| Project/Area Number |
61430010
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
天然物有機化学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SUGA Takayuki Hiroshima Univ., Science, Professor, 理学部, 教授 (00033811)
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| Co-Investigator(Kenkyū-buntansha) |
AOKI Tadashi Suzugamine Women's College, Professor, 教授 (40112164)
OTA Shinji Hiroshima Univ., Education, Lecturer, 学校教育学部, 講師 (60185270)
IZUMI Shunsuke Hiroshima Univ., Science, Assistant, 理学部, 助手 (90203116)
MUNESADA Kiyotaka Hiroshima Univ., Science, Assistant, 理学部, 助手 (30166235)
HIRATA Toshifumi Hiroshima Univ., Science, Assistant Professor, 理学部, 助教授 (80033926)
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| Project Period (FY) |
1986 – 1989
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| Keywords | Isoprenoid biosynthesis / Prenylation / Cyclization / Stereochemistry / Mechanism / Higher plants / Intermediate / Enzymology |
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| Research Abstract |
The stereochemistry and mechanism for the fundamental processes, especially prenylation and cyclization of the allylic chain, in the biosynthesis of isoprenoids were investigated as follows:
(1) "Geranyl diphosphate synthase" responsible for the prenylation between dimethylallyl diphosphate and isopentenyl diphosphate was first isolated from the leaves of Pelargonium roseum.
(2) "Polyprenyl diphosphate synthasell was partially purified from the leaves of Mallotus japonicus.
(3) Three novel polyprenols, possessing a phytyl residue, four to six internal (Z)-prenyl residues, and a Z a-terminal residue aligned in that order, were isolated from the leaves of soybean, Glycine max.
(4) ^<13>C NMR studies on the enzymatic reaction of geranyl diphosphate and isopentenyl diphosphate indicated that the prenylation involves "stepwise mechanism" via allylic cation as an intermediate.
(5) "Limonene synthasell responsible for the cyclization of geranyl diphosphate (GPP) to limonene was partially purified from the leaves of Mentha spicata and Citrus unshiu.
(6) Divalent metal cations, especially Mg^<2+> and Mn^<2+>, is essential for the enzymatic cyclization of GPP; the metal cation binds to the diphosphate moiety of GPP in a mole ratio of 1:1 in the initial stages of the cyclization and the chelation weakens the C_-O bond of the diphosphate to facilitate the elimination of the diphosphate group.
(7) The process for the cyclization involves the geranyl cation having anti- endo conformer under the steric control characteristic of the enzyme in the respective plants and then the allylic cation is led to the formation of the stereospecifically featured cyclic monoterpenoids.
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