Dual-Mode EPR Study of New Signals from the S<sub>3</sub>-State of Oxygen-Evolving Complex in Photosystem II

Matsukawa, Takaya; Mino, Hiroyuki; Yoneda, Daiki; Kawamori, Asako

doi:10.1021/bi9818570

Cited by 95 publications

(110 citation statements)

References 28 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Parallel-mode EPR studies by Matsukawa and co-workers have shown the presence of EPR resonances at g = 12 and 8 that are best simulated by an S = 1 excited-state spin species in the S 3 state. 87 The authors rationalize these results as arising from a coupling between the S = ½ complex, characterized by the MLS EPR signal, interacting with an S = ½ radical produced during the S 3 transition that leads to the disappearance of the MLS and generation of an integer spin state.…”

Section: Implication To the Mechanism Of Water Oxidationmentioning

confidence: 93%

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

et al. 2000

View full text Add to dashboard Cite

The oxygen-evolving complex of Photosystem II in plants and cyanobacteria catalyzes the oxidation of two water molecules to one molecule of dioxygen. A tetranuclear Mn complex is believed to cycle through five intermediate states (S 0 -S 4 ) to couple the four-electron oxidation of water with the one-electron photochemistry occurring at the Photosystem II reaction center. We have used X-ray absorption spectroscopy to study the local structure of the Mn complex and have proposed a model for it, based on studies of the Mn K-edges and the extended X-ray absorption fine structure of the S 1 and S 2 states. The proposed model consists of two di-μ-oxo-bridged binuclear Mn units with Mn-Mn distances of ~2.7 Å that are linked to each other by a mono-μ-oxo bridge with a Mn-Mn separation of ~3.3 Å. The Mn-Mn distances are invariant in the native S 1 and S 2 states. This report describes the application of X-ray absorption spectroscopy to S 3 samples created under physiological conditions with saturating flash illumination. Significant changes are observed in the Mn-Mn distances in the S 3 state compared to the S 1 and the S 2 states. The two 2.7 Å Mn-Mn distances that characterize the di-μ-oxo centers in the S 1 and S 2 states are lengthened to ~2.8 and 3.0 Å in the S 3 state, respectively. The 3.3 Å Mn-Mn and Mn-Ca distances also increase by 0.04-0.2 Å. These changes in Mn-Mn distances are interpreted as consequences of the onset of substrate/water oxidation in the S 3 state. Mn-centered oxidation is evident during the S 0 →S 1 and S 1 →S 2 transitions. We propose that the changes in Mn-Mn distances during the S 2 →S 3 transition are the result of ligand or water oxidation, leading to the Supporting Information Available: E-space S 3 state EXAFS spectrum; the data in k-space and the background that was removed to reduce the low-frequency contributions that show up as peaks at <1 Å in the Fourier transform; and the Fourier isolate of the k-space S 3 spectrum, shown overplotted on the S 3 EXAFS spectrum (PDF). This material is available free of charge via the Internet at http:// pubs.acs.org. NIH Public Access

show abstract

Section: Implication To the Mechanism Of Water Oxidationmentioning

confidence: 93%

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

et al. 2000

View full text Add to dashboard Cite

show abstract

“…The EPR spectrum of S 3 was first reported by Matsukawa, et al, who also reported a phenomenological simulation. [236] 6.6. …”

Section: Angewandte Chemiementioning

confidence: 99%

The Possible Role of Proton‐Coupled Electron Transfer (PCET) in Water Oxidation by Photosystem II

2007

View full text Add to dashboard Cite

All higher life forms use oxygen and respiration as their primary energy source. The oxygen comes from water by solar-energy conversion in photosynthetic membranes. In green plants, light absorption in photosystem II (PSII) drives electron-transfer activation of the oxygen-evolving complex (OEC). The mechanism of water oxidation by the OEC has long been a subject of great interest to biologists and chemists. With the availability of new molecular-level protein structures from X-ray crystallography and EXAFS, as well as the accumulated results from numerous experiments and theoretical studies, it is possible to suggest how water may be oxidized at the OEC. An integrated sequence of light-driven reactions that exploit coupled electron-proton transfer (EPT) could be the key to water oxidation. When these reactions are combined with long-range proton transfer (by sequential local proton transfers), it may be possible to view the OEC as an intricate structure that is "wired for protons".

show abstract

“…A variety of techniques have been applied, including electron paramagnetic resonance (EPR) spectroscopy Boussac et al 1989;Britt et al 2004;Britt et al 2000;Kulik et al 2005a;Kulik et al 2005b;Kulik et al 2005c;Matsukawa et al 1999;Messinger et al 1997a;Messinger et al 1997b;Miller & Brudvig 1991;Mino & Kawamori 2001;Nugent et al 1997;Peloquin & Britt 2001;Peloquin et al 1998;Peloquin et al 2000;Poluektov et al 2005;Razeghifard & Pace 1999), X-ray absorption spectroscopy (XAS) (Dau et al 2001;Dau et al 2003;Dau et al 2004;Grabolle et al 2006;Hasegawa et al 1999;Haumann et al 2005a;Haumann et al 2005b;Iuzzolino et al 1998;Liang et al 2000;Mishra et al 2007;Riggs-Gelasco et al 1996;Robblee et al 2002;Sauer & Yachandra 2004;Sauer et al 2005;Stemmler et al 1997;Yachandra 2002;Yachandra et al 1986;Yachandra et al 1987;Yano et al 2006;Yano et al 2005b), Fourier transform infrared (FTIR) spectroscopy (Chu et al 2004;Debus et al 2005;…”

Section: Structure and Mechanism Of The Oecmentioning

confidence: 99%

Computational insights into the O2-evolving complex of photosystem II

et al. 2008

View full text Add to dashboard Cite

Mechanistic investigations of the water-splitting reaction of the oxygen-evolving complex (OEC) of photosystem II (PSII) are fundamentally informed by structural studies. Many physical techniques have provided important insights into the OEC structure and function, including X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy as well as mass spectrometry (MS), electron paramagnetic resonance (EPR) spectroscopy and Fourier transform infrared spectroscopy applied in conjunction with mutagenesis studies. However, experimental studies have yet to yield consensus as to the exact configuration of the catalytic metal cluster and its ligation scheme. Computational modeling studies, including density functional (DFT) theory combined with quantum mechanics/molecular mechanics (QM/MM) hybrid methods for explicitly including the influence of the surrounding protein, have proposed chemically satisfactory models of the fully ligated OEC within PSII that are maximally consistent with experimental results. The inorganic core of these models is similar to the crystallographic model upon which they were based but comprises important modifications due to structural refinement, hydration and proteinaceous ligation which improve agreement with a wide range of experimental data. The computational models are useful for rationalizing spectroscopic and crystallographic results and for building a complete structure-based mechanism of water-splitting in PSII as described by the intermediate oxidation states of the OEC. This review summarizes these recent advances in QM/MM modeling of PSII within the context of recent experimental studies.

show abstract

Dual-Mode EPR Study of New Signals from the S₃-State of Oxygen-Evolving Complex in Photosystem II

Cited by 95 publications

References 28 publications

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

The Possible Role of Proton‐Coupled Electron Transfer (PCET) in Water Oxidation by Photosystem II

Computational insights into the O2-evolving complex of photosystem II

Contact Info

Product

Resources

About

Dual-Mode EPR Study of New Signals from the S3-State of Oxygen-Evolving Complex in Photosystem II

Cited by 95 publications

References 28 publications

Structural Change of the Mn Cluster during the S2→S3 State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S2→S3 State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

The Possible Role of Proton‐Coupled Electron Transfer (PCET) in Water Oxidation by Photosystem II

Computational insights into the O2-evolving complex of photosystem II

Contact Info

Product

Resources

About

Dual-Mode EPR Study of New Signals from the S₃-State of Oxygen-Evolving Complex in Photosystem II

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy