Characterization of dynamic processes in proteins by combining solid- and solutionstate NMR spectroscopy

应用研究项目的目标是结合溶液和MAS固态核磁共振光谱对蛋白质的动态过程进行综合分析。两个申请小组的综合专业知识对拟议的项目至关重要。蛋白质动力学是理解生物功能的关键因素。核磁共振弛豫实验允许表征这些动态过程。溶液中的弛豫是由分子的整体翻滚控制的（10-9秒）。因此，只有快速运动过程（10-12-10-9 s）可以用解态弛豫实验来探测。时间尺度10-9-10-7 s上的运动很难或不可能通过溶液态弛豫测量来检测。使用剩余偶极耦合的替代方法仍在讨论中。在本提案中，我们建议结合溶液和MAS固态核磁共振数据来探测这些动态过程。我们试图确定内部运动是否在从溶液转变为固体时发生了变化。虽然存在大量证据表明动态行为是相似的，但光谱背景，另一方面，是非常不同的：固态核磁共振光谱对广泛的相关时间范围敏感，而溶液态核磁共振实验是选择性的，相对于更快的运动形式。这为蛋白质内部动力学的详细和独立表征开辟了有吸引力的可能性。拟议的工作将弥合现有的“时间尺度差距”，并扩展核磁共振动力学研究的边界。在拟议的研究中，固态实验将由Bernd Reif （BR）小组进行，而溶液工作则由Nikolai Skrynnikov （NS）小组负责。数据分析将共同进行。

The goal of the applied research project is an integrated analysis of dynamic processes in proteins combining solution and MAS solid-state NMR spectroscopy. The combined expertise of the two applying groups is essential for the proposed project. Protein dynamics is a key element for understanding of biological function. Nuclear magnetic resonance relaxation experiments allow the characterization of these dynamic processes. Relaxation in solution is controlled by the overall tumbling of the molecule (10-9 s). Only fast motional processes (10-12-10-9 s) can be therefore probed using solution-state relaxation experiments. Motions on the time scale 10-9-10-7 s are difficult or impossible to detect by solution-state relaxation measurements. Alternative approaches using residual dipolar couplings remain under discussion. In this proposal, we suggest to combine solution- and MAS solid-state NMR data to probe these dynamic processes. We seek to determine if internal motions are changed upon transition from solution to solids. While substantial evidences exist that the dynamic behavior is similar, the spectroscopic context, on the other hand, is very different: solid-state NMR spectroscopy is sensitive to a broad range of correlation times, while solution-state NMR experiments are selective with respect to faster forms of motion. This opens up attractive possibilities for a detailed and selfcontained characterization of internal protein dynamics. The proposed work will bridge the existing ‘time-scale gap’ and extend the boundaries of dynamics studies by NMR. In the proposed study, solid-state experiments will be conducted by the group of Bernd Reif (BR), while solution work is the responsibility of Nikolai Skrynnikov’s (NS) group. The data analysis will be carried out jointly.