Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
Curr Opin Struct Biol. 2013 Oct;23(5):734-9. doi: 10.1016/j.sbi.2013.06.016. Epub 2013 Jul 11.
NMR structural studies of large monomeric and multimeric proteins face distinct challenges. In large monomeric proteins, the common occurrence of frequency degeneracies between residues impedes unambiguous assignment of NMR signals. To overcome this barrier, nonuniform sampling (NUS) is used to measure spectra with optimal resolution within reasonable time, new correlation maps resolve previous impasses in assignment strategies, and novel selective methyl labeling schemes provide additional structural probes without cluttering NMR spectra. These advances push the limits of NMR studies of large monomeric proteins. Large multimeric and multidomain proteins are studied by NMR when individual components can also be studied by NMR and have known structures. The structural properties of large assemblies are obtained by identifying binding surfaces, by orienting domains, and employing limited distance constraints. Segmental labeling and the combination of NMR with other methods have helped popularize NMR studies of such systems.
NMR 结构研究大型单体和多聚体蛋白面临着明显的挑战。在大型单体蛋白中，残基之间的频率简并现象很常见，这阻碍了 NMR 信号的明确分配。为了克服这一障碍，非均匀采样（NUS）被用于在合理的时间内以最佳分辨率测量光谱，新的相关图谱解决了以前在分配策略方面的僵局，新颖的选择性甲基标记方案提供了额外的结构探针，而不会使 NMR 光谱混乱。这些进展推动了大型单体蛋白 NMR 研究的极限。当单个组件也可以通过 NMR 进行研究并且具有已知结构时，通过 NMR 研究大型多聚体和多结构域蛋白。通过识别结合表面、定向结构域和采用有限的距离约束来获得大型组装体的结构特性。分段标记和将 NMR 与其他方法结合使用有助于推广此类系统的 NMR 研究。
