Department of Food Science & Technology, University of California, Davis, CA 95616, USA.
J Magn Reson. 2010 Mar;203(1):138-43. doi: 10.1016/j.jmr.2009.12.012. Epub 2009 Dec 21.
We present the development of an Overhauser dynamic nuclear polarization (DNP) instrument at 0.04 T using 1.1 GHz (L-band) electron spin resonance frequencies (ESR) and 1.7 MHz (1)H nuclear magnetic resonance frequencies. Using this home-built DNP system, the electron-nucleus coupling factor of 4-oxo-TEMPO dissolved in water was determined as 0.39+/-0.06 at 0.04 T. The higher coupling factor obtained at this field compared to higher magnetic fields, such as 0.35 T, directly translates to higher enhancement of the NMR signal and opens up a wider time scale window for observing water dynamics interacting with macromolecular systems, including proteins, polymers or lipid vesicles. The higher enhancements obtained will facilitate the observation of water dynamics at correlation times up to 10 ns, that corresponds to more than one order of magnitude slower dynamics than accessible at 0.35 T using X-band ESR frequencies.
我们展示了一种在 0.04 T 下使用 1.1 GHz（L 波段）电子自旋共振频率（ESR）和 1.7 MHz（1）H 核磁共振频率的过氧化物动态核极化（DNP）仪器的开发。使用这个自制的 DNP 系统，我们确定了溶解在水中的 4-氧-TEMPO 的电子-核耦合因子在 0.04 T 下为 0.39+/-0.06。与更高的磁场（如 0.35 T）相比，在该磁场下获得的更高的耦合因子直接转化为 NMR 信号的更高增强，并为观察与大分子系统（包括蛋白质、聚合物或脂质囊泡）相互作用的水动力学打开了更宽的时间尺度窗口。更高的增强将有助于观察相关时间长达 10 ns 的水动力学，这对应于比使用 X 波段 ESR 频率在 0.35 T 下可访问的动力学慢一个数量级以上。
