Mixed-valence state of oxygen-evolving complex in photosynthetic photosystem II
| Project/Area Number |
17H03645
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | Osaka City University |
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Principal Investigator |
Kamiya Nobuo 大阪市立大学, 複合先端研究機構, 名誉教授 (60152865)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000)
Fiscal Year 2019: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2018: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2017: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
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| Keywords | 光化学系II / 光合成 / 水分解酸素発生 / 金属クラスター / 混合原子価状態 / SPring-8 / 金剛原子価 / タンパク質 / X線結晶構造解析 / 蛋白質 / 混合原子価 / 水分解 / 酸素発生 |
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| Outline of Final Research Achievements |
Photosystem II (PSII) progresses the first reaction of photosynthesis, in which the oxygen-evolving complex (Mn4Ca cluster) splits two water molecules and produces one molecular oxygen. By crystal structure analyses of PSII utilizing anomalous dispersion effect of Mn atoms, valence distributions of the four Mn atoms denoted from Mn1 to Mn4 in the Mn4Ca clusters were established. The results showed that Mn1 altered it valence number as III and II for two PSII monomers in a crystallographic asymmetric unit. Based on the new knowledge obtained for the S1 and S0 states of the Kok cycle model, changes in redox potential were presumed for the hole oxygen-evolving reaction, and a reaction mechanism of PSII was newly proposed.
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| Academic Significance and Societal Importance of the Research Achievements |
光合成は、二酸化炭素と水から、地球上のほとんど全ての生物が生きるための糧となる炭水化物と酸素を提供している。光化学II（PSII）は、光合成の初発過程を担い、また光合成反応の半分にあたる水分解・酸素発生反応を触媒している酵素である。その反応機構の解明には、光合成の本質に迫る学術的な意義と共に、現在の我々にとって喫緊の課題となっている環境問題や将来の食料問題を解決するための基礎知識となる点で大きな社会的な意義も持っている。
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Report
(4 results)
Research Products
(35 results)
