Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules
Practical aspects of 1H transverse paramagnetic relaxation enhancement measurements on macromolecules
复制标题
DOI：
10.1016/j.jmr.2006.10.003
复制
发表时间：
2007-02-01
影响因子：
2.2
通讯作者：
Clore, G. Marius
中科院分区：
文献类型：
--
作者：
Iwahara, Junji;Tang, Chun;Clore, G. Marius
近年来，H-1横向顺磁弛豫增强（PRE）作为一种为结构研究提供长距离信息的方法，以及作为大分子缔合中大幅度运动和低密度瞬态中间体的探针，又有了新的发展。在本文中，我们将讨论有关PRE 1H横向弛豫率（γ（2））的准确测量的各个实际方面。我们首先表明，准确的伽玛（2）率可以从两个时间点的测量，而不需要任何拟合程序或复杂的误差估计，并没有额外的精度是从多个时间点的测量记录在同一实验时间。还讨论了最小化实验误差的两个时间点的最佳设置。接下来，我们证明了文献中常用的简单的单个时间点测量，可以大大低估Gamma（2）的真实值，除非采用相对较长的重复延迟。然后，我们研究了伽玛（2）的场依赖性，并表明伽玛（2）在高磁场下只表现出非常弱的场依赖性，通常用于大分子研究。这种观察的理论基础进行了讨论。最后，我们研究了痕量顺磁性样品污染的影响（
The use of H-1 transverse paramagnetic relaxation enhancement (PRE) has seen a resurgence in recent years as method for providing long-range distance information for structural studies and as a probe of large amplitude motions and lowly populated transient intermediates in macromolecular association. In this paper we discuss various practical aspects pertaining to accurate measurement of PRE 1H transverse relaxation rates (Gamma(2)). We first show that accurate Gamma(2) rates can be obtained from a two time-point measurement without requiring any fitting procedures or complicated error estimations, and no additional accuracy is achieved from multiple time-point measurements recorded in the same experiment time. Optimal setting of the two time-points that minimize experimental errors is also discussed. Next we show that the simplistic single time-point measurement that has been commonly used in the literature, can substantially underestimate the true value of Gamma(2), unless a relatively long repetition delay is employed. We then examine the field dependence of Gamma(2), and show that Gamma(2) exhibits only a very weak field dependence at high magnetic fields typically employed in macromolecular studies. The theoretical basis for this observation is discussed. Finally, we investigate the impact of contamination of the paramagnetic sample by trace amounts (