X-RAY AND NEUTRON SCATTERING STUDIES OF COLLECTIVE MOTIONS IN PROTEINS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 蛋白质在水溶液中经历结构波动，这似乎对 功能繁多。尽管核磁共振和X射线结晶学研究已经教会了我们很多关于侧链原子的小的、快速的、局部的运动，但更大规模的呼吸运动仍然没有得到很好的描述。这项建议涉及一系列协调的X射线和中子散射实验，旨在从尺度和动力学的角度描述蛋白质在溶液中的呼吸运动；确定溶剂成分和温度对这些运动的影响；并展示分子拥挤如何影响这些运动。我们发现了一种浓度依赖关系，它反映了相对较大的结构波动，其幅度随着浓度的降低而增加。协调的WAXS和非弹性中子散射实验将在我们小组获得大量初步数据的结构良好的蛋白质上进行。WAXS数据将在APS在多种温度下的广泛浓度范围内收集，数据根据蛋白质中发生的结构波动进行建模。NIST/ILL将收集相同蛋白质的中子自旋回波数据。来自WAXS/SANS实验的数据将根据蛋白质内二级结构的动态运动进行关联、解释和建模。将设计更多的X射线和中子实验，以支持和进一步提高所收集的中子数据的价值。这些研究的结果应该提供有关蛋白质在溶液中大规模相关运动的详细信息。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Proteins undergo structural fluctuations in aqueous solution that appear to be critical for many functions. Although NMR and x-ray crystallographic studies have taught us a great deal about small, fast, local motions of the side chain atoms, the larger scale breathing motions remain poorly characterized. This proposal involves a set of coordinated x-ray and neutron scattering experiments designed to characterize breathing motions of proteins in solution in terms if both scale and dynamics; determine the effect of solvent constituents and temperature on those motions; and demonstrate how molecular crowding impacts those motions. We have discovered a concentration- dependence that reflects relatively large scale structural fluctuations that increase in magnitude with decreasing concentration. Coordinated WAXS and inelastic neutron scattering experiments will be carried out on structurally well characterized proteins for which our group has obtained a large body of preliminary data. WAXS data will be collected at the APS over a wide concentration range at multiple temperatures, with data modeled in terms of the structural fluctuations that are occurring in the protein. Neutron spin-echo data will be collected at NIST/ILL for the same proteins. Data from WAXS/SANS experiments will be correlated, interpreted and modeled in terms of the dynamic motion of secondary structures within the proteins. Additional x-ray and neutron experiments will be designed to support and further enhance the value of the neutron data collected. The results of these studies should provide detailed information on the large-scale, correlated motions of proteins in solution.