Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany.
J Am Chem Soc. 2011 Aug 31;133(34):13375-9. doi: 10.1021/ja201244u. Epub 2011 Aug 8.
Pulsed Electron-Electron Double Resonance (PELDOR) on double-stranded DNA (ds-DNA) was used to investigate the conformational flexibility of helical DNA. Stretching, twisting, and bending flexibility of ds-DNA was determined by incorporation of two rigid nitroxide spin labels into a series of 20 base pair (bp) DNA duplexes. Orientation-selective PELDOR experiments performed at both X-band (9 GHz/0.3 T) and G-band (180 GHz/6.4 T) with spin label distances in the range of 2-4 nm allowed us to differentiate between different simple models of DNA dynamics existing in the literature. All of our experimental results are in full agreement with a dynamic model for ds-DNA molecules, where stretching of the molecule leads to a slightly reduced radius of the helix induced by a cooperative twist-stretch coupling.
脉冲电子-电子双共振（PELDOR）在双链 DNA（ds-DNA）上的应用，用于研究螺旋 DNA 的构象灵活性。通过将两个刚性氮氧自由基自旋标记物掺入一系列 20 个碱基对（bp）的 DNA 双链体中，确定了 ds-DNA 的拉伸、扭曲和弯曲灵活性。在 X 波段（9 GHz/0.3 T）和 G 波段（180 GHz/6.4 T）上进行的取向选择性 PELDOR 实验，自旋标记物之间的距离在 2-4nm 范围内，使我们能够区分文献中存在的不同简单 DNA 动力学模型。我们所有的实验结果都与 ds-DNA 分子的动力学模型完全一致，在该模型中，分子的拉伸导致螺旋的半径略有减小，这是由协同扭伸耦合引起的。
