1998 Fiscal Year Final Research Report Summary
Cooperative Study on Porphyrin Metabolism & Its Regulation
| Project/Area Number |
08045060
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Field |
植物保護
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| Research Institution | Faculty of Agriculture, Tamagawa University |
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Principal Investigator |
WAKABAYASHI Ko Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (00220830)
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| Co-Investigator(Kenkyū-buntansha) |
KOHNO Hitoshi Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (40074356)
SATO Yukiharu Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (40119516)
BRASS Sussane Faculty of Biology, Konstanz University, Lecturer, 生物学部, 講師
NICOLAUS Beate Faculty of Biology, Konstanz University, Assistant professor, 生物学部, 助教授
BOGER Peter Faculty of Biology, Konstanz University, Professor, 生物学部, 教授
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| Project Period (FY) |
1996 – 1998
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| Keywords | Protoporphyrinogen-IX oxidase (Protox) / Peroxidizing phytotoxicities / Active oxygen / Destruction of thylakoid membranes / HPLC-Isoluminol chemiluminescence / Protox inhibitors / Molecular design of Protox inhibitors |
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| Research Abstract |
Phytotoxic diphenyl ethers and cyclic imides induce inhibition of chlorophyll biosynthesis and photooxidative destruction of plant membranes affecting photosynthetic pigment contents. A peroxidizing mechanism of action of the compounds has been proposed already in our precedent study before staring this Grant-In-Aid Research. The immediate physiological response of plants against the peroxidizing compounds is a halt of chlorophyll biosynthesis in chioroplasts by specific inhibition of protoporphyrinogen-IX oxidase. This inhibition is accompanied by an abnormal accumulation of tetrapyrroles. Protoporphyrin-IX, the main tetrapyrrole intermediate accumulated, acts as a photosensitizer in the light and induces radical formation with subsequent destruction of cellular constituents. Decrease of photosynthetic pigments, chlorophylls and carotenoids, quite well correlatesproto porphyrinogen-IX oxidase inhibition by the peroxidizing compounds as well as ethane formation caused by destrucion of thylakoid membranes. This research was conducted to establish and confirm radical reactions involved in active oxygen, to elucidate oxidative destruction of thylakoid membranes.
Results obtained (1-5) are quite useful plant growth regulation, hydrogen production using green algae, and molecular design of medicine controlling active oxygen. (1) In peroxidizing reaction, lipid hydroperoxides were determined using HPLC-System combined with isoluminol-chemiluminescence, thus confirming radical reactions in the process. (2) Photosynthetic electron transport inhibitors alleviated ethane formation. (3) Peroxidizing process proceeds generally in chloroplasts to destroy thylakoid membranes. (4) Through QSAR study of the peroxidizers, newer strong peroxidizers was successfully designed and synthesized. (5) A hydrogen production process using peroxidizer and photosynthetic electron transport inhibitor was proposed.
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