1999 Fiscal Year Final Research Report Summary
Study on the Alteration of Catalytic Activities by the Change of Three Dimensional Structure of Enzyme Proteins
| Project/Area Number |
10680564
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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 |
Bioorganic chemistry
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| Research Institution | Toyama Medical & Pharmaceutical University |
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Principal Investigator |
SANKAWA Ushio Toyama Medical & Pharmaceutical University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (60012613)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Toshimitsu Toyama Medical & Pharmaceutical University, Faculty of Pharmaceutical Sciences, Assciate Professor, 薬学部, 助教授 (40092796)
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| Project Period (FY) |
1998 – 1999
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| Keywords | chalcone synthase / stilbene synthase / cross reaction / polyketide / Psilotum nodum / point mutation |
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| Research Abstract |
Chalcone synthase (CHS) is the representative polyketide synthase of plant origin, which catalyzes the first reaction of flavonoid biosynthesis to form its basic skeleton. CHSs are ubiquitously present in plants and play essential physiological role to protect plants from outer stresses. The other polyketide synthases relating to chalcone synthase have a high homology and called chalcone synthase superfamily. The reaction CHS is very similar to fatty acid synthase (FAS), however its unique enzyme reaction is the direct condensation of malonyl CoA with decarboxylation in contrast to ACP malonyl CoA in FAS. Small molecular weight of CHS (ca. 43KD) is the most attractive point of study. 1. Heterologous expression sytems with E. coli, yeast and vaculovirus were established to obtain Chess in a large amount and reactions of CHIS obtained by different expression systems were investigated in details. 2. We first demonstrate that chalcone and stilbene synthases showed cross reactions, that is the two enzyme produced counter part enzyme products as by products. The degree of cross reaction was decreased when the enzymes were expressed in eukaryote systems. 3. Psilotum nodum is the most primitive vascular plant which produces phnylpyrone. Five clones of CHIS superfamily were obtained and their reaction was characterized. In addition to CHIS, two STS and isovalerophenone synthase it contains unfunctional CHIS family mRNA. Essential histidine in polyketide synthase is replaced with glutamine and revertant, mutated glutamine to histidine as in CHIS and STS did not show any significant reaction of polyketide synthase. The lack of enzyme activity is due to the change of whole three dimentional structure which is affected by the alteration of other amino acids.
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Research Products
(14 results)
