Nanometre distance measurements with EPR using different spin probes.

脉冲电子顺磁共振（EPR）谱是一种新兴的远距离测量技术。稀疏的长程距离对于理解复杂纳米结构的结构和柔性是非常有价值的。具体而言，使用称为PELDOR（脉冲电子-电子双共振）或DEER（双电子-电子共振）的EPR方法，可以可靠地测量所研究系统中两个顺磁中心之间的距离，最大可达10 nm。这些顺磁性中心可以是天然金属离子或自由基辅因子，但最常见的是，它们是通过一种称为定点自旋的技术故意引入的，该项目的目的是探索不同类型的顺磁中心被采用自旋标签，并牢固地建立最佳做法的选择标签，特别是关于的信息量，可以从样品中提取标记有几个光谱不同的探针（正交标记）。为此，将采用带有顺磁性金属中心和有机基团的化学模型，使用基于两个频率激发（PELDOR）或基于弛豫的方法（RIDME）的不同方法对金属氮氧化物距离测量进行基准测试。在第二步中，将仔细检查具有多个自旋中心的系统。这对于多聚体系统中的应用将是极其有价值的，其中几个自旋标记的单体组装到功能单元。特别是，在复杂结构内解决特定距离将是一个巨大的信息增益。这些模型研究将通过数值模拟来支持，并且设想将结果转移到模型蛋白质多聚体。这种方法将添加到军械库的结构EPR技术的长期目标是确定系统中的结构变化，目前的方法无法访问。

Pulse electron paramagnetic resonance (EPR) spectroscopy is an emerging technique for long range distance determination. Sparse long-range distances are very valuable for understanding structure and flexibility of complex nanostructures. Specifically, using an EPR method called PELDOR (pulsed electron-electron double resonance) or DEER (double electron-electron resonance), it is possible to reliably measure distances of up to 10 nm and beyond between two paramagnetic centres in the system studied. These paramagnetic centres can be native metal ions or radical cofactors, but most commonly they are deliberately introduced by a technique called site-directed spin-labelling.This project aims to explore different types of paramagnetic centres to be employed a spin labels and to firmly establish best practices for the choice of labels especially with respect to the amount of information that can be extracted from samples labelled with several spectroscopically distinct probes (orthogonal labelling). To this end chemical models bearing paramagnetic metal centres and organic radicals will be employed to benchmark the metal nitroxide distance measurements using different methods based on excitation with two frequencies (PELDOR) or relaxation based methods (RIDME). In a second step systems bearing multiple spin centres will be scrutinised. This will be extremely valuable for applications in multimeric systems in which several spin-labelled monomers assemble to the functional unit. In particular addressing specific distances within the complex structure will be a huge gain in information. These model studies will be backed up by numeric simulations and the outcome is envisioned to be transferred to a model protein multimer. This approach will add to the armoury of structural EPR techniques with the long term aim of identifying structural changes in systems not accessible with current methods.