Transient EPR Spectroscopy as Applied to Light-Induced Functional Intermediates Along the Electron Transfer Pathway in Photosystem I

Stehlik, D.

doi:10.1007/978-1-4020-4256-0_23

Cited by 18 publications

(25 citation statements)

References 96 publications

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“…Q -can be calculated as a stationary, weakly coupled radical pair. The calculation of such spectra is described in detail in a recent review (Stehlik 2006). Here, a brief overview is given with emphasis on some recent developments.…”

Section: Quasi Stationary Light-induced Radical Pairsmentioning

confidence: 99%

“…Transient electron paramagnetic resonance (TREPR) spectroscopy is one of the main techniques that is used to study the electron transfer in photosynthesis (Hoff 1984;Stehlik et al 1989;Levanon 1996;Stehlik and Möbius 1997;Möbius 2000;Prisner et al 2001;van der Est 2001;Lubitz et al 2002;Bittl and Weber 2005;Savitsky and Möbius 2006;Stehlik 2006;Kandrashkin and van der Est 2007;Kothe et al 2008). In general, TREPR refers to the method first reported by Kim and Weissman (1976) in which the EPR response to a short laser flash is detected using continuous microwave irradiation at a fixed magnetic field without field modulation.…”

Section: Introductionmentioning

confidence: 99%

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Transient EPR: using spin polarization in sequential radical pairs to study electron transfer in photosynthesis

Est

2009

Photosynth Res

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The light induced electron transfer in photosynthesis generates a series of sequential spin polarized radical pairs, and transient electron paramagnetic resonance (TREPR) is ideally suited to study the lifetimes and physical and electronic structures of these radical pairs. In this article, the basic principles of TREPR are outlined with emphasis on the electron spin polarization (ESP) that develops during the electron transfer process. Examples of the analysis of TREPR data are given to illustrate the information that can be obtained. Recent applications of the technique to study the functionality of reaction centers, light-induced structural changes, and protein-cofactor interactions are reviewed.

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Section: Quasi Stationary Light-induced Radical Pairsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient EPR: using spin polarization in sequential radical pairs to study electron transfer in photosynthesis

Est

2009

Photosynth Res

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“…In general, EPR techniques have been important not only for identifying the cofactors that participate in the initial electron transfer steps but also for determining their geometrical relationships and electronic interactions within the photosynthetic reaction center protein. With the evolution of time-resolved and multi-frequency EPR methods, the full impact of these spectroscopies to reveal dynamic structural details of electron transfer reactions continue to emerge (Stehlik 2006;Thurnauer et al 2006;Kothe et al 2008;Poluektov and Utschig 2008).…”

Section: Introductionmentioning

confidence: 99%

“…The development and comparative advantages of these two different approaches to time-resolved EPR are described in Norris et al (1980), Trifunac et al (1986), Stehlik (2006), and Kothe et al (2008). Several detection modes can be employed that basically break down to the following: (i) acquisition of a series of EPR spectra (as a function of magnetic field) at fixed delay times following the laser pulse; (ii) acquisition of time profiles obtained by monitoring resonances at fixed magnetic fields as a function of time with respect to the laser pulse.…”

Section: Introductionmentioning

confidence: 99%

What you get out of high-time resolution electron paramagnetic resonance: example from photosynthetic bacteria

Kothe

Thurnauer

2009

Photosynth Res

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The primary energy conversion steps of natural photosynthesis proceed via light-induced radical ion pairs as short-lived intermediates. Time-resolved electron paramagnetic resonance (EPR) experiments of photosynthetic reaction centers monitor the key charge separated state between the oxidized primary electron donor and reduced quinone acceptor, e.g., P(+)(865)Q(-)(A) of purple photosynthetic bacteria. The time-resolved EPR spectra of P(+)(865)Q(-)(A) are indicative of a spin-correlated radical pair that is created from the excited singlet state of P(865) in an ultra-fast photochemical reaction. Importantly, the spin-correlated radical pair nature of the charge separated state is a common feature of all photosynthetic reaction centers, which gives rise to several interesting spin phenomena such as quantum oscillations, observed at short delay times after optical excitation. In this review, we describe details of the quantum oscillation phenomenon and present a complete analysis of the data obtained from the charge separated state of purple bacteria, P(+)(865)Q(-)(A). The analysis and simulation of the quantum oscillations yield the three-dimensional structure of P(+)(865)Q(-)(A) in the photosynthetic membrane on a nanosecond time scale after light-induced charge separation. Comparison with crystallographic data reveals that the position of Q(-)(A) is essentially the same as in the X-ray structure. However, the head group of Q(-)(A) has undergone a 60° rotation in the ring plane relative to its orientation in the crystal structure. The results are discussed within the framework of the previously suggested conformational gating mechanism for electron transfer from Q(-)(A) to the secondary quinone acceptor Q(B).

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“…Many spectroscopy techniques, including electron paramagnetic resonance and Fourier transform infrared spectroscopy, as well as other methods that measure changes in optical absorption, have provided a wealth of information regarding the key elements of PSI energy conversion (Stehlik, 2006;Thurnauer et al, 2006;Breton, 2006;Lubitz, 2006;Rappaport, 2006;Savikhin, 2006). However, from a structural biology point of view, the atomic-resolution model, which provides a template for understanding the mechanism of the unprecedented high quantum yield of PSI in light capture and electron transfer, remains the ultimate goal.…”

Section: Introductionmentioning

confidence: 99%

Plant Photosystem I Design in the Light of Evolution

Amunts

Nelson

2009

Structure

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Photosystem I (PSI) is a membrane protein complex that catalyzes sunlight-driven transmembrane electron transfer as part of the photosynthetic machinery. Photosynthetic organisms appeared on the Earth about 3.5 billion years ago and provided an essential source of potential energy for the development of life. During the course of evolution, these primordial organisms were phagocytosed by more sophisticated eukaryotic cells, resulting in the evolvement of algae and plants. Despite the extended time interval between primordial cyanobacteria and plants, PSI has retained its fundamental mechanism of sunlight conversion. Being probably the most efficient photoelectric apparatus in nature, PSI operates with a quantum efficiency close to 100%. However, adapting to different ecological niches necessitated structural changes in the PSI design. Based on the recently solved structure of plant PSI, which revealed a complex of 17 protein subunits and 178 prosthetic groups, we analyze the evolutionary development of PSI. In addition, some aspects of PSI structure determination are discussed.

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Transient EPR Spectroscopy as Applied to Light-Induced Functional Intermediates Along the Electron Transfer Pathway in Photosystem I

Cited by 18 publications

References 96 publications

Transient EPR: using spin polarization in sequential radical pairs to study electron transfer in photosynthesis

Transient EPR: using spin polarization in sequential radical pairs to study electron transfer in photosynthesis

What you get out of high-time resolution electron paramagnetic resonance: example from photosynthetic bacteria

Plant Photosystem I Design in the Light of Evolution

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