Experimental and Theoretical Studies on Protein Dynamics and Changes in Dynamics upon Folding

蛋白质动力学和折叠时动力学变化的实验和理论研究

基本信息

批准号：
09044220
负责人：
KATAOKA Mikio
金额：
$ 4.42万
依托单位：
Nara Institute of Science and Technology (1998-1999)Osaka University (1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

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.

在 25K 和室温下，观察到葡萄球菌核酸酶在宽能量范围内的非弹性中子散射。所获得的光谱是迄今为止报道的最准确和最精细的光谱。用 SNase 的简正模式分析结果定性地解释了 25K 处观察到的光谱，并将观察到的峰分配给理论振动模式。然而，实验与理论计算之间的定量一致性非常差，因此需要改进用于计算的势函数。室温下获得的光谱也用分子动力学模拟的结果进行了定性解释。为了揭示折叠态特有的动力学特性，对野生型SNase（折叠）和截短型SNase进行了非弹性和准弹性中子散射实验。 SNase（展开）。在室温下观察到高度水合样品的明显差异，表明折叠状态的特定运动是非简谐运动，该运动在玻璃化转变之上被水激活。玻色子峰的起源或低温下的低能量激发对蛋白质进行了研究。我们发现玻色子峰位置表现出显着的分子量依赖性。这一事实表明，玻色子峰的起源不是二级结构元素的局部运动，而是整个分子的扩展运动。这种性质对于包括蛋白质在内的软物质可能是常见的。开发了用非弹性中子散射评估蛋白质动力学不均匀性的方法。对于细菌视紫红质，讨论了这种不均匀性与其功能的关系。使用氘标记，玻璃化转变温度随蛋白质位点的不同而变化。有人认为这种不均匀性对于蛋白质功能很重要。