| Project/Area Number |
11660061
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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 |
Plant nutrition/Soil science
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
MATOH Toru Graduate School of Agriculture, Associate Professor, 農学研究科, 助教授 (50157393)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | Boron / Cell wall / Calcium / Pectin methyl esterase / Cultured tobacco cells / Pectic polysaccharide / ラムノガラクツロナンII / 必須元素 |
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| Research Abstract |
We have revealed that the essential plant nutrient element boron (B) works to cross-link pectic polysaccharide chains at the rhamnogalacturonan II (RG-II) sites along the chain. In the cross-link, Ca^<2+> ions are also involved to connect the chains. Ca^<2+> are considered to bind ionically with the carboxyl groups of polygalacturonic acids. Polygalacturonic acids are secreted through Golgi vesicles as in a methyl-esterified form. In cell walls after secretion, the methyl moiety is hydrolyzed with pectin methyl esterase (PME) to prodtuce free carboxylic group. In this study, I have concentrated on the PME of various plant sources.
PME enzymes are all localized in cell walls of cultured tobacco cells, pea stems and carrot roots. They are comprised of several isoenzymes. In tobacco cells, nearly all the enzymes are basic in the isoelectric point (IP), on the other hand 70% of the carrot enzymes are neutral in IP.All the PME enzymes need Ca^<2+> for their activities, and the Km values for Ca^<2+> were calculated to be 3 mM.Boron did not activate the enzyme. One of the basic isoenzymes of tobacco is now under purification.
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