INFLUENCE OF RAPID INTRAMOLECULAR MOTION ON NMR CROSS-RELAXATION RATES - A MOLECULAR-DYNAMICS STUDY OF ANTAMANIDE IN SOLUTION
INFLUENCE OF RAPID INTRAMOLECULAR MOTION ON NMR CROSS-RELAXATION RATES - A MOLECULAR-DYNAMICS STUDY OF ANTAMANIDE IN SOLUTION
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DOI：
10.1021/ja00033a002
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发表时间：
1992-03-25
影响因子：
15
通讯作者：
ERNST, RR
中科院分区：
文献类型：
--
作者：
BRUSCHWEILER, R;ROUX, B;ERNST, RR
一个800 ps的分子动力学模拟antamanide在氯仿中已被用来研究快速的角度和径向的分子内动力学的影响，实验上可访问home-NMR交叉弛豫速率。分子内运动的相关函数，需要计算的交叉弛豫速率常数，来自分子动力学模拟。交叉弛豫中两个原子核相对运动的空间限制在分子固定坐标系中用角序参量和径向序参量来描述。据发现，一般相反的影响角和径向运动的交叉弛豫率是分离到一个很好的近似。分离的适用性进行了讨论的一些分析运动模型。当内部运动过程和整体旋转翻滚发生在一个类似的时间尺度上的逆拉莫尔频率，NOESY和ROESY交叉弛豫速率之间的系统差异预测从分子动力学模拟和解释的顺序参数和内部相关时间。讨论了结合实验NOE和ROE交叉弛豫数据提取内部运动信息的可能性。
An 800 ps molecular dynamics simulation of antamanide in chloroform has been used to study the influence of fast angular and radial intramolecular dynamics on experimentally accessible homonuclear NMR cross-relaxation rates. Correlation functions of the intramolecular motions, needed to compute the cross-relaxation rate constants, are derived from the molecular dynamics simulation. The spatial restriction of the relative motion of two nuclei involved in the cross relaxation is described by an angular and a radial order parameter in a molecule-fixed reference frame. It is found that the generally opposite effects of angular and radial motion on cross-relaxation rates are separable to a good approximation. The applicability of the separation is discussed for some analytical motional models. When internal motional processes and the overall rotational tumbling are taking place on a similar time scale as the inverse Larmor frequency, systematic differences between NOESY and ROESY cross-relaxation rates are predicted from the molecular dynamics simulation and interpreted in terms of order parameters and internal correlation times. Possibilities for extracting information on internal motion by combining experimental NOE and ROE cross-relaxation data are discussed.