Levy R M, Sheridan R P
Biophys J. 1983 Feb;41(2):217-21. doi: 10.1016/S0006-3495(83)84422-1.
A simple model is presented for the motion of phenylalanine and tyrosine rings in proteins. The model consists of restricted rotational diffusion of the rings about the side chain C alpha--C beta (chi 1) and C beta--C gamma (chi 2) axes combined with 180 degree ring flips. The model is used to evaluate order parameters for nuclear magnetic resonance relaxation and fluorescence depolarization probes of aromatic ring motions in proteins. The dependence of the order parameters on orientation in the ring plane is examined and it is demonstrated that in the presence of ring flips, additional ring librations can have a large effect on the probe order parameters.
本文提出了一个关于蛋白质中苯丙氨酸和酪氨酸环运动的简单模型。该模型由环围绕侧链Cα-Cβ（χ1）和Cβ-Cγ（χ2）轴的受限旋转扩散与180度的环翻转组合而成。该模型用于评估蛋白质中芳香环运动的核磁共振弛豫和荧光去极化探针的序参量。研究了序参量对环平面中取向的依赖性，并证明在存在环翻转的情况下，额外的环摆动会对探针序参量产生很大影响。
