University of Tennessee/Oak Ridge National Laboratory Center for Molecular Biophysics , P.O. Box 2008, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
J Phys Chem B. 2012 Apr 26;116(16):5028-36. doi: 10.1021/jp2102868. Epub 2012 Apr 13.
The derivation of mean-square displacements from elastic incoherent neutron scattering (EINS) of proteins is examined, with the aid of experiments on camphor-bound cytochrome P450cam and complementary molecular dynamics simulations. It is shown that a q(4) correction to the elastic incoherent structure factor (where q is the scattering vector) can be simply used to reliably estimate from the experiment both the average mean-square atomic displacement, <Δr(2)> of the nonexchanged hydrogen atoms in the protein and its variance, σ(2). The molecular dynamics simulation results are in broad agreement with the experimentally derived <Δr(2)> and σ(2) derived from EINS on instruments at two different energy resolutions, corresponding to dynamics on the ∼100 ps and ∼1 ns time scales. Significant dynamical heterogeneity is found to arise from methyl-group rotations. The easy-to-apply q(4) correction extends the information extracted from elastic incoherent neutron scattering experiments and should be of wide applicability.
借助樟脑结合细胞色素 P450cam 的实验和互补的分子动力学模拟，研究了从弹性非相干中子散射（EINS）中推导出蛋白质的均方位移。结果表明，可以简单地使用弹性非相干结构因子的 q(4)修正项（其中 q 是散射矢量），从实验中可靠地估计蛋白质中未交换氢原子的平均均方原子位移 <Δr(2)>及其方差 σ(2)。分子动力学模拟结果与在两种不同能量分辨率的仪器上从 EINS 得出的 <Δr(2)>和 σ(2)基本一致，对应于在 ∼100 ps 和 ∼1 ns 时间尺度上的动力学。发现由甲基旋转引起的显著动力学异质性。易于应用的 q(4)修正项扩展了从弹性非相干中子散射实验中提取的信息，应该具有广泛的适用性。
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