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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Dielectric behavior of DNA in water-organic co-solvent mixtures
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Dielectric behavior of DNA in water-organic co-solvent mixtures

机译：DNA在水-有机助溶剂混合物中的介电行为

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The radiowave dielectric dispersions of DNA in different water-organic co-solvent mixtures have been measured in the frequency range from 100 kHz to 100 MHz, where the polarization mechanism is generally attributed to the confinement of counterions within some specific lengths, either along tangential or perpendicular to the polyion chain. The dielectric dispersions have been analyzed on the basis of two partially different dielectric models, a continuum counterion fluctuation model proposed by Mandel and a discrete charged site model, proposed by Minakata. The influence of the quality of the solvent on the dielectric parameters has been investigated in water-methanol and water-glycerol mixtures at different composition, by varying the permittivity epsilon(m) and the viscosity eta of the solvent phase. The analysis of the dielectric spectra in solvents where electrostatic and hydrodynamic interactions vary with the solvent composition suggests that both the two models are able, in principle, to account for the observed high-frequency dielectric behavior. However, while some certain assumptions are necessary about the polyion structure within the Mandel model, no structural prerequisite is needed within the Minakata model, where the polarization mechanism invoked considers a radial counterion exchange with the outer medium, which is largely independent of the local polyion conformation. (c) 2005 Elsevier B.V. All rights reserved.
机译：已在100 kHz至100 MHz的频率范围内测量了DNA在不同水-有机共溶剂混合物中的无线电波电介质分散体，其中极化机制通常归因于抗衡离子限制在某些特定长度内（沿切线方向或沿切线方向）垂直于聚离子链。在两个部分不同的介电模型的基础上分析了介电弥散，这两个模型分别是Mandel提出的连续抗衡离子涨落模型和Minakata提出的离散带电位点模型。通过改变介电常数ε和溶剂相的粘度η，在不同组成的水-甲醇和水-甘油混合物中，研究了溶剂质量对介电参数的影响。在静电和流体动力相互作用随溶剂组成变化的溶剂中的介电谱分析表明，两个模型原则上都能够解释观察到的高频介电行为。然而，尽管在Mandel模型中对聚离子结构有一些特定的假设是必要的，但在Minakata模型中并不需要任何结构前提，在该模型中，所调用的极化机制考虑了与外部介质的径向抗衡离子交换，这在很大程度上与局部聚离子无关构象。 （c）2005 Elsevier B.V.保留所有权利。

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