CHEMICAL EXCHANGE BETWEEN CONFORMERS

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。 动态交换被引入到缓慢松弛局部结构(SRLS)模型的软件中。这种新的动态过程允许氮氧化物自旋标签在两个或更多个位置之间交换位置，在这些位置上，自旋标签经历不同的旋转速度和顺序。这个项目的动机是我们最近对T4溶菌酶动力学的多频率研究，其中我们清楚地区分了氮氧化物系链的两个不同的构象。然而，我们之前仅限于认为交易所在ESR时间尺度上是静态的。在这一假设下，发现必须采用不同的总体来在不同的频率上实现可接受的频谱拟合。我们认为，这是由于ESR在不同频率下的有效时间尺度不同所致。我们的新软件将使我们能够澄清这些问题，并获得构象交换率。

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. Dynamic exchange is being incorporated into the software for the Slowly Relaxing Local Structure (SRLS) model. This new dynamic process allows the nitroxide spin label to exchange positions between two or more sites where the spin label experiences different rotational rates and orderings. This project is motivated by our recent multifrequency study of T4 lysozyme dynamics where we have clearly differentiated two distinct conformers of the nitroxide tether. However, we previously were limited to considering the exchange to be static on the ESR time scale. Under this assumption it was found that different populations have to be employed to achieve acceptable spectral fits at different frequencies. We believe that this is a result of the different effective timescales of ESR at the different frequencies. Our new software will enable us to clarify these matters, and to obtain rates of conformational exchange.