Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706.
Proc Natl Acad Sci U S A. 1980 Nov;77(11):6289-92. doi: 10.1073/pnas.77.11.6289.
(25)Mg NMR spectroscopy is applied to a study of magnesium ion interactions with DNA, which is considered as a model for a linear polyelectrolyte. It is demonstrated that the magnesium ion spectrum is complicated by a non-Lorent-zian line shape and is dominated by the effects of chemical exchange with macromolecule binding sites. A distinction is made between specific-site interactions in which the magnesium ion loses a water molecule from the first coordination sphere on binding and those interactions, referred to as territorial binding, in which the ion maintains its first coordination sphere complement of solvent. The first type of site-binding interactions are shown to dominate the magnesium ion NMR spectrum, based on a consideration of the magnitudes of the observed (25)Mg relaxation rates compared with (23)Na relaxation rates, the clear contributions of chemical exchange-limited relaxation, and an ion displacement experiment employing sodium.
(25)Mg NMR 光谱学被应用于研究镁离子与 DNA 的相互作用，DNA 被认为是线性聚电解质的模型。结果表明，镁离子谱线由于非 Lorent-zian 线型而变得复杂，并受到与大分子结合位点的化学交换的影响。在结合过程中，镁离子从第一配位层失去一个水分子的特定位置相互作用与所谓的区域结合（territorial binding）被区分开来，在区域结合中，离子保持其第一配位层溶剂的完整配位。基于观察到的（25）Mg 弛豫率与（23）Na 弛豫率的大小相比、化学交换限制弛豫的明显贡献以及采用钠的离子位移实验，表明第一类位结合相互作用主导了镁离子 NMR 谱。
