| Project/Area Number |
16310152
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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 |
Living organism molecular science
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| Research Institution | Kyoto University |
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Principal Investigator |
HIRATAKE Jun Kyoto University, Institute for Chemical Research, Associate Professor, 化学研究所, 助教授 (80199075)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUTANI Masaharu Kyoto University, Institute for Chemical Research, Assistant Professor, 化学研究所, 助手 (60303898)
SHIMIZU Bun'ichi Kyoto University, Institute for Chemical Research, Assistant Professor, 化学研究所, 助手 (50324695)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,800,000 (Direct Cost: ¥15,800,000)
Fiscal Year 2006: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2004: ¥8,300,000 (Direct Cost: ¥8,300,000)
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| Keywords | β-glycosylamidines / β-glycosidase inhibitor / substrate analogues / glycon substrate specificity / plant glycosidases / affinity chromatography / diglycoside-specific glycosidases / X-ray crystal structure analysis / 基質アナログリガンド / 二糖配糖体認識機構 / 静電的相互作用 / アフィニティーリガンド / family 20 β-N-acetylglucosaminidase / 中間体アナログ |
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| Research Abstract |
The function and the physiological roles of plant β-glycosidases have been studied by using p-glycosylamidines as molecular probes. p-Glycosylamidines, newly developed p-glycosidase inhibitors that selectively inhibitβ-glycosidases according to their glycon substrate specificities, have been successfully used as ligand for affinity chromatography of glycosidases. High fidelities of β-glycosylamidines as specific binders toward theβ-glycosidases with the corresponding glycon substrate specificities enabled one-step affinity purification of specific β-glycosidases from natural samples according to their glycon substrate specificities as a sole marker. This method has been successfully used for the isolation of diglycoside-specific p-glycosidases from microbes and a p-N-acetylhexosaminidase from insect cells. The latter glycosidase is a key biosynthetic enzyme in processing insect-cell-specific N-glycans. With this research tool in hands, we have purified and characterized diglycoside-spe
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cific β-glycosidases (diglycosidases) from plants. The diglycosidases are thought to play a key role in self-defense system in plants by emitting defense chemicals such as linalool, 2-phenylethanol and mandelonitrile by cleaving their precursor diglycosides. β-Primeverosidase (PD), a typical diglycosidase found in tea leaves, has been purified to homogeneity by a newly developed pH-controlled affinity chromatography with p-primeverosylamidline as an affinity ligand. The enzymatic properties of PD and the binding mechanism of the β-primeverosylamidine inhibitor have been studied extensively. Furthermore, a gene encoding PD was cloned from tea leaves and was analyzed to find that the diglycosidases were a member of family 1 glycoside hydrolase with significant sequence similarities to the β-glucosidases in this family. This result suggests that plant diglycosidases have been evolved from family 1 β-glucosidases for cleavage of specific diglycosides and serve as a key enzyme in plant self-defense system. The recombinant PD was expressed and highly purified by the affinity chromatography for X-ray structural analysis. The high resolution X-ray crystal structure (1.8 Å) of PD in complex with the β-primeverosylamidine inhibitor revealed the amino acid residues recognizing the β-xylosyl moiety of β-primeveroside and the unique binding mode of β-primeverosylamidine ligand in the active site. These results cogently suggested the structural basis for their unique substrate specificities and the evolutional link between plant diglycosidases and family 1 p-glucosidases. Less
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