Schiemann Olav, Prisner Thomas F
Institute of Physical and Theoretical Chemistry, Center for Biomolecular Magnetic Resonance, J. W. Goethe-University Frankfurt, 60438 Frankfurt am Main, Germany.
Q Rev Biophys. 2007 Feb;40(1):1-53. doi: 10.1017/S003358350700460X. Epub 2007 Jun 13.
Electron paramagnetic resonance (EPR) spectroscopy provides a variety of tools to study structures and structural changes of large biomolecules or complexes thereof. In order to unravel secondary structure elements, domain arrangements or complex formation, continuous wave and pulsed EPR methods capable of measuring the magnetic dipole coupling between two unpaired electrons can be used to obtain long-range distance constraints on the nanometer scale. Such methods yield reliably and precisely distances of up to 80 A, can be applied to biomolecules in aqueous buffer solutions or membranes, and are not size limited. They can be applied either at cryogenic or physiological temperatures and down to amounts of a few nanomoles. Spin centers may be metal ions, metal clusters, cofactor radicals, amino acid radicals, or spin labels. In this review, we discuss the advantages and limitations of the different EPR spectroscopic methods, briefly describe their theoretical background, and summarize important biological applications. The main focus of this article will be on pulsed EPR methods like pulsed electron-electron double resonance (PELDOR) and their applications to spin-labeled biosystems.
电子顺磁共振（EPR）光谱学提供了多种工具来研究大型生物分子或其复合物的结构及结构变化。为了解析二级结构元件、结构域排列或复合物形成情况，能够测量两个未成对电子之间磁偶极耦合的连续波和脉冲EPR方法可用于在纳米尺度上获得长程距离限制。此类方法能够可靠且精确地测量高达80埃的距离，可应用于水性缓冲溶液或膜中的生物分子，且不受尺寸限制。它们可在低温或生理温度下应用，样品量低至几纳摩尔。自旋中心可以是金属离子、金属簇、辅因子自由基、氨基酸自由基或自旋标记物。在本综述中，我们讨论了不同EPR光谱方法的优缺点，简要描述了其理论背景，并总结了重要的生物学应用。本文的主要重点将是脉冲EPR方法，如脉冲电子 - 电子双共振（PELDOR）及其在自旋标记生物系统中的应用。
