19F solid-state NMR is an excellent approach for measuring long-range distances for structure determination and for studying molecular motion. For multi-fluorinated proteins, assignment of 19F chemical shifts has been traditionally carried out using mutagenesis. Here we show 2D 19F-13C correlation experiments that allow efficient assignment of the 19F chemical shifts. We have compared several rotational-echo double-resonance-based pulse sequences and 19F-13C cross polarization (CP) for 2D 19F-13C correlation. We found that direct transferred-echo double-resonance (TEDOR) transfer from 19F to 13C and vice versa outperforms out-and-back coherence transfer schemes. 19F detection gives twofold higher sensitivity over 13C detection for the 2D correlation experiment. At MAS frequencies of 25-35 kHz, double-quantum 19F-13C CP has higher coherence transfer efficiencies than zero-quantum CP. The most efficient TEDOR transfer experiment has higher sensitivity than the most efficient double-quantum CP experiment. We demonstrate these 2D 19F-13C correlation experiments on the model compounds t-Boc-4F-phenylalanine and GB1. Application of the 2D 19F-13C TEDOR correlation experiment to the tetrameric influenza BM2 transmembrane peptide shows intermolecular 13C-19F cross peaks that indicate that the BM2 tetramers cluster in the lipid bilayer in an antiparallel fashion. This clustering may be relevant for the virus budding function of this protein.

中文翻译：

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用于氟化蛋白质 19F 共振分配的二维 19F-13C 相关 NMR。


19F 固态 NMR 是长距离测量以进行结构测定和研究分子运动的绝佳方法。对于多氟化蛋白质，19F 化学位移的分配传统上是使用诱变进行的。在这里，我们展示了 2D 19F-13C 相关实验，可以有效分配 19F 化学位移。我们比较了几种基于旋转回波双共振的脉冲序列和 19F-13C 交叉极化（CP）以进行 2D 19F-13C 相关。我们发现从 19F 到 13C 的直接转移回波双共振 (TEDOR) 转移（反之亦然）优于前后相干转移方案。对于 2D 相关实验，19F 检测的灵敏度是 13C 检测的两倍。在 25-35 kHz 的 MAS 频率下，双量子 19F-13C CP 比零量子 CP 具有更高的相干传输效率。最高效的 TEDOR 传输实验比最高效的双量子 CP 实验具有更高的灵敏度。我们在模型化合物 t-Boc-4F-苯丙氨酸和 GB1 上演示了这些 2D 19F-13C 相关实验。将 2D 19F-13C TEDOR 相关实验应用于四聚体流感 BM2 跨膜肽，显示分子间 13C-19F 交叉峰，表明 BM2 四聚体以反平行方式聚集在脂质双层中。这种聚类可能与该蛋白质的病毒出芽功能有关。