Highly Efficient Spectral Hole-Burning in Oxygen-Evolving Photosystem II Preparations

Hughes, Joseph L.; Prince, Barry J.; Krausz, Elmars; Smith, Paul J.; Pace, Ronald; Riesen, Hans

doi:10.1021/jp0492523

Cited by 45 publications

(100 citation statements)

References 68 publications

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“…These coupling constants are calculated in the dipole-dipole approximation, since the distances between the pigments are >20 Å. Table 3 are ~10 cm -1 , in agreement with the relatively low (on the order of tens of ps) CP43→RC EET rates observed for intact oxygen-evolving PSII core complexes at low temperature 50 .…”

Section: Assignment Of the A And B States To Particular Chlorophylls supporting

confidence: 74%

The CP43 Proximal Antenna Complex of Higher Plant Photosystem II Revisited: Modeling and Hole Burning Study. I

et al. 2008

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The CP43 core antenna complex of Photosystem II is known to possess two quasi-degenerate "red"-trap states [R. Jankowiak et al. J. Phys. Chem. B 2000, 104, 11805]. It has been suggested recently [V. Zazubovich and R. Jankowiak, J. Lum. 2007, 127, 245] that the site distribution functions (SDFs) of the red states (A and B) are uncorrelated and that narrow holes are burned in the subpopulations of chlorophylls (Chls) from states A and B that are the lowestenergy Chl in their complex and previously thought not to transfer energy. This model of uncorrelated excitation energy transfer (EET) between the quasi-degenerate bands is expanded by taking into account both electron-phonon and vibrational coupling. The model is applied to fit simultaneously absorption, emission, zero-phonon action, and transient hole burned (HB) spectra obtained for the CP43 complex with minimized contribution from aggregation. It is demonstrated that the above listed spectra can be well fitted using the uncorrelated EET model, providing strong evidence for the existence of efficient energy transfer between the two lowest energy states A and B (either from A to B or from B to A) in CP43. Possible candidate Chls for the low-energy A and B states are discussed, providing a link between CP43 structure and spectroscopy. Finally, we propose that persistent holes originate from regular NPHB accompanied by the redistribution of oscillator strength due to excitonic interactions, rather than photoconversion involving Chl-protein hydrogen bonding as suggested before [J.L. Hughes et al., Biochemistry 45, 12345, 2006]. In the accompanying paper (II) it is demonstrated that the model discussed in this manuscript is consistent with excitonic calculations, which also provide very good fits to both transient and persistent HB spectra obtained under non-line narrowing conditions.

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Section: Assignment Of the A And B States To Particular Chlorophylls supporting

confidence: 74%

The CP43 Proximal Antenna Complex of Higher Plant Photosystem II Revisited: Modeling and Hole Burning Study. I

et al. 2008

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“…Although we found very similar intrinsic rate constants for the primary charge separation in intact PSII cores (18) and in isolated D1͞D2-cyt b559 RCs (9), and also supported by studies on CP47͞RCs (11), the identity of the electron transfer mechanism and the rates in intact PSII and RCs has been questioned recently (20)(21)(22)(23) (for recent reviews see refs. 4, 24, and 25).…”

supporting

confidence: 79%

Kinetics and mechanism of electron transfer in intact photosystem II and in the isolated reaction center: Pheophytin is the primary electron acceptor

Holzwarth

Müller²,

Reus³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

320

316

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The mechanism and kinetics of electron transfer in isolated D1͞ D2-cyt b559 photosystem (PS) II reaction centers (RCs) and in intact PSII cores have been studied by femtosecond transient absorption and kinetic compartment modeling. For intact PSII, a component of Ϸ1.5 ps reflects the dominant energy-trapping kinetics from the antenna by the RC. A 5.5-ps component reflects the apparent lifetime of primary charge separation, which is faster by a factor of 8 -12 than assumed so far. The 35-ps component represents the apparent lifetime of formation of a secondary radical pair, and the Ϸ200-ps component represents the electron transfer to the Q A acceptor. In isolated RCs, the apparent lifetimes of primary and secondary charge separation are Ϸ3 and 11 ps, respectively. It is shown (i) that pheophytin is reduced in the first step, and (ii) that the rate constants of electron transfer in the RC are identical for PSII cores and for isolated RCs. We interpret the first electron transfer step as electron donation from the primary electron donor Chl acc D1. Thus, this mechanism, suggested earlier for isolated RCs at cryogenic temperatures, is also operative in intact PSII cores and in isolated RCs at ambient temperature. The effective rate constant of primary electron transfer from the equilibrated RC* excited state is 170 -180 ns ؊1 , and the rate constant of secondary electron transfer is 120 -130 ns ؊1 .charge separation ͉ photosynthesis ͉ ultrafast spectroscopy ͉ D1͞D2-cytb559 ͉ femtosecond absorption P hotosystem (PS) II cores, whose structure has recently been determined to a resolution of 3.5-3.2 Å (1-3), consist of the antenna polypeptides CP43 and CP47, which carry 13 and 16 chlorophyll (Chl) a molecules, respectively. They contain furthermore the D1͞D2-cyt b559 reaction center (RC) polypeptides, which bind the pigments of the electron transfer chain [four Chls, two pheophytins (Pheo), and two quinones] and two additional antenna Chls (the so-called Chl z D1 and Chl z D2 molecules). The isolated RC (D1-D2-cyt b559 ) lacks the quinone acceptors and is thus only able to create a short-lived radical pair (RP) (see review in ref. 4).There exists presently no agreement on the mechanism of the primary events of energy and electron transfer in the isolated RC complex (see refs. 4-6 for recent reviews). Early studies suggested an apparent Ϸ3-ps charge separation lifetime in the RC at room temperature (7,8) in agreement with later studies (9, 10). Andrizhiyevskaya et al. (11) recently also proposed a model with an Ϸ3-ps charge separation. A somewhat slower charge separation of Ϸ8 ps has been reported by Wasielewski and coworkers (12), whereas more recent data from the same group were interpreted in terms of a 2-to 5-ps charge separation time (13). Substantially shorter charge separation times of 1 ps (14) and 0.4 ps (at 240 K) have been reported by Groot et al. (15). At the other extreme, a 1 order of magnitude longer charge separation time of Ϸ21 ps has been suggested by Klug and coworkers (16,17). Probably the largest ...

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“…The relative weight of the two pathways is determined by specific realization of the disorder in site energies (Novoderezhkin et al 2007). We note here that a recently discovered phenomenon could change our view on primary electron transfer in PS II: a low-lying homogeneously broadened excited state with small oscillator strength was found that is capable of initiating charge separation (Hughes et al 2004;Krausz et al 2005;Hughes et al 2006). At present, this effect is largely unexplained and therefore we will refrain from further speculations.…”

Section: Trapping Of Lightmentioning

confidence: 75%

Photosystem II: The machinery of photosynthetic water splitting

2008

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This review summarizes our current state of knowledge on the structural organization and functional pattern of photosynthetic water splitting in the multimeric Photosystem II (PS II) complex, which acts as a light-driven water: plastoquinone-oxidoreductase. The overall process comprises three types of reaction sequences: (1) photon absorption and excited singlet state trapping by charge separation leading to the ion radical pair [Formula: see text] formation, (2) oxidative water splitting into four protons and molecular dioxygen at the water oxidizing complex (WOC) with P680+* as driving force and tyrosine Y(Z) as intermediary redox carrier, and (3) reduction of plastoquinone to plastoquinol at the special Q(B) binding site with Q(A)-* acting as reductant. Based on recent progress in structure analysis and using new theoretical approaches the mechanism of reaction sequence (1) is discussed with special emphasis on the excited energy transfer pathways and the sequence of charge transfer steps: [Formula: see text] where (1)(RC-PC)* denotes the excited singlet state (1)P680* of the reaction centre pigment complex. The structure of the catalytic Mn(4)O(X)Ca cluster of the WOC and the four step reaction sequence leading to oxidative water splitting are described and problems arising for the electronic configuration, in particular for the nature of redox state S(3), are discussed. The unravelling of the mode of O-O bond formation is of key relevance for understanding the mechanism of the process. This problem is not yet solved. A multistate model is proposed for S(3) and the functional role of proton shifts and hydrogen bond network(s) is emphasized. Analogously, the structure of the Q(B) site for PQ reduction to PQH(2) and the energetic and kinetics of the two step redox reaction sequence are described. Furthermore, the relevance of the protein dynamics and the role of water molecules for its flexibility are briefly outlined. We end this review by presenting future perspectives on the water oxidation process.

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Highly Efficient Spectral Hole-Burning in Oxygen-Evolving Photosystem II Preparations

Cited by 45 publications

References 68 publications

The CP43 Proximal Antenna Complex of Higher Plant Photosystem II Revisited: Modeling and Hole Burning Study. I

The CP43 Proximal Antenna Complex of Higher Plant Photosystem II Revisited: Modeling and Hole Burning Study. I

Kinetics and mechanism of electron transfer in intact photosystem II and in the isolated reaction center: Pheophytin is the primary electron acceptor

Photosystem II: The machinery of photosynthetic water splitting

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