Electron Spin Polarization Model Applied to Sequential Electron Transfer in Iron-Containing Photosynthetic Bacterial Reaction Centers with Different Quinones as QA

Morris, Andrea L.; Snyder, Seth W.; Zhang, Yuenian; Tang, Jau; Thurnauer, Marion C.; Dutton, P. Leslie; Robertson, Dan E.; Gunner, M. R.

doi:10.1021/j100011a063

Cited by 57 publications

(88 citation statements)

References 12 publications

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“…In the slow sample the high field region of the spectrum shifts toward all enhanced absorption while the low field shifts toward all emission compared to the fast sample. These spectral changes reflect the predicted trends expected from SETP modeling, i.e., for longer lifetimes of P 86/ If, the spectra reflect the transfer of chemically induced electron polarization (CIDEP) Morris et al, 1995) from P86/H-. The SETP model has been used to fit the temperature dependent spectral data.…”

Section: Transfer Dynamics In Bacterial Reaction Center Proteinssupporting

confidence: 71%

“…In the purple photosynthetic bacterial RC protein, the primary radical pair Ps6/lf, where H denotes a monomeric bacteriopheophytin, is formed within -3 ps of photoexcitation of the special pair of bacteriochlorophylls, PS65• Morris et aI., 1990;Morris et al, 1995;Tang et aI., 1996;Hore, 1996;Kandrashkin et aI., 1997). The SETP model includes both secondary and intermediate radical pairs as well as decay rate constants for the singlet, ks, and triplet, kT, sublevel of the P86/11 radical pair, and the electron transfer rate constant, ~, from P86/11 to P86/QA" A simplified scheme of the radical pair states and electron transfer pathways in the bacterial RC proteins is shown in Figure 1.…”

Section: Transfer Dynamics In Bacterial Reaction Center Proteinsmentioning

confidence: 99%

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Time-Resolved High-Frequency and Multifrequency EPR Studies of Spin-Correlated Radical Pairs in Photosynthetic Reaction Center Proteins

Thurnauer

Poluektov

Kothe

2004

Very High Frequency (VHF) ESR/EPR

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Abstract:In this chapter we demonstrate the potential of high-frequency and multifrequency time-resolved electron paramagnetic resonance (EPR) to reveal unique information on the electron-transfer processes in the photosynthetic systems, where spectra exhibit spin-polarization phenomena. A precise determination of the magnetic resonance parameters of the radicals in the spin-correlated radical pairs with highfrequency EPR facilitates an analysis of more sophisticated models and methods, such as sequential electron transfer spin-polarization and quantum beats oscillations. These approaches help to describe dynamics, structure and electron transfer pathways in the photosynthetic proteins. In the first part of the manuscript we concentrate on the study of the dynamics of the sequential electron-transfer in deuterated photosynthetic bacterial reaction center proteins. High-frequency EPR spectroscopy reveals the influence of the relationship between structure and dynamics on the rate of charge separation. In the second part of the chapter we demonstrate how the three-dimensional structure of the electron intermediates in green plant photosystem I can be determined by high time-resolution multifrequency and high-frequency EPR techniques.

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Section: Transfer Dynamics In Bacterial Reaction Center Proteinssupporting

confidence: 71%

Section: Transfer Dynamics In Bacterial Reaction Center Proteinsmentioning

confidence: 99%

Time-Resolved High-Frequency and Multifrequency EPR Studies of Spin-Correlated Radical Pairs in Photosynthetic Reaction Center Proteins

Thurnauer

Poluektov

Kothe

2004

Very High Frequency (VHF) ESR/EPR

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“…By going to the high field the singlet-triplet mixing becomes extremely fast due to the about 14 times stronger Zeeman interaction and the initial state of the P865QA is not pure singlet anymore. In this case the sequential electron transfer polarization (SETP) model [25][26][27][28][29] should be considered, which includes both the primary and secondary radical pairs. Even with a lifetime of several hundred picoseconds, changes in the lineshape of the polarized HFEPR spectra were demonstrated by spectral simulation in the framework of a SETP model [28,29].…”

Section: A Sequential Electron Transfer In Photosynthetic Reaction Cementioning

confidence: 99%

High-frequency EPR approach to the electron spin-polarization effects observed in the photosynthetic reaction centers

et al. 2001

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Time-resolved high-frequency electron paramagnetic resonance (EPR) spectroscopy was applied to study the structure and dynamics of the electron transfer pathways in the photosynthetic RC proteins. When the spin-polarized EPR spectra are recorded at the high field, the singlet-triplet mixing in the radical pairs becomes faster due to the increase of Zeeman interaction, and a sequential electron transfer polarization model, which includes both the primary and secondary radical pairs, should be considered. Application of the sequential electron transfer polarization model for the interpretation of the bacterial RC proteins with a "slow" electron transfer rate reveals the importance of the protein dynamics. It was shown that the reorganization energy for the electron transfer process between P8fi5H-QA and Pfl65HQ^, but not the change in the structure of the donor-acceptor complex, is a dominant factor that alters the electron transfer rate. The relaxation data, obtained in the delay after laser flash experiment, have been used to estimate the magnetic interaction in the weakly coupled radical pair. High-frequency spin-polarized EPR spectra allow the quantitative characterization of isotopically labeled quinone exchange in the PS I reaction center proteins.

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“…Whereas for samples in which Fez+ has been replaced by Zn2+ very detailed structural information can be deduced from the spin-polarized radical pair spectra (see below), the information content of the spectra of Fe2+ containing samples is limited. Morris et al (363) have used the deviation between experimental spectra and simulations assuming a generation of the radical in a pure singlet state to estimate the rate constant of ET from Q-to QA in RC with different quinones as QA. A slow ET to QA should result in singlet-triplet mixing already in the primary radical pair.…”

Section: Secondary Radical Pairmentioning

confidence: 99%

Radicals and Radical Pairs in Photosynthesis

Angerhofer

Bittl

1996

Photochem & Photobiology

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Electron Spin Polarization Model Applied to Sequential Electron Transfer in Iron-Containing Photosynthetic Bacterial Reaction Centers with Different Quinones as QA

Cited by 57 publications

References 12 publications

Time-Resolved High-Frequency and Multifrequency EPR Studies of Spin-Correlated Radical Pairs in Photosynthetic Reaction Center Proteins

Time-Resolved High-Frequency and Multifrequency EPR Studies of Spin-Correlated Radical Pairs in Photosynthetic Reaction Center Proteins

High-frequency EPR approach to the electron spin-polarization effects observed in the photosynthetic reaction centers

Radicals and Radical Pairs in Photosynthesis

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