Brandes R, Rupprecht A, Kearns D R
Department of Chemistry, University of California, San Diego, La Jolla 92093-0342.
Biophys J. 1989 Oct;56(4):683-91. doi: 10.1016/S0006-3495(89)82715-8.
High resolution 2H nuclear magnetic resonance (NMR) was used to investigate the interaction of D2O with solid samples of uniaxially oriented Li-DNA (B-form DNA) and Na-DNA (A- and B-form DNA). At low levels of hydration, 0 approximately 4 D2O/nucleotide, the 2H spectra shows a very weak (due to short T2) broad single resonance, suggestive of unrestricted rotational diffusion of the water. At approximately 5 or more D2O/nucleotide, the Li-DNA (B-form) spectra suddenly exhibit a large doublet splitting, characteristic of partially ordered water. With increasing hydration, the general trend is a decrease of this splitting. From our analysis we show that the DNA water structure reorganizes as the DNA is progressively hydrated. The D2O interaction with Na-DNA is rather different than with Li-DNA. Below 10 D2O/nucleotide Na-DNA is normally expected to be in the A-form, and a small, or negligible splitting is observed. In the range 9-19 D2O/nucleotide, the splitting increases with increasing hydration. Above approximately 20 D2O/nucleotide Na-DNA converts entirely to the B-form and the D2O splittings are then similar to those found in Li-DNA. We show that the complex Na-DNA results obtained in the range 0-20 D2O/nucleotide are caused by a mixture of A- and B-DNA in those samples.
高分辨率2H核磁共振（NMR）被用于研究重水（D2O）与单轴取向的锂-DNA（B型DNA）和钠-DNA（A型和B型DNA）固体样品之间的相互作用。在低水合水平下，即每核苷酸约0至4个D2O时，2H谱显示出非常微弱（由于T2短）的宽单峰共振，这表明水的旋转扩散不受限制。在每核苷酸约5个或更多D2O时，锂-DNA（B型）谱突然出现一个大的双峰分裂，这是部分有序水的特征。随着水合作用的增加，这种分裂的总体趋势是减小。通过我们的分析表明，随着DNA逐渐水合，DNA的水结构会重新组织。D2O与钠-DNA的相互作用与锂-DNA相当不同。在每核苷酸10个D2O以下，钠-DNA通常预期为A型，观察到的分裂很小或可忽略不计。在9至19个D2O/核苷酸范围内，分裂随着水合作用的增加而增大。在每核苷酸约20个D2O以上，钠-DNA完全转变为B型，此时D2O的分裂与锂-DNA中的相似。我们表明，在0至20个D2O/核苷酸范围内获得的复杂钠-DNA结果是由那些样品中A型和B型DNA的混合物引起的。
