| Project/Area Number |
09480180
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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 |
Biophysics
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
YASUOKA Noritake Himeji Institute of Technology, Professor, 理学部, 教授 (40029054)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Naoki Himeji Institute of Technology, Assistant, 理学部, 助手 (30295753)
MORIMOTO Yukio Himeji Institute of Technology, Assistant Professor, 理学部, 助教授 (80200450)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥12,200,000 (Direct Cost: ¥12,200,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1997: ¥9,400,000 (Direct Cost: ¥9,400,000)
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| Keywords | vitamin B12 enzyme / X-ray structure analysis / propanediol / diol dehydratase / synchrotron radiation / potassium ion / cyanocobalamin / TIM barrel / ビタミンB12酵素 / 放射光 / ビタミンB12 / ジオールデヒドラーゼ / 低温X線回折 / 膜タンパク質複合体 |
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| Research Abstract |
Two crystal forms of Klebsiella oxytoca diol dehydratase complexed with cyanocobalamin have been obtained and crystallographic structure analysis have been performed. The crystals belong to two different space groups, according to the corresponding crystallization condition. One crystal (form I) belongs to the space group P2_12_12_1 with unit cell dimensions of a=76.2, b=122.3, c=209.6 Å, and diffracts up to 2.2Å resolution using an X-ray beam from a synchrotron radiation source. The other crystal (form II) belongs to the space group P2_1 with unit cell dimensions of a=75.4, b=132.7, c=298.8Å, β=91.9° and diffracts up to 3.0Å resolution. The three-dimensional structure of form I was determined at 2.2Å resolution. Diol dehydratase exists in a dimeric form of hetero-trimer, (αβγ)_2. The B_<12> molecule is bound between the α and β subunits in the "base-on" mode, that is, 5,6-dimethylbenzimidazole of the nucleotide moiety is coordinated to the cobalt atom in the lower axial position. The α subunit includes a (β/α)_8 barrel. The substrate and an essential potassium ion exist deeply buried inside the barrel. Based on unique direct interactions between potassium ion and two hydroxyl groups of the substrate, propanediol, direct participation of a potassium ion in enzyme catalysis is proposed.
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