ETH Zurich, Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland.
Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
J Chem Phys. 2019 Jul 21;151(3):034102. doi: 10.1063/1.5111081.
Nuclear magnetic resonance (NMR) is sensitive to dynamics on a wide range of correlation times. Recently, we have shown that analysis of relaxation rates via fitting to a correlation function with a small number of exponential terms could yield a biased characterization of molecular motion in solid-state NMR due to limited sensitivity of experimental data to certain ranges of correlation times. We introduced an alternative approach based on "detectors" in solid-state NMR, for which detector responses characterize motion for a range of correlation times and reduce potential bias resulting from the use of simple models for the motional correlation functions. Here, we show that similar bias can occur in the analysis of solution-state NMR relaxation data. We have thus adapted the detector approach to solution-state NMR, specifically separating overall tumbling motion from internal motions and accounting for contributions of chemical exchange to transverse relaxation. We demonstrate that internal protein motions can be described with detectors when the overall motion and the internal motions are statistically independent. We illustrate the detector analysis on ubiquitin with typical relaxation data sets recorded at a single high magnetic field or at multiple high magnetic fields and compare with results of model-free analysis. We also compare our methodology to LeMaster's method of dynamics analysis.
核磁共振（NMR）对广泛相关时间范围内的动力学非常敏感。最近，我们已经表明，通过拟合具有少数指数项的相关函数来分析弛豫率可能会由于实验数据对某些相关时间范围的敏感性有限，从而对固态 NMR 中的分子运动产生有偏差的描述。我们引入了一种基于固态 NMR 中的“探测器”的替代方法，其中探测器响应对于一系列相关时间的运动进行了特征化，并且减少了由于使用运动相关函数的简单模型而导致的潜在偏差。在这里，我们表明，在分析溶液状态 NMR 弛豫数据时也可能会出现类似的偏差。因此，我们已经将探测器方法适应于溶液状态 NMR，特别是将整体翻滚运动与内部运动分离，并考虑了化学交换对横向弛豫的贡献。我们证明了当整体运动和内部运动在统计上是独立的时候，可以使用探测器来描述内部蛋白质运动。我们使用在单个高磁场或多个高磁场下记录的典型弛豫数据集在泛素上演示了探测器分析，并将其与无模型分析的结果进行了比较。我们还将我们的方法与 LeMaster 的动力学分析方法进行了比较。
