| Project/Area Number |
09558092
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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 | 展開研究 |
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| Research Field |
Biophysics
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KIDERA Akinori Grad. Sch. Sci, KYOTO UNIVERSITY, Assistant Professor, 大学院・理学研究科, 助教授 (00186280)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIDA Masahisa JEOL Ltd. Div. Electron Optics Instruments, Chief Director, 電子工学機器技術本部, 本部長
MITSUOKA Kaoru Grad. Sch. Sci, KYOTO UNIVERSITY, Assistant, 大学院・理学研究科, 助手 (60301230)
FUJIYOSHI Yoshinori Grad. Sch. Sci, KYOTO UNIVERSITY, Professor, 大学院・理学研究科, 教授 (80142298)
HIRAI Teruhisa Matsushita Electric Industrial Co. Ltd. IIAR, Senior Res. Assistant, 国際研究所, シニアリサーチアシスタント (10450412)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 1999: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1997: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Electron Crystallography / Electron Diffraction / Electron Microscope / Software / Bacteriorhodopsin / Atomic Scattering Factor / Refinement / Protein / ソフトウエアー |
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| Research Abstract |
3D Structure determination of membrane bound proteins by electron diffraction from 2D crystal has a crucial importance in structural biology as a complementary method to X-ray diffraction. The purpose of this work is to develop a modeling and refinement tool for the electron crystallography. Through the research period, we have determined 3D structures of various proteins, and established the modeling and refinement techniques. The results of the technical development can be seen in the atomic resolution models of bacteriorhodopsin and aquaporin, which provide important pieces of information about the mechanism how their functions occur on the 3D structures. It has become clear from the analyses that the most fundamental characteristics in electron diffraction is in the information about the charged state of a protein. Electron is scattered by the electronic potential instead of electron density in X-ray scattering. Hence, the valence electron strongly affects the scattering behavior of electron. In other words, the electron diffraction depends on the charged state of the constituent atoms. We developed a method of treating charged state correctly by the following way. We carred out ab initio quantum chemical calculations of the electronic potentials of small model compounds, which constitute a protein molecule, in various charged states and solvation states, and calculated the atomic scattering factor for each charged and solvation state by the Fourier transformation of the potential function. In the application to the structural analysis, since the charge state has a certain distribution in a crystal, an optimal linear combination of the atomic scattering factors for various charge states will be calculated in the course of the refinement process.
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