| Project/Area Number |
09044220
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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 | Nara Institute of Science and Technology (1998-1999)
Osaka University (1997) |
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Principal Investigator |
KATAOKA Mikio Nara Institute of Science and Technology, Graduate School of Materials Science, Professor, 物質創成科学研究科, 教授 (30150254)
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| Co-Investigator(Kenkyū-buntansha) |
GO Nobuhiro Kyoto Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (50011549)
KAMIKUBO Hironari High Energy Accelerator Res. Org., Inst. Materials Struct. Sci., Research Associate, 物質構造科学研究所, 助手 (20311128)
TOKUNAGA Fumio Osaka Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (80025452)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Protein Dynamics / Protein Folding / Inelastic Neutron Scattering / Quasielastic Neutron Scattering / Normal Mode Analysis / Molecular Dynamics Simulation / Staphylococcal Nuclease / Boson Peak |
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| Research Abstract |
Inelastic neutron scattering over wide energy range was observed for staphylococcal nuclease at 25K and at room temperature. The obtained spectra were the most accurate and the finest reported so far. The observed spectrum at 25K was explained qualitatively with the results of the normal mode analysis for SNase, and the observed peaks were assigned to the theoretical vibrational modes. However, the quantitative agreement between the experiment and the theoretical calculation was so poor that the improvements in potential functions used for the calculation should be required. The obtained spectrum at room temperature was also qualitatively explained with the results of the molecular dynamics simulation.
In order to reveal dynamic properties specific to the folded state, inelastic and quasielastic neutron scattering experiments were performed for the wild type SNase (folded) and the truncated SNase (unfolded). The apparent differences were observed at room temperature with highly hydrated specimens, indicating that the specific motions to the folded state is the anharmonic motion which is activated with water above the glass transition.
The origin of the boson peak or low energy excitation at low temperature for proteins was investigated. We found that the boson peak position shows significant molecular weight dependency. This fact suggests that the origin of boson peak is not the localized motion to the secondary structure element, but the extended motion over the whole molecule. This property may be common for soft matters including proteins.
The method to evaluate inhomogenity of protein dynamics with inelastic neutron scattering was developed. For bacteriorhodopsin, such inhoogenities were discussed in relation to its function. Using deuterium labeling, glass transition temperature varies from site to site in protein. It is suggested that such inhomogenities are important for the protein function.
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