aminoacridine; CF30PhzC(CN)Z, carbonylcyanide p-trifluoromethoxyphenylhydrazone, also known as FCCP; Tricine, N-[2-hydroxy-l,lbis(hydroxymethyl)ethyl]glycine; P700, reaction center chlorophyll of photosystem I.Reaction center complexes of higher plants and bacteria incorporated into phospholipid membranes have been studied before, in relation to structural and functional aspects. Electron microscopy of freezefractured reaction-center liposomes revealed particlecontaining fracture f x e s in contrast to smooth fracture faces of pure liposomes, indicating that the reaction center is embedded in the lipid matrix [6,7,]. Transmembrane arrangement has not been demonstrated so far by electron microscopy. Proteoliposomes [S] and planar membranes [9] inlayed with reaction centers isolated from photosynthetic bacteria have ...

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Section: Reconstitution and Test With Aminoacridinementioning

confidence: 99%

Section: Reconstitution and Test With Aminoacridinementioning

confidence: 99%

Reconstitution of Photosynthetic Energy Conservation

Orlich

Hauska

1980

European Journal of Biochemistry

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“…This complex involves at least the peripheral membrane protein coupling factor CFI being the actual ATPsynthetase and a nonidentified transmembrane component designated HFo [3,4] . From this complex only the coupling factor could be purified to homogeneity.…”

Section: Introductionmentioning

confidence: 99%

Chloroplast coupling factor CF₁ in solution Small‐angle X‐ray scattering and circular dichroism measurements

Süss

Damaschun

et al. 1978

FEBS Letters

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“…It contains two hemes b, one heme c (cytochrome c1, or cytochrome,f), a highpotential Fe-S center [1,4-71, and possibly bound quinone [8 -111. This evolutionary rather conservative structure gains increasing interest, for it might provide the key to unravel the mechanism of electron-transfer-linked proton transport through membranes, involving either quinone loops or protein pumps (see [12,13]). …”

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confidence: 99%

A Cytochrome f/b₆ Complex of Five Polypeptides with Plastoquinol‐Plastocyanin‐Oxidoreductase Activity from Spinach Chloroplasts

Hurt

Hauska

1981

European Journal of Biochemistry

396

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The isolation of a cytochromeflbs complex from spinach chloroplasts, with high yield and purity is reported. The complex consists of five polypeptides with a molecular mass of 34, 33,23.5,20 and 17.5 kDa, and contains one cytochromej; two cytochromes b6 and the Rieske Fe-S center with two non-heme irons. It does not contain plastocyanin and is almost completely devoid of chlorophyll and carotenoids, but lipid and detergent are present. It is lacking cytochrome b-559, although three of the five polypeptides seem to carry heme groups. The preparation has plastoquinol-plastocyanin oxidoreductase activity with plastoquinol-1 and plastoquinol-9, which is sensitive to 2,5-dibromomethylisopropyl-p-benzoquinone, to 2-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenyl ether, to 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole, and to bathophenanthroline. Characteristics of this activity with respect to substrate concentrations, pH, detergent effect and other parameters are described.

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Artificial energy conservation in the respiratory chain. No native coupling site between cytochrome c and oxygen

Cited by 23 publications

References 23 publications

Reconstitution of Photosynthetic Energy Conservation

Reconstitution of Photosynthetic Energy Conservation

Chloroplast coupling factor CF₁ in solution Small‐angle X‐ray scattering and circular dichroism measurements

A Cytochrome f/b₆ Complex of Five Polypeptides with Plastoquinol‐Plastocyanin‐Oxidoreductase Activity from Spinach Chloroplasts

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Artificial energy conservation in the respiratory chain. No native coupling site between cytochrome c and oxygen

Cited by 23 publications

References 23 publications

Reconstitution of Photosynthetic Energy Conservation

Reconstitution of Photosynthetic Energy Conservation

Chloroplast coupling factor CF1 in solution Small‐angle X‐ray scattering and circular dichroism measurements

A Cytochrome f/b6 Complex of Five Polypeptides with Plastoquinol‐Plastocyanin‐Oxidoreductase Activity from Spinach Chloroplasts

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Chloroplast coupling factor CF₁ in solution Small‐angle X‐ray scattering and circular dichroism measurements

A Cytochrome f/b₆ Complex of Five Polypeptides with Plastoquinol‐Plastocyanin‐Oxidoreductase Activity from Spinach Chloroplasts