The investigation of the structure and conformational dynamics of biomolecules under physiological conditions is challenging for structural biology. Although pulsed electron paramagnetic resonance (like PELDOR) techniques provide long‐range distance and orientation information with high accuracy, such studies are usually performed at cryogenic temperatures. At room temperature (RT) PELDOR studies are seemingly impossible due to short electronic relaxation times and loss of dipolar interactions through rotational averaging. We incorporated the rigid nitroxide spin label Ç into a DNA duplex and immobilized the sample on a solid support to overcome this limitation. This enabled orientation‐selective PELDOR measurements at RT. A comparison with data recorded at 50 K revealed averaging of internal dynamics, which occur on the ns time range at RT. Thus, our approach adds a new method to study structural and dynamical processes at physiological temperature in the <10 μs time range with atomistic resolution.

中文翻译：

---

脉冲EPR光谱揭示了室温下核酸的动力学

在生理条件下对生物分子的结构和构象动力学的研究对于结构生物学是具有挑战性的。尽管脉冲电子顺磁共振（如PELDOR）技术可提供高精度的远程距离和方向信息，但此类研究通常在低温下进行。室温下（RT）PELDOR研究似乎是不可能的，这是由于较短的电子弛豫时间和通过旋转平均损失的偶极相互作用所致。我们将刚性一氧化氮自旋标记Ç掺入了DNA双链体中，并将​​样品固定在固相支持物上，以克服这一限制。这将在RT上启用方向选择性PELDOR测量。与以50 K记录的数据进行的比较表明，内部动力学的平均值在RT的ns时间范围内发生。因此，