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的无弹性中子散射在宽的能量范围内。到目前为止，获得的光谱是最准确的，并且报告的光谱是最精确的。定性地用SNase的正常模式分析的结果对观察到的25K处观察到的光谱进行了解释，并将观察到的峰分配给理论振动模式。但是，实验与理论计算之间的定量一致性是如此差，以至于需要改善用于计算的潜在功能。还通过分子动力学模拟的结果对在室温下获得的光谱进行了定性解释。在揭示折叠状态，非弹性和准中子中子散射实验（折叠）（折叠）和截断的SNase（已折叠酶）的动态特性（未折叠）。在室温下观察到明显的差异，并具有高度水合的样本，表明折叠状态的特异性运动是一种非谐的运动，该运动用玻璃峰上方的水激活。研究了玻色子峰的起源或在低温下研究蛋白质的低能量激发。我们发现玻色子峰位置显示出明显的分子量依赖性。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，而是整个分子上的延长运动。这种特性可能是包括蛋白质在内的软物质的常见。开发了评估具有非弹性中子散射的蛋白质动力学的不homemenity的方法。对于细菌紫红素，讨论了与其功能有关的这种不植物。使用氘标记，玻璃过渡温度在蛋白质中的位点之间变化。建议这种不作原理对蛋白质功能很重要。