Tirion M M, ben-Avraham D, Lorenz M, Holmes K C
Department of Physics, Clarkson University, Potsdam, New York 13699-5820.
Biophys J. 1995 Jan;68(1):5-12. doi: 10.1016/S0006-3495(95)80156-6.
The slow normal modes of G-actin were used as structural parameters to refine the F-actin model against 8-A resolution x-ray fiber diffraction data. The slowest frequency normal modes of G-actin pertain to collective rearrangements of domains, motions that are characterized by correlation lengths on the order of the resolution of the fiber diffraction data. Using a small number of normal mode degrees of freedom (< or = 12) improved the fit to the data significantly. The refined model of F-actin shows that the nucleotide binding cleft has narrowed and that the DNase I binding loop has twisted to a lower radius, consistent with other refinement techniques and electron microscopy data. The methodology of a normal mode refinement is described, and the results, as applied to actin, are detailed.
G-肌动蛋白的慢正常模式被用作结构参数，以根据8埃分辨率的x射线纤维衍射数据优化F-肌动蛋白模型。G-肌动蛋白最慢频率的正常模式与结构域的集体重排有关，这些运动的特征是相关长度约为纤维衍射数据的分辨率。使用少量的正常模式自由度（≤12）显著改善了对数据的拟合。优化后的F-肌动蛋白模型表明，核苷酸结合裂隙变窄，DNase I结合环扭曲到更小的半径，这与其他优化技术和电子显微镜数据一致。本文描述了正常模式优化的方法，并详细介绍了应用于肌动蛋白的结果。
