Rybenkov V V, Vologodskiĭ A V
Mol Biol (Mosk). 1992 Nov-Dec;26(6):1433-9.
Different methods of determination of effective diameter of DNA double helix under different ionic conditions in solution are reviewed. This value is a characteristic of excluded volume effects in DNA and allows for electrostatic repulsion between segments of the molecule. The values of the effective diameter found by completely different methods are in excellent agreement. This allows to conclude that in wide range of ionic and DNA concentrations a model of unpermeable cylinders provides adequate description of DNA conformational properties. The effective double helix diameter grows rapidly with decreasing salt concentration and can be several times higher than the geometric one. Even in solutions of physiological ionic strength corresponding to 200 mM NaCl the value of the effective diameter is 5 nm. Such a sharp dependence of DNA effective diameter on salt concentration should be taken into account when analyzing conformational properties of superhelical DNA.
本文综述了在不同离子条件下溶液中DNA双螺旋有效直径的不同测定方法。该值是DNA中排除体积效应的一个特征，并且考虑了分子片段之间的静电排斥。通过完全不同的方法得到的有效直径值非常吻合。这使得我们可以得出结论，在广泛的离子浓度和DNA浓度范围内，不可渗透圆柱体模型能够充分描述DNA的构象性质。有效双螺旋直径随着盐浓度的降低而迅速增大，可能比几何直径大几倍。即使在相当于200 mM NaCl的生理离子强度溶液中，有效直径的值也是5纳米。在分析超螺旋DNA的构象性质时，应考虑DNA有效直径对盐浓度的这种强烈依赖性。
