Liu Yun
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA.
Phys Rev E. 2017 Feb;95(2-1):020501. doi: 10.1103/PhysRevE.95.020501. Epub 2017 Feb 16.
The neutron-spin-echo method (NSE) is a powerful technique for studying internal dynamics of macromolecules in solutions because it can simultaneously probe length and time scales comparable to intramolecular density fluctuations of macromolecules. Recently, there has been increased, strong interest in studying protein internal motions using NSE. The coherent intermediate scattering function (ISF) measured by NSE depends on internal, rotational, and translational motions of macromolecules in solutions. It is thus critical, but highly nontrivial, to separate the internal motion from other motions in order to properly understand protein internal dynamics. Even though many experiments are performed at relatively high concentrations, current theories of calculating the ISF of concentrated protein solutions are either inaccurate or flawed by incorrect assumptions for realistic protein systems with anisotropic shapes. Here, a theoretical framework is developed to establish the quantitative relationship of different motions included in the ISF. This theory based on the dynamic decoupling approximation is applicable to a wide range of protein concentrations, including dilute cases. It is also, in general, useful for studying many other types of macromolecule systems studied by NSE.
中子自旋回波方法（NSE）是研究溶液中大分子内部动力学的一种强大技术，因为它可以同时探测与大分子分子内密度涨落相当的长度和时间尺度。最近，人们对使用NSE研究蛋白质内部运动的兴趣日益浓厚。通过NSE测量的相干中间散射函数（ISF）取决于溶液中大分子的内部、旋转和平移运动。因此，为了正确理解蛋白质内部动力学，将内部运动与其他运动分离至关重要，但极具挑战性。尽管许多实验是在相对较高的浓度下进行的，但目前计算浓缩蛋白质溶液ISF的理论要么不准确，要么因对具有各向异性形状的实际蛋白质系统的错误假设而存在缺陷。在此，建立了一个理论框架来确定ISF中包含的不同运动之间的定量关系。这个基于动态解耦近似的理论适用于广泛的蛋白质浓度范围，包括稀溶液情况。一般来说，它对于研究通过NSE研究的许多其他类型的大分子系统也很有用。
