How does ammonia bind to the oxygen-evolving complex in the S2state of photosynthetic water oxidation? Theoretical support and implications for the W1 substitution mechanism

2016 ◽  
Vol 18 (46) ◽  
pp. 31551-31565 ◽  
Author(s):  
Yu Guo ◽  
Lan-Lan He ◽  
Dong-Xia Zhao ◽  
Li-Dong Gong ◽  
Cui Liu ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Mechanistic Study ◽  
Oxygen Evolving Complex ◽  
Theoretical Support ◽  
Substitution Mechanism ◽  
Oxygen Evolving ◽  
Photosynthetic Water Oxidation

The mechanistic study shows that NH3substitutes W1 rather than O5 of the OEC in the S2state and leaves in the S4′ state.

scholarly journals Using small molecule complexes to elucidate features of photosynthetic water oxidation

2007 ◽  
Vol 363 (1494) ◽  
pp. 1271-1281 ◽  
Author(s):  
Kristof Meelich ◽  
Curtis M Zaleski ◽  
Vincent L Pecoraro
Keyword(s):  
Water Oxidation ◽  
Spectroscopic Characterization ◽  
Structural Features ◽  
Oxygen Evolving Complex ◽  
Model Complexes ◽  
Small Model ◽  
Oxygen Evolving ◽  
Photosynthetic Water Oxidation ◽  
Insight Into

The molecular oxygen produced in photosynthesis is generated via water oxidation at a manganese–calcium cluster called the oxygen-evolving complex (OEC). While studies in biophysics, biochemistry, and structural and molecular biology are well known to provide deeper insight into the structure and workings of this system, it is often less appreciated that biomimetic modelling provides the foundation for interpreting photosynthetic reactions. The synthesis and characterization of small model complexes, which either mimic structural features of the OEC or are capable of providing insight into the mechanism of O 2 evolution, have become a vital contributor to this scientific field. Our group has contributed to these findings in recent years through synthesis of model complexes, spectroscopic characterization of these systems and probing the reactivity in the context of water oxidation. In this article we describe how models have made significant contributions ranging from understanding the structure of the water-oxidation centre (e.g. contributions to defining a tetrameric Mn 3 Ca-cluster with a dangler Mn) to the ability to discriminate between different mechanistic proposals (e.g. showing that the Babcock scheme for water oxidation is unlikely).

scholarly journals Photosynthetic water oxidation: binding and activation of substrate waters for O–O bond formation

2015 ◽  
Vol 185 ◽  
pp. 37-50 ◽  
Author(s):  
David J. Vinyard ◽  
Sahr Khan ◽  
Gary W. Brudvig
Keyword(s):  
Water Oxidation ◽  
Bond Formation ◽  
Oxygen Evolving Complex ◽  
Amino Acid Residues ◽  
Water Binding ◽  
State Dependent ◽  
Oxygen Evolving ◽  
Electronic And Structural Properties ◽  
Photosynthetic Water Oxidation ◽  
Insight Into

Photosynthetic water oxidation occurs at the oxygen-evolving complex (OEC) of Photosystem II (PSII). The OEC, which contains a Mn4CaO5inorganic cluster ligated by oxides, waters and amino-acid residues, cycles through five redox intermediates known as Sistates (i= 0–4). The electronic and structural properties of the transient S4intermediate that forms the O–O bond are not well understood. In order to gain insight into how water is activated for O–O bond formation in the S4intermediate, we have performed a detailed analysis of S-state dependent substrate water binding kinetics taking into consideration data from Mn coordination complexes. This analysis supports a model in which the substrate waters are both bound as terminal ligands and reactviaa water-nucleophile attack mechanism.

scholarly journals Simulation of the isotropic EXAFS spectra for the S2 and S3 structures of the oxygen evolving complex in photosystem II

2015 ◽  
Vol 112 (13) ◽  
pp. 3979-3984 ◽  
Author(s):  
Xichen Li ◽  
Per E. M. Siegbahn ◽  
Ulf Ryde
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Density Functional ◽  
Structural Changes ◽  
Complete Agreement ◽  
Oxygen Evolving Complex ◽  
Chemical Modeling ◽  
Oxygen Evolving ◽  
High Degree ◽  
Exafs Spectra

Most of the main features of water oxidation in photosystem II are now well understood, including the mechanism for O–O bond formation. For the intermediate S2 and S3 structures there is also nearly complete agreement between quantum chemical modeling and experiments. Given the present high degree of consensus for these structures, it is of high interest to go back to previous suggestions concerning what happens in the S2–S3 transition. Analyses of extended X-ray adsorption fine structure (EXAFS) experiments have indicated relatively large structural changes in this transition, with changes of distances sometimes larger than 0.3 Å and a change of topology. In contrast, our previous density functional theory (DFT)(B3LYP) calculations on a cluster model showed very small changes, less than 0.1 Å. It is here found that the DFT structures are also consistent with the EXAFS spectra for the S2 and S3 states within normal errors of DFT. The analysis suggests that there are severe problems in interpreting EXAFS spectra for these complicated systems.

scholarly journals Recent pulsed EPR studies of the Photosystem II oxygen-evolving complex: implications as to water oxidation mechanisms

2004 ◽  
Vol 1655 ◽  
pp. 158-171 ◽  
Author(s):  
R.David Britt ◽  
Kristy A Campbell ◽  
Jeffrey M Peloquin ◽  
M.Lane Gilchrist ◽  
Constantino P Aznar ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Oxygen Evolving Complex ◽  
Pulsed Epr ◽  
Oxygen Evolving ◽  
Oxidation Mechanisms

A model for the water-oxidation and recovery systems of the oxygen-evolving complex

2014 ◽  
Vol 43 (8) ◽  
pp. 3063-3071 ◽  
Author(s):  
Takeshi Yatabe ◽  
Mitsuhiro Kikkawa ◽  
Takahiro Matsumoto ◽  
Hidetaka Nakai ◽  
Kenji Kaneko ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Oxygen Evolving Complex ◽  
Oxygen Evolving

Theory of chemical bonds in metalloenzymes XXI. Possible mechanisms of water oxidation in oxygen evolving complex of photosystem II

2018 ◽  
Vol 116 (5-6) ◽  
pp. 717-745 ◽  
Author(s):  
Kizashi Yamaguchi ◽  
Mitsuo Shoji ◽  
Hiroshi Isobe ◽  
Shusuke Yamanaka ◽  
Takashi Kawakami ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Oxygen Evolving Complex ◽  
Chemical Bonds ◽  
Theory Of Chemical Bonds ◽  
Oxygen Evolving
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