Structure and Dynamics of Proteins from NMR Orientational Data

这项工作的总体目标是探索溶液中蛋白质结构和动力学的潜在新信息来源。这些新信息来自于最近在高各向异性磁化率分子的核磁共振波谱中发现的残留偶极耦合，当这些分子被放置在非常高的磁场中。这些贡献取决于连接原子核的矢量相对于分子磁化率张量轴的方向。因此，测量可以通过限制大分子远程部分的方向来提供结构信息，而现有的基于NOE的距离约束是无法实现的。这些耦合也会受到情绪平均的影响。这一点尤其重要，因为对平均过程有贡献的运动范围比对通常测量的核磁共振弛豫参数有贡献的运动范围大得多。因此，实验可以让我们深入了解那些最有可能对蛋白质功能有贡献的大振幅、慢速运动。设计和测试剩余偶极耦合的测量和分析方法是本研究的主要目的。选择两种顺磁性蛋白肌红蛋白和细胞色素b5作为初步应用的靶标。两者都具有良好的结构特征，应作为新的结构战略的适当基准。然而，关于情感对功能的影响，两者也一直是争论的主题。开发和应用于这些蛋白质的方法应该有助于解决这一争论。＊＊＊

9726341 Prestegard The overall objective of this work is to explore a potential new source of information on protein structure and dynamics in solution. The new information comes from residual dipolar couplings recently seen in NMR spectra of molecules with highly anisotropic magnetic susceptibilities when these molecules are placed in very high magnetic fields. The contributions are dependent on the orientation of the vector connecting the nuclei relative to the axes of a molecular susceptibility tensor. Measurement, thus, can provide structural information by constraining orientations of remote parts of large molecules in ways that are inaccessible using existing NOE based distance constraints. The couplings are also subject to the effects of motional averaging. This is particularly important because the range of motions contributing to the averaging process is much larger than those contributing to commonly measured NMR relaxation parameters. Experiments may, therefore, give insight into large amplitude, slower, motions that are among those most likely to contribute to protein function. Devising and testing methods for measurement and analysis of residual dipolar couplings is the primary object of this research. Two paramagnetic proteins, myoglobin and cytochrome b5, are chosen as targets for preliminary application. Both are well characterized structurally and should serve as suitable benchmarks for a new structural strategy. However, both have also been the subject of much debate as to motional contributions to function. Methods developed and applied to these proteins should contribute to resolution of this debate. ***