Time-resolved EPR of the radical pair P865+.QA−. in bacterial reaction centers. Observations of transient nutations, quantum beats and envelope modulation effects

Bittl, Robert; Est, Arthur van der; Kamlowski, A.; Lubitz, Wolfgang; Stehlik, D.

doi:10.1016/0009-2614(94)00690-3

Cited by 61 publications

(63 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Following the observation of quantum beat oscillations in the transient EPR signal of P&Ai-the same phenomenon has been observed for the state Pi6& in bacterial RC (374,375). Fully deuterated RC of Rb.…”

Section: Secondary Radical Pairsupporting

confidence: 67%

See 1 more Smart Citation

Radicals and Radical Pairs in Photosynthesis

Angerhofer

Bittl

1996

Photochem & Photobiology

Self Cite

View full text Add to dashboard Cite

Section: Secondary Radical Pairsupporting

confidence: 67%

“…The samples studied by Bittl et al (375) were RC with the high-spin Fez+ substituted by the diamagnetic Zn2+ as already used by van der Est et al (370). Simulation of the time evolution of the signals was found to be qualitatively consistent with the geometry of the state Ps+65Q~ as obtained from K-band spectra (370).…”

Section: Secondary Radical Pairmentioning

confidence: 61%

Radicals and Radical Pairs in Photosynthesis

Angerhofer

Bittl

1996

Photochem & Photobiology

Self Cite

View full text Add to dashboard Cite

“…6, which shows early spectra in four successive 16-ns time windows for the wild-type and the S672C PsaB and S692C PsaA mutants. In general, the polarization patterns of spin-correlated radical pairs exhibit lifetime or Fourier broadening as well as coherence effects because of transient mutations, quantum beats, and envelope modulation (22)(23)(24)(25). Coherence effects do not make significant contributions under our experimental conditions and Fourier broadening dominates the short time behavior at X-band.…”

Section: Room Temperature Electron Spin-polarized Epr Signals At X-band-mentioning

confidence: 76%

Electron Transfer in Cyanobacterial Photosystem I

Chitnis

Valieva

et al. 2003

Journal of Biological Chemistry

Self Cite

102

View full text Add to dashboard Cite

The directionality of electron transfer in Photosystem I (PS I) is investigated using site-directed mutations in the phylloquinone (Q K ) and F X binding regions of Synnechocystis sp. PCC 6803. The kinetics of forward electron transfer from the secondary acceptor A 1 (phylloquinone) were measured in mutants using time-resolved optical difference spectroscopy and transient EPR spectroscopy. In whole cells and PS I complexes of the wildtype both techniques reveal a major, slow kinetic component of Ϸ 300 ns while optical data resolve an additional minor kinetic component of Ϸ 10 ns. Whole cells and PS I complexes from the W697F PsaA and S692C PsaA mutants show a significant slowing of the slow kinetic component, whereas the W677F PsaB and S672C PsaB mutants show a less significant slowing of the fast kinetic component. Transient EPR measurements at 260 K show that the slow phase is ϳ3 times slower than at room temperature. Simulations of the early time behavior of the spin polarization pattern of P 700 ؉ A 1 ؊ , in which the decay rate of the pattern is assumed to be negligibly small, reproduce the observed EPR spectra at 260 K during the first 100 ns following laser excitation. Thus any spin polarization from P 700 ؉ F X ؊ in this time window is very weak. From this it is concluded that the relative amplitude of the fast phase is negligible at 260 K or its rate is much less temperature-dependent than that of the slow component. Together, the results demonstrate that the slow kinetic phase results from electron transfer from Q K -A to F X and that this accounts for at least 70% of the electrons. Although the assignment of the fast kinetic phase remains uncertain, it is not strongly temperature dependent and it represents a minor fraction of the electrons being transferred. All of the results point toward asymmetry in electron transfer, and indicate that forward transfer in cyanobacterial PS I is predominantly along the PsaA branch.

show abstract

“…In addition, there are coherences between the eigenstates of the radical pair. Analysis reveals that zero quantum electron (Salikhov et at., 1990;Bittl and Kothe, 1991;Kothe et at., 1998;Zwanenburg and Hore, 1993;Kothe et at., 1994a;Kothe et at., 1994b;Bittl et at., 1994;Kiefer et at., 1999;Link et at., 2001;Heinen et at., 2002) and single quantum nuclear coherences (Kothe et at., 1998;Weber et at., 1995;Weber et at., 1997;Jeschke, 1997) are involved.…”

Section: ~-----------------------mentioning

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

View full text Add to dashboard Cite

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.

show abstract

Time-resolved EPR of the radical pair P865+.QA−. in bacterial reaction centers. Observations of transient nutations, quantum beats and envelope modulation effects

Cited by 61 publications

References 17 publications

Radicals and Radical Pairs in Photosynthesis

Radicals and Radical Pairs in Photosynthesis

Electron Transfer in Cyanobacterial Photosystem I

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

Contact Info

Product

Resources

About