DISTANCE DISTRIBUTIONS FROM ANALYSIS OF DQC ESR DATA USING REGULARIZATION METH

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。距离分布提供了有价值的结构信息，可以帮助提供洞察膜蛋白和构象异质性水溶性蛋白质的静态结构以及这些结构的波动。确定距离分布的另一个重要方面是两个以上自旋的情况。例如，在完全标记的KcsA通道中，有四个自旋标记，由于对称性考虑，有两个可能的距离。这两个距离和化学计量可以用作附加参数，其可以帮助以高置信度确定距离分布。然后，这些分布可以用于在只有一部分通道处于打开状态时找到通道门控时的距离变化。T4-溶菌酶作为试验场，用于确定可用于解决从DQC-ESR谱中找到分布的逆问题的方法。使用氘代溶剂在17 GHz下获得了T4-L 65/135和61/135突变体的高质量数据。在6s的时间尺度上记录了具有良好信噪比的DQC信号，并用Tikhonov正则化方法进行了分析。在这项工作中的分布的形状是一致的分布在我们以前的研究中发现的T4-L的试错。在这项工作的理论部分，正则化方法被证明优于SVD方法。从L曲线准则中得到正则化参数，便于用Tikhonov正则化方法将DQC-ESR信号直接转换为距离分布。

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. Distance distributions provide valuable structural information that could help to provide insight into the static structure of membrane proteins and conformationally heterogeneous water soluble proteins as well as fluctuations in these structures. Another important aspect of determining distance distributions is the case of more than two spins. For example, in fully-labeled KcsA channels there are four spin-labels, with two possible distances due to symmetry considerations. The two distances and the stoichiometry could be used as additional parameters that could help to determine distance distributions with a high degree of confidence. These distributions could then be used to find the change in distances upon channel gating when only a fraction of the channels is in the open state. T4-Lysozyme served as testing ground for determining methods useful for solving the inverse problem of finding the distributions from the DQC-ESR spectra. High-quality data were obtained on T4-L 65/135 and 61/135 mutants at 17GHz with use of deuterated solvents. The DQC signals with excellent SNR were recorded on a time-scale of 6s and analyzed by the Tikhonov regularization method. The shapes of the distributions in this work are consistent with the distributions found in our previous study of T4-L by trial and error. In the theoretical part of this work, regularization methods were shown to outperform SVD methods. A direct conversion of DQC-ESR signals into distance distributions by the Tikhonov regularization method was facilitated by obtaining the regularization parameter from the L-curve criterion.