研究者詳細 - 沈　建仁

論文 - 沈　建仁

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Spatially Separated Photosystem II and a Silicon Photoelectrochemical Cell for Overall Water Splitting: A Natural-Artificial Photosynthetic Hybrid 査読国際誌

Wangyin Wang, Hong Wang, Qingjun Zhu, Wei Qin, Guangye Han, Jian-Ren Shen, Xu Zong, Can Li

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 ( 32 ) 9229 - 9233 2016年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H-2 and O-2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems.

DOI： 10.1002/anie.201604091

Structure and energy transfer pathways of the plant photosystem I-LHCI supercomplex 査読国際誌

Michihiro Suga, Xiaochun Qin, Tingyun Kuang, Jian-Ren Shen

CURRENT OPINION IN STRUCTURAL BIOLOGY 39 46 - 53 2016年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CURRENT BIOLOGY LTD

Photosystem I (PSI) is one of the two photosystems in oxygenic photosynthesis, and absorbs light energy to generate reducing power for the reduction of NADP+ to NADPH with a quantum efficiency close to 100%. The plant PSI core forms a supercomplex with light-harvesting complex I (LHCI) with a total molecular weight of over 600 kDa. Recent X-ray structure analysis of the PSI-LHCI membrane-protein supercomplex has revealed detailed arrangement of the light-harvesting pigments and other cofactors especially within LHCI. Here we introduce the overall structure of the PSI-LHCI supercomplex, and then focus on the excited energy transfer (EET) pathways from LHCI to the PSI core and photoprotection mechanisms based on the structure obtained.

DOI： 10.1016/j.sbi.2016.04.004

Oxygen-Evolving Porous Glass Plates Containing the Photosynthetic Photosystem II Pigment-Protein Complex 査読国際誌

Tomoyasu Noji, Keisuke Kawakami, Jian-Ren Shen, Takehisa Dewa, Mamoru Nango, Nobuo Kamiya, Shigeru Itoh, Tetsuro Jin

LANGMUIR 32 ( 31 ) 7796 - 7805 2016年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

The development of artificial photosynthesis has focused on the efficient coupling of reaction at photoanode and cathode, wherein the production of hydrogen (or energy carriers) is coupled to the electrons derived from water splitting reactions. The natural photosystem II (PSII) complex splits water efficiently using light energy. The PSII complex is a large pigment protein complex (20 nm in diameter) containing a manganese cluster. A new photoanodic device was constructed incorporating stable PSII purified from a cyanobacterium Thermosynechococcus vulcanus through immobilization within 20 or 50 nm nanopores contained in porous glass plates (PGPs). PSII in the nanopores retained its native structure and high photoinduced water splitting activity. The photocatalytic rate (turnover frequency) of PSII in PGP was enhanced 11-fold compared to that in solution, yielding a rate of 50-300 mol e(-) /(mol PSII.s) with 2,6-dichloroindophenol (DCIP) as an electron acceptor. The PGP system realized high local concentrations of PSII and DCIP to enhance the collisional reactions in nanotubes with low disturbance of light penetration. The system allows direct visualization/determination of the reaction inside the nanotubes, which contributes to optimize the local reaction condition. The PSII/PGP device will substantively contribute to the construction of artificial photosynthesis using water as the ultimate electron source.

DOI： 10.1021/acs.langmuir.6b02106

Crystal structure of plant PSI-LHCI supercomplex and its energy transfer mechanism

Xiaochun Qin, Michihiro Suga, Tingyun Kuang, Jianren Shen

Kexue Tongbao/Chinese Science Bulletin 61 ( 19 ) 2163 - 2175 2016年7月

記述言語：中国語掲載種別：研究論文（学術雑誌）出版者・発行元：Chinese Academy of Sciences

Photosynthesis uses light energy from the sun to convert CO2 and water into carbohydrates and oxygen, thus sustaining all aerobic life forms on Earth. Energy conversion in photosynthesis is carried out by two large membrane-protein complexes: photosystemI(PSI) and photosystemII(PSII). In higher plants, the PSIcore is surrounded by a belt of 4 light-harvestingIsubunits (LHCIor Lhca), forming a PSI-LHCIsupercomplex. The PSI-LHCIsupercomplex is an extremely efficient solar energy converter with a quantum efficiency close to 100%. In order to reveal the mechanism of energy harvesting and transfer within this large pigment-protein complex, it is essential to solve its crystal structure. The structure of the PSI-LHCIsupercomplex has been analyzed at a resolution up to 3.3 Å previously. However, this resolution was not enough to elucidate the detailed mechanism of light-harvesting and energy transfer in this complex. Recently we succeeded in analyzing the structure of the PSI-LHCIsupercomplex from pea at 2.8 Å resolution (1). Our studies showed that the PSI-LHCIsupercomplex contains 16 different subunits (including 12 core subunits PsaA-L and 4 LHCIsubunits Lhca1-4) and 205 cofactors (143 chlorophylls a, 12 chlorophylls b, 26 β-carotenes, 5 luteins, 4 violaxanthin, 10 lipids), with a total molecular mass of 600 kD. Our results identified chlorophyll a, chlorophyll b, and some carotenoids in the 4 LHCIsubunits for the first time, and revealed the differences in the structures of the 4 LHCI subunits, their interactions, and the interactions between them and the PSIcore subunits. Comparison among the available six structures of the Lhc family members (Lhca1 to Lhca4, LHCIIand CP29) revealed that, although all these Lhc proteins have a highly conserved second protein structure, notable differences were found in the two loop regions AC and BC as well as the N-terminal region. Most pigments are arranged at the same position except some distinct differences among different Lhc subunits in the position of several Chls bound at the interface between adjacent Lhca complexes, and between Lhca and PSIcore complex. Based on the structure resolved, 4 plausible energy transfer pathways (1Bs, 1Fl, 2Js, 3As/l) from LHCIto the PSIcore complex were deduced. Red forms of Chls were found to be involved in energy transfer from each Lhca to PSIcore. Our structure revealed that each Lhca binds a red chlorophyll dimer of Chl a3-Chl a9, which contribute to red-shifted spectra of Lhca complexes and have a pronounced effect on the energy transfer and trapping in the whole PSI-LHCIcomplex. All the four red dimers locate at the interface between LHCIand PSIcore complex, which looks like four bridges connecting Lhca with the core. The Chl-Chl interactions between each Lhca and the core complex suggested that excitation energy from the LHCIbelt to the PSIcore would mainly flow via Lhca1 and Lhca3. In this review, we discuss the detailed structure of the PSI-LHCIsupercomplex and the possible energy transfer mechanism within it. Taken together, this structure provides a solid structural basis for our understanding on energy transfer and photoprotection mechanisms within PSI-LHCIsupercomplex, and thus will be a big step forward toward understanding the mechanisms of photosynthesis.

DOI： 10.1360/N972016-00217

Current Insights to Enhance Hydrogen Production by Photosynthetic Organisms

Roshan Sharma Poudyal, Indira Tiwari, Mohammad Mahdi Najafpour, Dmitry A. Los, Robert Carpentier, Jian-Ren Shen, Suleyman I. Allakhverdiev

Hydrogen Science and Engineering: Materials, Processes, Systems and Technology 1 461 - 487 2016年4月

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：Wiley-VCH Verlag

Hydrogen gas (H 2) is considered to be one of the most important gases on earth
it can be used as an important alternative source of renewable energy. Although the amount of this gas in the Earth's atmosphere is far less compared to other gases, H 2 can be produced in different ways either by physical, chemical, or biological reactions, or obtained from fossil fuels. It can be produced biologically by lower or higher organisms, and this can contribute as an alternative source of H 2 for future generations. For biological H 2 production, bacteria, cyanobacteria, algae, and higher plants are the major organisms that can produce pure H 2 for sustainable usage. In this chapter, we briefly review different methods of production of H 2 and focus on modern studies devoted to photosynthetic production of H 2 by algae and microorganisms.

DOI： 10.1002/9783527674268.ch20

Polypeptide and Mn-Ca oxide: Toward a biomimetic catalyst for water-splitting systems 査読

Mohammad Mahdi Najafpour, Mohadeseh Zarei Ghobadi, Bahram Sarvi, Sepideh Madadkhani, Davood Jafarian Sedigh, Parvin Rafighi, Mojtaba Tavahodi, Jian-Ren Shen, Suleyman I. Allakhverdiev

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 41 ( 12 ) 5504 - 5512 2016年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Water oxidation is the bottleneck for hydrogen production by water-splitting systems using sunlight or other sustainable energies. Herein we report nano-sized Mn-Ca oxide in an engineered polypeptide (Glu-Glu-Glu-Glu-Glu-Glu-Glu-His-Val-Val-Val-Val-Val-Val-Val-Val) as a structural model for biological water-oxidizing site in plants, algae, and cyanobacteria. The compound was synthesized by a simple procedure and characterized by transmission electron microscopy, atomic absorption spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction spectrometry, UV-Visible spectroscopy, dynamic light scattering, and some electrochemical methods. Using hydrogen to store sustainable energies is a promising strategy in near future and such nano-sized Mn-Ca oxide/polypeptide is a promising strategy in water-splitting systems to provide cheap electrons from water toward hydrogen production. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2016.01.131

Geometric and electronic structures of the synthetic Mn4CaO4 model compound mimicking the photosynthetic oxygen-evolving complex 査読国際誌

Mitsuo Shoji, Hiroshi Isobe, Jian-Ren Shen, Kizashi Yamaguchi

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 18 ( 16 ) 11330 - 11340 2016年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Water oxidation by photosystem II (PSII) converts light energy into chemical energy with the concomitant production of molecular oxygen, both of which are indispensable for sustaining life on Earth. This reaction is catalyzed by an oxygen-evolving complex (OEC) embedded in the huge PSII complex, and its mechanism remains elusive in spite of the extensive studies of the geometric and electronic structures. In order to elucidate the water-splitting mechanism, synthetic approaches have been extensively employed to mimic the native OEC. Very recently, a synthetic complex [Mn4CaO4(ButCOO)(8)(py)(ButCOOH)(2)] (1) closely mimicking the structure of the native OEC was obtained. In this study, we extensively examined the geometric, electronic and spin structures of 1 using the density functional theory method. Our results showed that the geometric structure of 1 can be accurately reproduced by theoretical calculations, and revealed many similarities in the ground valence and spin states between 1 and the native OEC. We also revealed two different valence states in the one-electron oxidized state of 1 (corresponding to the S-2 state), which lie in the lower and higher ground spin states (S = 1/2 and S = 5/2), respectively. One remarkable difference between 1 and the native OEC is the presence of a non-negligible antiferromagnetic interaction between the Mn1 and Mn4 sites, which slightly influenced their ground spin structures (spin alignments). The major reason causing the difference can be attributed to the short Mn1-O5 and Mn1-Mn4 distances in 1. The introduction of the missing O4 atom and the reorientation of the Ca coordinating ligands improved the Mn1-O5 and Mn1-Mn4 distances comparable to the native OEC. These modifications will therefore be important for the synthesis of further advanced model complexes more closely mimicking the native OEC beyond 1.

DOI： 10.1039/c5cp07226c

Manganese Compounds as Water-Oxidizing Catalysts: From the Natural Water-Oxidizing Complex to Nanosized Manganese Oxide Structures 査読国際誌

Mohammad Mahdi Najafpour, Gernot Renger, Malgorzata Holynska, Atefeh Nemati Moghaddam, Eva-Mari Aro, Robert Carpentier, Hiroshi Nishihara, Julian J. Eaton-Rye, Jian-Ren Shen, Suleyman I. Allakhverdiev

CHEMICAL REVIEWS 116 ( 5 ) 2886 - 2936 2016年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

All cyanobacteria, algae, and plants use a similar water-oxidizing catalyst for water oxidation. This catalyst is housed in Photosystem II, a membrane-protein complex that functions as a light-driven water oxidase in oxygenic photosynthesis. Water oxidation is also an important reaction in artificial photosynthesis because it has the potential to provide cheap electrons from water for hydrogen production or for the reduction of carbon dioxide on an industrial scale. The water-oxidizing complex of Photosystem II is a Mn-Ca cluster that oxidizes water with a low overpotential and high turnover frequency number of up to 25-90 molecules of O-2 released per second. In this Review, we discuss the atomic structure of the Mn-Ca cluster of the Photosystem II water-oxidizing complex from the viewpoint that the underlying mechanism can be informative when designing artificial water-oxidizing catalysts. This is followed by consideration of functional Mn-based model complexes for water oxidation and the issue of Mn complexes decomposing to Mn oxide. We then provide a detailed assessment of the chemistry of Mn oxides by considering how their bulk and nanoscale properties contribute to their effectiveness as water-oxidizing catalysts.

DOI： 10.1021/acs.chemrev.5b00340

Novel Features of Eukaryotic Photosystem II Revealed by Its Crystal Structure Analysis from a Red Alga 査読国際誌

Hideo Ago, Hideyuki Adachi, Yasufumi Umena, Takayoshi Tashiro, Keisuke Kawakami, Nobuo Kamiya, Lirong Tian, Guangye Han, Tingyun Kuang, Zheyi Liu, Fangjun Wang, Hanfa Zou, Isao Enami, Masashi Miyano, Jian-Ren Shen

JOURNAL OF BIOLOGICAL CHEMISTRY 291 ( 11 ) 5676 - 5687 2016年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Photosystem II (PSII) catalyzes light-induced water splitting, leading to the evolution of molecular oxygen indispensible for life on the earth. The crystal structure of PSII from cyanobacteria has been solved at an atomic level, but the structure of eukaryotic PSII has not been analyzed. Because eukaryotic PSII possesses additional subunits not found in cyanobacterial PSII, it is important to solve the structure of eukaryotic PSII to elucidate their detailed functions, as well as evolutionary relationships. Here we report the structure of PSII from a red alga Cyanidium caldarium at 2.76 resolution, which revealed the structure and interaction sites of PsbQ, a unique, fourth extrinsic protein required for stabilizing the oxygen-evolving complex in the lumenal surface of PSII. The PsbQ subunit was found to be located underneath CP43 in the vicinity of PsbV, and its structure is characterized by a bundle of four up-down helices arranged in a similar way to those of cyanobacterial and higher plant PsbQ, although helices I and II of PsbQ were kinked relative to its higher plant counterpart because of its interactions with CP43. Furthermore, two novel transmembrane helices were found in the red algal PSII that are not present in cyanobacterial PSII; one of these helices may correspond to PsbW found only in eukaryotic PSII. The present results represent the first crystal structure of PSII from eukaryotic oxygenic organisms, which were discussed in comparison with the structure of cyanobacterial PSII.

DOI： 10.1074/jbc.M115.711689

CRYSTALLOGRAPHY Resolution beyond the diffraction limit 査読国際誌

Jian-Ren Shen

NATURE 530 ( 7589 ) 168 - 169 2016年2月

Chemical Equilibrium Models for the S-3 State of the Oxygen-Evolving Complex of Photosystem II 査読国際誌

Hiroshi Isobe, Mitsuo Shoji, Jian-Ren Shen, Kizashi Yamaguchi

INORGANIC CHEMISTRY 55 ( 2 ) 502 - 511 2016年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We have performed hybrid density functional theory (DFT) calculations to investigate how chemical equilibria can be described in the S-3 state of the oxygen-evolving complex in photosystem II. For a chosen 340-atom model, 1 stable and 11 metastable intermediates have been identified within the range of 13 kcal mol(1) that differ in protonation, charge, spin, and conformational states. The results imply that reversible interconversion of these intermediates gives rise to dynamic equilibria that involve processes with relocations of protons and electrons residing in the Mn4CaO5 cluster, as well as bound water ligands, with concomitant large changes in the cluster geometry. Such proton tautomerism and redox isomerism are responsible for reversible activation/deactivation processes of substrate oxygen species, through which MnO and OO bonds are transiently ruptured and formed. These results may allow for a tentative interpretation of kinetic data on substrate water exchange on the order of seconds at room temperature, as measured by time-resolved mass spectrometry. The reliability of the hybrid DFT method for the multielectron redox reaction in such an intricate system is also addressed.

DOI： 10.1021/acs.inorgchem.5b02471

The effect of lanthanum(III) and cerium(III) ions between layers of manganese oxide on water oxidation 査読国際誌

Mohammad Mahdi Najafpour, Mohsen Abbasi Isaloo, Malgorzata Holynska, Jian-Ren Shen, Suleyman Allakhverdiev

PHOTOSYNTHESIS RESEARCH 126 ( 2-3 ) 489 - 498 2015年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

Manganese oxide structure with lanthanum(III) or cerium(III) ions between the layers was synthesized by a simple method. The ratio of Mn to Ce or La in samples was 0.00, 0.04, 0.08, 0.16, 0.32, 0.5, 0.82, or 1.62. The compounds were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction studies, and atomic absorption spectroscopy. The compounds show efficient catalytic activity of water oxidation in the presence of cerium(IV) ammonium nitrate with a turnover frequency of 1.6 mmol O-2/mol Mn.s. In contrast to the water-oxidizing complex in Photosystem II, calcium(II) has no specific role to enhance the water-oxidizing activity of the layered manganese oxides and other cations can be replaced without any significant decrease in water-oxidizing activities of these layered Mn oxides. Based on this and previously reported results from oxygen evolution in the presence of H (2) (18) O, we discuss the mechanism and the important factors influencing the water-oxidizing activities of the manganese oxides.

DOI： 10.1007/s11120-015-0098-9

Special issue on Regulation of the Photosynthetic Systems in honor of Tingyun Kuang 国際誌

Congming Lu, Jian-Ren Shen, Lixin Zhang

PHOTOSYNTHESIS RESEARCH 126 ( 2-3 ) 185 - 188 2015年12月

The effect of lanthanum(III) and cerium(III) ions between layers of manganese oxide on water oxidation (vol 126, pg 489, 2015) 査読国際誌

Mohammad Mahdi Najafpour, Mohsen Abbasi Isaloo, Malgorzata Holynska, Jian-Ren Shen, Suleyman I. Allakhverdiev

PHOTOSYNTHESIS RESEARCH 126 ( 2-3 ) 499 - 499 2015年12月

Site-directed mutagenesis of amino acid residues of D1 protein interacting with phosphatidylglycerol affects the function of plastoquinone Q(B) in photosystem II 査読国際誌

Kaichiro Endo, Naoki Mizusawa, Jian-Ren Shen, Masato Yamada, Tatsuya Tomo, Hirohisa Komatsu, Masami Kobayashi, Koichi Kobayashi, Hajime Wada

PHOTOSYNTHESIS RESEARCH 126 ( 2-3 ) 385 - 397 2015年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

Recent X-ray crystallographic analysis of photosystem (PS) II at 1.9- resolution identified 20 lipid molecules in the complex, five of which are phosphatidylglycerol (PG). In this study, we mutagenized amino acid residues S232 and N234 of D1, which interact with two of the PG molecules (PG664 and PG694), by site-directed mutagenesis in Synechocystis sp. PCC 6803 to investigate the role of the interaction in PSII. The serine and asparagine residues at positions 232 and 234 from the N-terminus were mutagenized to alanine and aspartic acid, respectively, and a mutant carrying both amino acid substitutions was also produced. Although the obtained mutants, S232A, N234D, and S232AN234D, exhibited normal growth, they showed decreased photosynthetic activities and slower electron transport from Q(A) to Q(B) than the control strain. Thermoluminescence analysis suggested that this slower electron transfer in the mutants was caused by more negative redox potential of Q(B), but not in those of Q(A) and S-2. In addition, the levels of extrinsic proteins, PsbV and PsbU, were decreased in PSII monomer purified from the S232AN234D mutant, while that of Psb28 was increased. In the S232AN234D mutant, the content of PG in PSII was slightly decreased, whereas that of monogalactosyldiacylglycerol was increased compared with the control strain. These results suggest that the interactions of S232 and N234 with PG664 and PG694 are important to maintain the function of Q(B) and to stabilize the binding of extrinsic proteins to PSII.

DOI： 10.1007/s11120-015-0150-9

Proton Matrix ENDOR Studies on Ca2+-depleted and Sr2+-substituted Manganese Cluster in Photosystem II 査読国際誌

Hiroki Nagashinna, Yoshiki Nakajima, Jian-Ren Shen, Hiroyuki Mino

JOURNAL OF BIOLOGICAL CHEMISTRY 290 ( 47 ) 28166 - 28174 2015年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Proton matrix ENDOR spectra were measured for Ca2+-depleted and Sr2+-substituted photosystem II (PSII) membrane samples from spinach and core complexes from Theymosynechococcus vulcanus in the S-2 state. The ENDOR spectra obtained were similar for untreated PSII from T. vulcanus and spinach, as well as for Ca2+-containing and Sr2+-substituted PSII, indicating that the proton arrangements around the manganese cluster in cyanobacterial and higher plant PSII and Ca2+-containing and Sr2+-substituted are similar in the S-2 state, in agreement with the similarity of the crystal structure of both Ca2+-containing and Sr2+-substituted PSII in the Si state. Nevertheless, slightly different hyperfine separations were found between Ca2+-containing and Sr2+-substituted PSII because of modifications of the water protons ligating to the Sr2+ ion. Importantly, Ca2+ depletion caused the loss of ENDOR signals with a 1.36-MHz separation because of the loss of the water proton W4 connecting Ca2+ and Y, directly. With respect to the crystal structure and the functions of Ca2+ in oxygen evolution, it was concluded that the roles of Ca2+ and Sr2+ involve the maintenance of the hydrogen bond network near the Ca2+ site and electron transfer pathway to the manganese cluster.

DOI： 10.1074/jbc.M115.675496

Strong Coupling between the Hydrogen Bonding Environment and Redox Chemistry during the S-2 to S-3 Transition in the Oxygen-Evolving Complex of Photosystem II 査読国際誌

Hiroshi Isobe, Mitsuo Shoji, Jian-Ren Shen, Kizashi Yamaguchi

JOURNAL OF PHYSICAL CHEMISTRY B 119 ( 43 ) 13922 - 13933 2015年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

We have studied the early phase of the S-2 -> S-3 transition in the oxygen-evolving complex (OEC) of photosystem II using the hybrid density functional theory with a quantum mechanical model composed of 338-341 atoms. Special attention is given to the vital role of water molecules in the vicinity of the Mn4CaO5 core. Our results demonstrate how important the dynamic behavior of surrounding water molecules is in mediating critical chemical transformations such as binding and deprotonation of substrates and hydration of the catalytic site and identify a strong coupling of water-chain relocation near the redox-active tyrosine residue Tyr161 (Tyr(Z)) with oxidation of the Mn4CaO5 cluster by Tyr(Z)center dot(+). The oxidation reaction is further promoted when the catalytic site is more solvated by water. These results indicate the importance of surrounding water molecules in biological catalysts as they ultimately lead to effective catalytic function and/or favorable electron-transfer dynamics.

DOI： 10.1021/acs.jpcb.5b05740

The biological water-oxidizing complex at the nano-bio interface 査読国際誌

Mohammad Mahdi Najafpour, Mohadeseh Zarei Ghobadi, Anthony W. Larkum, Jian-Ren Shen, Suleyman I. Alliakhverdiev

TRENDS IN PLANT SCIENCE 20 ( 9 ) 559 - 568 2015年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE LONDON

Photosynthesis is one of the most important processes on our planet, providing food and oxygen for the majority of living organisms on Earth. Over the past 30 years scientists have made great strides in understanding the central photosynthetic process of oxygenic photosynthesis, whereby water is used to provide the hydrogen and reducing equivalents vital to CO2 reduction and sugar formation. A recent crystal structure at 1.9-1.95 angstrom has made possible an unparalleled map of the structure of photosystem II (PSII) and particularly the manganese-calcium (Mn-Ca) cluster, which is responsible for splitting water. Here we review how knowledge of the water-splitting site provides important criteria for the design of artificial Mn-based water-oxidizing catalysts, allowing the development of clean and sustainable solar energy technologies.

DOI： 10.1016/j.tplants.2015.06.005

High-resolution native structure analyses of supramacromolecular complexes susceptible to radiation damage 査読

Hideo Ago, Kunio Hirata, Go Ueno, Masaki Yamamoto, Kyoko Shinzawa-Itoh, Tomitake Tsukihara, Shinya Yoshikawa, Michihiro Suga, Fusamichi Akita, Jian-Ren Shen

Acta Crystallographica Section A Foundations and Advances 71 ( a1 ) s15 - s15 2015年8月

On the guiding principles for lucid understanding of the damage-free S-1 structure of the CaMn4O5 cluster in the oxygen evolving complex of photosystem II 査読

Mitsuo Shoji, Hiroshi Isobe, Shusuke Yamanaka, Michihiro Suga, Fusamichi Akita, Jian-Ren Shen, Kizashi Yamaguchi

CHEMICAL PHYSICS LETTERS 627 44 - 52 2015年5月

記述言語：英語出版者・発行元：ELSEVIER

Several key concepts and geometrical rules for the Mn-Mn and Mn-O distances of the CaMn4O5 cluster in the oxygen evolving complex (OEC) of photosystem II (PSII) by previous and present theoretical calculations were examined for a clear understanding of the damage-free Si structure revealed by X-ray free electron laser (XFEL). A simple equation to estimate the Mn-a-Mn-b distance in relation to the Mn-a-O(5) distance was derived taking into consideration the Jahn-Teller (JT) effects for Mn centers, indicating that the XFEL structure is regarded as a slightly right-elongated quasi-central structure in contradiction to a right-opened structure proposed by the EXAFS measurements. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2015.03.033

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