Structure and Dynamics of Proteins from NMR Orientational Data

9726341 Prestegard这项工作的总体目标是探索一种关于溶液中蛋白质结构和动力学的潜在新信息源。新的信息来自于最近在具有高度各向异性磁化率的分子的核磁共振谱中看到的残余偶极耦合，当这些分子被置于非常高的磁场中时。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取向。因此，测量可以通过约束大分子远程部分的取向来提供结构信息，而这些方式是现有的基于NOE的距离约束无法获得的。联轴器也受到运动平均的影响。这一点特别重要，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，实验可能会让我们深入了解大幅度、较慢的运动，这些运动最有可能对蛋白质功能做出贡献。设计和测试剩余偶极子耦合的测量和分析方法是本研究的主要目的。两种顺磁性蛋白质，肌红蛋白和细胞色素b5被选为初步应用的靶点。两者在结构上都有很好的特点，应作为新的结构战略的适当基准。然而，关于运动对功能的贡献，两者也一直是许多争论的主题。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. ***