Pulsed EPR experiments on radical pairs in photosynthesis: Comparison of the donor‐acceptor distances in photosystem I and bacterial reaction centers

Zech, Stephan G.; Lubitz, Wolfgang; Bittl, Robert

doi:10.1002/bbpc.19961001220

Cited by 57 publications

(61 citation statements)

References 14 publications

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“…The distance from the centre of P700 to the centre of this structure is 25 (AE1) A Ê , in excellent agreement with the 25.4 (AE0.3) A Ê determined by EPR (Zech et al, 1996;Dzuba et al, 1997;.…”

Section: Secondary Electron Acceptorsupporting

confidence: 66%

Photosystem I of Synechococcus elongatus at 4 Å resolution: comprehensive structure analysis

Schubert

Klukas

Krauß

et al. 1997

Journal of Molecular Biology

274

295

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Section: Secondary Electron Acceptorsupporting

confidence: 66%

Photosystem I of Synechococcus elongatus at 4 Å resolution: comprehensive structure analysis

Schubert

Klukas

Krauß

et al. 1997

Journal of Molecular Biology

274

295

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“…In both samples, the isotropic exchange coupling is extremely weak, and only an upper limit of J Ͻ 1.0 Ϯ 0.8 T can be given. Using a simple point-dipole model, the measured dipolar coupling constant corresponds to a distance of 25.3 Ϯ 0.3 Å between P700 ϩ and A 1 Ϫ in the rubA mutant, which is the same within error as the distance of 25.4 Ϯ 0.3 Å established between P700 ϩ and A 1 Ϫ in several preparations of wild-type PS I (13,(23)(24)(25). Thus, the absence of the F X cluster does not influence the position and orientation of phylloquinone in the A 1 site.…”

Section: Electron-spin Echo Distance Measurements Of P700mentioning

confidence: 75%

Assembly of Photosystem I

Shen

Antonkine

Est

et al. 2002

Journal of Biological Chemistry

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The rubA gene was insertionally inactivated in Synechococcus sp. PCC 7002, and the properties of photosystem I complexes were characterized spectroscopically. X-band EPR spectroscopy at low temperature shows that the three terminal iron-sulfur clusters, F X , F A , and F B , are missing in whole cells, thylakoids, and photosystem (PS) I complexes of the rubA mutant. The flashinduced decay kinetics of both P700 ؉ in the visible and A 1 ؊ in the near-UV show that charge recombination occurs between P700؉ and A 1 ؊ in both thylakoids and PS I complexes. The spin-polarized EPR signal at room temperature from PS I complexes also indicates that forward electron transfer does not occur beyond A 1 . In agreement, the spin-polarized X-band EPR spectrum of P700 ؉ A 1 ؊ at low temperature shows that an electron cycle between A 1 ؊ and P700 ؉ occurs in a much larger fraction of PS I complexes than in the wild-type, wherein a relatively large fraction of the electrons promoted are irreversibly transferred to [F A /F B ]. The electron spin polarization pattern shows that the orientation of phylloquinone in the PS I complexes is identical to that of the wild type, and out-of-phase, spin-echo modulation spectroscopy shows the same P700 ؉ to A 1 ؊ center-to-center distance in photosystem I complexes of wild type and the rubA mutant. In contrast to the loss of F X , F B , and F A , the Rieske iron-sulfur protein and the non-heme iron in photosystem II are intact. It is proposed that rubredoxin is specifically required for the assembly of the F X iron-sulfur cluster but that F X is not required for the biosynthesis of trimeric P700-A 1 cores. Since the PsaC protein requires the presence of F X for binding, the absence of F A and F B may be an indirect result of the absence of F X .

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“…[85,86] In this case, the echo is observed out-of-phase [87] and the method is therefore termed out-of-phase ESEEM (electron spin echo envelope modulation). It has been demonstrated that the pulse sequence (p/4)-s-(p)-s echo provides optimum signal.…”

Section: Other Experimentsmentioning

confidence: 99%

Determination of the Nanostructure of Polymer Materials by Electron Paramagnetic Resonance Spectroscopy

Jeschke

2002

Macromol. Rapid Commun.

174

164

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Electron paramagnetic resonance (EPR) spectroscopy is one the few methods that can characterize structural features in the range between 0.5 and 5 nm in systems that lack long‐range order. Approaches based on EPR spectroscopy provide good structural contrast even in complex materials, as the sites of interest can be selectively labeled or addressed by suitably functionalized spin probes using well established techniques. This article assesses the EPR experiments available for distance measurements on nanoscales in terms of the accessible distance range, precision, and sensitivity. Recommendations are derived for the proper choice of experiment for a given problem. Both simple and sophisticated methods for data analysis are described and their limitations are evaluated. It is discussed which assumptions must be made to extract a pair correlation function from EPR data. Finally, applications to the study of polymer chain conformation and the structure of ionically functionalized diblock copolymers are highlighted.

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Pulsed EPR experiments on radical pairs in photosynthesis: Comparison of the donor‐acceptor distances in photosystem I and bacterial reaction centers

Cited by 57 publications

References 14 publications

Photosystem I of Synechococcus elongatus at 4 Å resolution: comprehensive structure analysis

Photosystem I of Synechococcus elongatus at 4 Å resolution: comprehensive structure analysis

Assembly of Photosystem I

Determination of the Nanostructure of Polymer Materials by Electron Paramagnetic Resonance Spectroscopy

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