Marassi F M, Ramamoorthy A, Opella S J
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Proc Natl Acad Sci U S A. 1997 Aug 5;94(16):8551-6. doi: 10.1073/pnas.94.16.8551.
Complete resolution of the amide resonances in a three-dimensional solid-state NMR correlation spectrum of a uniformly 15N-labeled membrane protein in oriented phospholipid bilayers is demonstrated. The three orientationally dependent frequencies, 1H chemical shift, 1H-15N dipolar coupling, and 15N chemical shift, associated with each amide resonance are responsible for resolution among resonances and provide sufficient angular restrictions for protein structure determination. Because the protein is completely immobilized by the phospholipids on the relevant NMR time scales (10 kHz), the linewidths will not degrade in the spectra of larger proteins. Therefore, these results demonstrate that solid-state NMR experiments can overcome the correlation time problem and extend the range of proteins that can have their structures determined by NMR spectroscopy to include uniformly 15N-labeled membrane proteins in phospholipid bilayers.
在取向磷脂双层中均匀 15N 标记的膜蛋白的三维固态 NMR 相关谱中，酰胺共振峰的完全分辨得以证明。与每个酰胺共振相关的三个取向依赖频率，即 1H 化学位移、1H - 15N 偶极耦合和 15N 化学位移，负责共振峰之间的分辨，并为蛋白质结构测定提供足够的角度限制。由于在相关 NMR 时间尺度（10 kHz）上蛋白质被磷脂完全固定，较大蛋白质的谱线宽度在谱图中不会变差。因此，这些结果表明固态 NMR 实验可以克服相关时间问题，并将能够通过 NMR 光谱确定其结构的蛋白质范围扩展到包括磷脂双层中均匀 15N 标记的膜蛋白。
