Water Oxidation for Simplified Models of the Oxygen-Evolving Complex in Photosystem II

2015 ◽  
Vol 21 (51) ◽  
pp. 18821-18827 ◽  
Author(s):  
Xichen Li ◽  
Per E. M. Siegbahn
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Oxygen Evolving Complex ◽  
Simplified Models ◽  
Oxygen Evolving

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

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

Large-scale QM/MM calculations of the CaMn4O5 cluster in the S3 state of the oxygen evolving complex of photosystem II. Comparison between water-inserted and no water-inserted structures

2017 ◽  
Vol 198 ◽  
pp. 83-106 ◽  
Author(s):  
Mitsuo Shoji ◽  
Hiroshi Isobe ◽  
Takahito Nakajima ◽  
Yasuteru Shigeta ◽  
Michihiro Suga ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Large Scale ◽  
Geometrical Structure ◽  
Bond Formation ◽  
Oxygen Evolving Complex ◽  
Computational Results ◽  
Hydroxide Anion ◽  
The Right ◽  
Oxygen Evolving

Large-scale QM/MM calculations were performed to elucidate an optimized geometrical structure of a CaMn4O5 cluster with and without water insertion in the S3 state of the oxygen evolving complex (OEC) of photosystem II (PSII). The left (L)-opened structure was found to be stable under the assumption of no hydroxide anion insertion in the S3 state, whereas the right (R)-opened structure became more stable if one water molecule is inserted to the Mn4Ca cluster. The optimized Mna(4)–Mnd(1) distance determined by QM/MM was about 5.0 Å for the S3 structure without an inserted hydroxide anion, but this is elongated by 0.2–0.3 Å after insertion. These computational results are discussed in relation to the possible mechanisms of O–O bond formation in water oxidation by the OEC of PSII.

scholarly journals Bio-Inspired Molecular Catalysts for Water Oxidation

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1068
Author(s):  
Dan Xiao ◽  
Jennifer Gregg ◽  
K. V. Lakshmi ◽  
Peter J. Bonitatibus
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Oxidation Reaction ◽  
Energy Production ◽  
Photosynthetic Reaction Center ◽  
Transition Metal Catalysts ◽  
Environmentally Benign ◽  
Oxygen Evolving Complex ◽  
Molecular Catalysts ◽  
Oxygen Evolving

The catalytic tetranuclear manganese-calcium-oxo cluster in the photosynthetic reaction center, photosystem II, provides an excellent blueprint for light-driven water oxidation in nature. The water oxidation reaction has attracted intense interest due to its potential as a renewable, clean, and environmentally benign source of energy production. Inspired by the oxygen-evolving complex of photosystem II, a large of number of highly innovative synthetic bio-inspired molecular catalysts are being developed that incorporate relatively cheap and abundant metals such as Mn, Fe, Co, Ni, and Cu, as well as Ru and Ir, in their design. In this review, we briefly discuss the historic milestones that have been achieved in the development of transition metal catalysts and focus on a detailed description of recent progress in the field.

‘Photosystem II: the water splitting enzyme of photosynthesis and the origin of oxygen in our atmosphere’

2016 ◽  
Vol 49 ◽  
Author(s):  
James Barber
Keyword(s):  
Photosystem Ii ◽  
Water Splitting ◽  
Water Oxidation ◽  
18Th Century ◽  
Metal Cluster ◽  
Oxygen Evolving Complex ◽  
Structural Details ◽  
Unlimited Supply ◽  
Lipid Environment ◽  
Oxygen Evolving

AbstractAbout 3 billion years ago an enzyme emerged which would dramatically change the chemical composition of our planet and set in motion an unprecedented explosion in biological activity. This enzyme used solar energy to power the thermodynamically and chemically demanding reaction of water splitting. In so doing it provided biology with an unlimited supply of reducing equivalents needed to convert carbon dioxide into the organic molecules of life while at the same time produced oxygen to transform our planetary atmosphere from an anaerobic to an aerobic state. The enzyme which facilitates this reaction and therefore underpins virtually all life on our planet is known as Photosystem II (PSII). It is a pigment-binding, multisubunit protein complex embedded in the lipid environment of the thylakoid membranes of plants, algae and cyanobacteria. Today we have detailed understanding of the structure and functioning of this key and unique enzyme. The journey to this level of knowledge can be traced back to the discovery of oxygen itself in the 18th-century. Since then there has been a sequence of mile stone discoveries which makes a fascinating story, stretching over 200 years. But it is the last few years that have provided the level of detail necessary to reveal the chemistry of water oxidation and O–O bond formation. In particular, the crystal structure of the isolated PSII enzyme has been reported with ever increasing improvement in resolution. Thus the organisational and structural details of its many subunits and cofactors are now well understood. The water splitting site was revealed as a cluster of four Mn ions and a Ca ion surrounded by amino-acid side chains, of which seven provide direct ligands to the metals. The metal cluster is organised as a cubane structure composed of three Mn ions and a Ca2+ linked by oxo-bonds with the fourth Mn ion attached to the cubane. This structure has now been synthesised in a non-protein environment suggesting that it is a totally inorganic precursor for the evolution of the photosynthetic oxygen-evolving complex. In summary, the overall structure of the catalytic site has given a framework on which to build a mechanistic scheme for photosynthetic dioxygen generation and at the same time provide a blue-print and incentive to develop catalysts for artificial photo-electrochemical systems to split water and generate renewable solar fuels.

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