COMPUTATIONAL METHODS FOR STUDYING PROTEIN AND DNA DYNAMICS BY ESR & NMR

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 中心，不一定是研究者的机构。 我们开发了新的模型和软件，用于分析蛋白质和DNA系统等大分子的ESR和NMR数据。在ESR背景下，新软件允许在不同频率下同时拟合ESR光谱，以提高对各种拟合参数的光谱分辨率。它还允许构象异构体之间的动态交换。当与缓慢松弛局部结构（SRLS）模型耦合时，多频率拟合输出将自旋标签连接到大分子的系链的局部动力学和有序性以及整个大分子复合物的整体翻滚速率。 这种方法已被应用到T4溶菌酶自旋标记在几个突变位点的动力学性质的研究。目前，我们正在进行更全面的研究T4溶菌酶动力学在更多的突变位点和更多的频率在不同的溶剂。我们正在为我们的试衣程序添加新功能。这些特征包括（1）自旋标记内部运动的非对称扩散张量和（2）具有所有三个欧拉角的内部扩散倾斜。在这个子计划的第二部分，我们在NMR弛豫理论的背景下，制定了SRLS模型来分析大分子动力学。 在蛋白质核磁共振研究中广泛使用的无模型理论的一个重要假设是两种运动模式之间的解耦。 整体蛋白质翻滚和局部运动的动力学耦合是我们理解蛋白质动力学的重要一步。该方法已成功地应用于一些蛋白质系统的动力学分析，并将用于马里兰州大学的大卫福什曼博士的NMR研究，以分析双结构域（二泛素）系统中的整体和结构域间的运动。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have developed new models and software for analyzing the ESR and NMR data from macromolecules such as protein and DNA systems. In the ESR context, the new software allows a simultaneous fit of ESR spectra at different frequencies to enhance the spectral resolution to the various fitting parameters. It also allows for dynamic exchanges between conformers. When coupled with the slowly relaxing local structure (SRLS) model, the multi frequency fit outputs the local dynamics and ordering of the tether connecting the spin label to the macromolecule as well as the overall tumbling rate of the whole macromolecule complex. This approach has been applied to the study of the dynamic properties of T4 lysozyme spin labeled at several mutant sites. Currently we are conducting a more comprehensive study of T4 lysozyme dynamics at more mutant sites and more frequencies in different solvents. We are adding new features to our fitting programs. These features include (1) an asymmetric diffusion tensor for the internal motion of the spin label and (2) an internal diffusion tilt with all three Euler angles. In the second part of this subproject, we have formulated the SRLS model within the context of NMR relaxation theory to analyze macromolecule dynamics. An important assumption of the widely used model free (MF) theory in the protein NMR community is the decoupling between the two modes of motions. The dynamical coupling of the overall protein tumbling and the local motion is an important step forward towards our understanding of the protein dynamics. This approach has been successfully applied to the dynamics analyses of a few protein systems, and will be used in a NMR study by Dr David Fushman, University of Maryland, to analyze the overall and inter-domain motions in dual-domain (di-ubiquitin) system.