Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, 590-0494, Japan.
Graduate School of Medical Life Science, Yokohama City University, Yokohama, 230-0045, Japan.
Sci Rep. 2020 Dec 10;10(1):21678. doi: 10.1038/s41598-020-78311-4.
Incoherent quasielastic neutron scattering (iQENS) is a fascinating technique for investigating the internal dynamics of protein. However, low flux of neutron beam, low signal to noise ratio of QENS spectrometers and unavailability of well-established analyzing method have been obstacles for studying internal dynamics under physiological condition (in solution). The recent progress of neutron source and spectrometer provide the fine iQENS profile with high statistics and as well the progress of computational technique enable us to quantitatively reveal the internal dynamic from the obtained iQENS profile. The internal dynamics of two proteins, globular domain protein (GDP) and intrinsically disordered protein (IDP) in solution, were measured with the state-of-the art QENS spectrometer and then revealed with the newly developed analyzing method. It was clarified that the average relaxation rate of IDP was larger than that of GDP and the fraction of mobile H atoms of IDP was also much higher than that of GDP. Combined with the structural analysis and the calculation of solvent accessible surface area of amino acid residue, it was concluded that the internal dynamics were related to the highly solvent exposed amino acid residues depending upon protein's structure.
非相干准弹性中子散射（iQENS）是一种研究蛋白质内部动力学的迷人技术。然而，低通量的中子束、低信噪比的 QENS 光谱仪以及缺乏成熟的分析方法一直是在生理条件（溶液中）下研究内部动力学的障碍。最近中子源和光谱仪的进展提供了具有高精度统计数据的精细 iQENS 谱，以及计算技术的进展使我们能够从获得的 iQENS 谱中定量揭示内部动态。使用最先进的 QENS 光谱仪测量了溶液中两个蛋白质（球状域蛋白（GDP）和固有无序蛋白（IDP））的内部动力学，然后使用新开发的分析方法进行了揭示。结果表明，IDP 的平均弛豫率大于 GDP，IDP 的可移动 H 原子分数也远高于 GDP。结合结构分析和氨基酸残基溶剂可及表面积的计算，得出结论，内部动力学与蛋白质结构取决于高度暴露于溶剂的氨基酸残基有关。
