| Project/Area Number |
06640848
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物生理
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
KOIKE Hiroyuki Himeji Inst.Tech., Dept.Life Science, Associate Professor, 理学部, 助教授 (60201480)
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| Co-Investigator(Kenkyū-buntansha) |
KASHINO Yasuhiro same as above, Research Associate, 理学部, 助手 (20221872)
SATOH Kazuhiko same as above, Professor, 理学部, 教授 (00090522)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1994: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Cytochrome b6 / f complex / thermophilic cyanobacterium / thylakoid membranes / heptylthioglucoside / duroquinone / plastoquinone |
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| Research Abstract |
Cytochrome b6/f complex accepts electrons from plastoquinol which was reduced by photosystem II.The complex transfers electrons to photosystem I and forms H^+ gradient across the thylakoid membranes to form ATP simultaneously. In this research project, we have purified the complex from thylakoid membranes of a cyanobacterium focussing on development of simple purification procedure and its high yield. We also have investigated the substrate (quinone) specificity of the complex and estimated the structure of active site of the quinone binding pocket.
The complex was purified from a thermophilic cyanobacterium, Synechococcus vulcanus. We have improved on the existing procedure by the following two points : 1) thylakoid membranes were sonicated simultaneously during NaBr treatment to remove all the extrinsic proteins and 2) deoxycholate was added together with heptylthioglucoside to solubilize the complex. By this improvement, the complex was effectively precipitated in a narrow range of ammonium sulfate concentration and could be purified further.
Tetramethyl-p-benzoquinone is normally used for activity measurement. Trimethyl-p-benzoquinone was found to be effective as well. Dimethyl-p-benzoquinones or dichloro-p-benzoquinones (DCBQ) were, however, not avtive as electron donor to the complex. Judging from the fact that DCBQ is the most effective electron acceptor for photosystem II,the structure of quinone binding pocket of b6/f complex is rather different from that of Q_B site of photosystem II.
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