DISTANCE DISTRIBUTIONS FROM ANALYSIS OF DQC ESR DATA USING REGULARIZATION METH

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 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不均一的水溶性蛋白的静态结构以及这些结构中的波动。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，在全标记的KCSA通道中，有四个自旋标记，由于对称性的考虑，有两个可能的距离。这两个距离和化学计量学可以作为附加参数，帮助确定高度可信的距离分布。然后，当只有一小部分通道处于打开状态时，这些分布可以用于在通道选通时发现距离的变化。T4-溶菌酶作为确定方法的试验场，用于解决从DQC-ESR谱中寻找分布的反问题。对T4-L 65/135和61/135突变体，在17 GHz频率下，用氚溶剂获得了高质量的数据。对信噪比良好的DQC信号在6s的时间尺度上进行记录，并用Tikhonov正则化方法进行分析。这些分布的形状与我们以前用试错法研究T4-L时发现的分布是一致的。在这项工作的理论部分，正则化方法被证明优于奇异值分解方法。通过从L曲线准则获得正则化参数，实现了利用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.