DISTANCE DISTRIBUTIONS FROM ANALYSIS OF DQC ESR DATA USING REGULARIZATION METH

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 距离分布提供了有价值的结构信息，有助于深入了解膜蛋白和构象异质水溶性蛋白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超过两次旋转的情况。例如，在完全标记的 KcsA 通道中，有四个自旋标签，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用作附加参数，有助于以高置信度确定距离分布。然后，当只有一小部分通道处于打开状态时，这些分布可用于查找通道选通时距离的变化。 T4-溶菌酶充当了确定可用于解决从 DQC-ESR 光谱中查找分布的逆问题的方法的试验场。 使用氘代溶剂在 17GHz 下获得了 T4-L 65/135 和 61/135 突变体的高质量数据。以6秒的时间尺度记录具有良好信噪比的DQC信号，并通过Tikhonov正则化方法进行分析。这项工作中的分布形状与我们之前通过反复试验对 T4-L 进行的研究中发现的分布一致。在这项工作的理论部分，正则化方法被证明优于 SVD 方法。 通过从 L 曲线准则获得正则化参数，可以通过 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.