Raw data to "MAS NMR experiments of corynebacterial cell walls: complementary 1H- and CPMAS CryoProbe-enhanced 13C-detected experiments"

Bacterial cell walls are gigadalton-large cross-linked polymers with a wide range of motional amplitudes, including rather rigid as well as highly flexible parts. Magic-angle spinning NMR is a powerful method to obtain atomic-level information about intact cell walls. Here we investigate sensitivity and information content of different homonuclear 13C-13C and heteronuclear H-N, H-C and N-C correlation experiments. We demonstrate that a CPMAS CryoProbe yields ca. 8-fold increased signal-to-noise over a room-temperature probe, or a ca. 3-4-fold larger per-mass sensitivity. The increased sensitivity allowed to obtain high-resolution spectra even on intact bacteria. Moreover, we compare resolution and sensitivity of 1H MAS experiments obtained at 100 kHz vs. 55 kHz. Our study provides useful hints for choosing experiments to extract atomic-level details on cell-wall samples.

细菌细胞壁是具有吉道尔顿级分子量的交联聚合物，其运动幅度分布宽泛，既包含较为刚性的结构区域，也存在高度柔性的部分。魔角旋转核磁共振（Magic-angle spinning NMR）是获取完整细菌细胞壁原子级信息的有力手段。本研究针对多种同核13C-13C及异核H-N、H-C、N-C相关实验的灵敏度与信息承载量展开探究。研究证实，交叉极化魔角旋转低温探头（CPMAS CryoProbe）相较于室温探头，可使信噪比提升约8倍，或使单位质量灵敏度提升3至4倍。灵敏度的提升使得即便针对完整细菌样本，也能够获取高分辨率核磁共振谱图。此外，本研究对比了100 kHz与55 kHz转速下开展的1H魔角旋转实验的分辨率与灵敏度。本研究为选取适用于细胞壁样本原子级细节提取的实验方案提供了具有参考价值的指引。