| Project/Area Number |
09640783
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理
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| Research Institution | The Institute of Physical and Chemical Research (RIKEN) |
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Principal Investigator |
ONO Taka-aki RIKEN,Laboratory for Photo-Biology, Team Leader, 光生物研究チーム, チームリーダー(研究職) (10175268)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Photosynthesis / D1-protein / photoinhibition / herbicide / photosystem II / EPR / oxygen evolution / Mn cluster / 光化学系II阻害剤 / 光損傷 / 酸素発生 / マンガンイオン / D1蛋白質 / 光阻害 / 系II酸化側 / チロシンラジカル |
|---|
| Research Abstract |
1) Various types of derivatives of phloroglucinol were synthesized in order to investigate the structure/function relationship on the D1 protein breakage activity. For the activity, OH-group at positions 2,4,6 on phenol ring is essential. Derivatives without a bulky hydrophobic side chain at position 3 showed very weak activity, indicating that the bulky group is also required for the activity. A derivative (G63) that has not nitro group at position 3 but has substituted group at position 6 has a unique activity that breaks the D1 protein to produce the same fragments as those found by photoinhibitory illumination. 2) Illumination of Ca-depleted PS II membranes sample retaining an abnormal S_2-state generated two EPR signals at g =2 region. One signal was ascribed to dipole interaction between a radical pair, and the other signal was ascribed to interaction between a radical and the Mn-cluster. A new high-spin EPR signal was detected when the latter signal was produced. 3) Spin-exchange structures of the S_2-state Mn-cluster were numerically evaluated. The calculation was performed by taking into account the magnetic properties of the S_2 multiline signal and the effective hyperfine constants determined by simulating oriented multiline spectrum. 4) Binding of Mn^<2+> to Mn-depleted PS II and electron donation from the bound Mn^<2+> to an oxidized Y_Z tyrosine were studied, and found that Mn-depleted membranes have only one unique binding site which has high affinity and high specificity for Mn^<2+>, and that Mn^<2+> bound to this site can be deliver an electron to Y_Z^+ with high efficiency.
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