Primary reactions of oxygenic photosynthesis

Witt, H. T.

doi:10.1002/bbpc.19961001202

Cited by 57 publications

(22 citation statements)

References 126 publications

(45 reference statements)

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“…During the S 2 →S 3 transition, the substrate water molecule bound to Mn(4) is deprotonated, consistently with electrochromism data (Haumann & Junge 1996;Junge et al 2002;Lavergne & Junge 1993;Schlodder & Witt 1999;Witt 1996), and the oxidation state of Mn(4) is advanced from III to IV. These changes induce inter-ligand proton transfer from the HO -ligand of Mn (3) to the hydrogen bonded HO -ligand of Mn(4), strengthening the attractive interactions between Mn(4) and the HO -ligand of Mn(3), forming a μ-oxo bridge between Mn(3) and Mn (4), and transforming the HO -ligand of Mn(4) into a water ligand (the HO -proton acceptor is regenerated by deprotonation of the water ligand in the S 0 →S 1 transition).…”

Section: Qm/mm Mechanistic Model Of Water Splittingsupporting

confidence: 75%

Computational insights into the O2-evolving complex of photosystem II

et al. 2008

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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.

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Section: Qm/mm Mechanistic Model Of Water Splittingsupporting

confidence: 75%

Computational insights into the O2-evolving complex of photosystem II

et al. 2008

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“…For the S 2 → S 3 transition as initiated by absorption of the second photon, the pH-independent release of one proton as well as the electrochromism data on charge accumulation suggest release of exactly one proton from the Mn complex [105,[115][116][117]134]. The rate constant is pH-dependent and the kinetic isotope effect is more sizable (temperature-dependent k D /k H -ratio of 1.4-2.)…”

Section: Second Flash S 2 → S 3 Transitionmentioning

confidence: 99%

The manganese complex of photosystem II in its reaction cycle—Basic framework and possible realization at the atomic level

Dau

Haumann

2008

Coordination Chemistry Reviews

369

457

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“…The main constituents of the photosynthetic machinery are well conserved between plants and cyanobacteria. The latter are used as model systems for the investigation of the structure and function of the large protein complexes, PSI and PSII, which catalyse the rst and most important step of photosynthesis, the light-induced charge separation (for a review on photosynthesis see Witt (1996)). The two photosystems function in series, coupled by a pool of plastoquinone, the cytochrome b 6 f complex and the soluble electron carrier * Author for correspondence (pfromme@asu.edu).…”

Section: Introductionmentioning

confidence: 99%

Functional implications on the mechanism of the function of photosystem II including water oxidation based on the structure of photosystem II

Fromme

Kern

Loll

et al. 2002

Phil. Trans. R. Soc. Lond. B

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The structure of photosystem I at 3.8 A c resolution illustrated the main structural elements of the wateroxidizing photosystem II complex, including the constituents of the electron transport chain. The location of the Mn cluster within the complex has been identi ed for the rst time to our knowledge. At this resolution, no individual atoms are visible, however, the electron density of the Mn cluster can be used to discuss both the present models of the Mn cluster as revealed from various spectroscopic methods and the implications for the mechanisms of water oxidation. Twenty-six chlorophylls from the antenna system of photosystem II have been identi ed. They are arranged in two layers, one close to the stromal side and one close to the lumenal side. Comparing the structure of the antenna system of photosystem II with the chlorophyll arrangement in photosystem I, which was recently determined at 2.5 A c resolution shows that photosystem II lacks the central domain of the photosystem I antenna, which is discussed in respect of the repair cycle of photosystem II due to photoinhibition.

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Primary reactions of oxygenic photosynthesis

Cited by 57 publications

References 126 publications

Computational insights into the O2-evolving complex of photosystem II

Computational insights into the O2-evolving complex of photosystem II

The manganese complex of photosystem II in its reaction cycle—Basic framework and possible realization at the atomic level

Functional implications on the mechanism of the function of photosystem II including water oxidation based on the structure of photosystem II

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