Veselkov A N, Moroshkin V A, Poliakova I D, Shpungin I L, Frisman Z V
Mol Biol (Mosk). 1976 Sep-Oct;10(5):1050-60.
The conformation of the denatured DNA molecule of different molecular weights in the solutions of various ionic composition was studied by the methods of viscometry, light scattering and flow birefringence. Formaldehyde purified from metallic ions with the help of ionites was used for fixation of the denatured state of the DNA molecule. It has been shown that theories developed for flexible macromolecules are in a sufficient accordance with hydrodynamical and optical data. The unperturbed dimensions, equilibrium rigidity of the macromolecule in solutions of different ionic strengths, mu, were determined. In the range of mu greater than or equal to 0.005 the length of Kuhn's segment (A) is equal to approximately 40 A and its value increases with an increase of mu. At mu 0.001 A approximately 60 A and mu 0.0005 A approximately 85 divided by 100 A. A relation between intrinsic viscosity and molecular weight of the denatured DNA molecule was established. Data on the flow birefringence in the solutions of the denatured DNA have shown that the sigh of optical anisotrophy of the macromolecule depends on the ionic strength. The observed dependency may be explained only by assuming that ionic strength influences the equilibrium orientation of nitrogen base planes with respect to the main chain of the macromolecule.
通过粘度测定法、光散射法和流动双折射法研究了不同分子量的变性DNA分子在各种离子组成溶液中的构象。借助离子交换剂从金属离子中纯化得到的甲醛用于固定DNA分子的变性状态。结果表明，为柔性大分子发展的理论与流体动力学和光学数据充分相符。测定了不同离子强度（μ）溶液中大分子的无扰尺寸、平衡刚性。在μ大于或等于0.005的范围内，库恩链段长度（A）约为40 Å，其值随μ的增加而增大。在μ为0.001时，A约为60 Å，在μ为0.0005时，A约为85至100 Å。建立了变性DNA分子特性粘度与分子量之间的关系。变性DNA溶液中流动双折射的数据表明，大分子光学各向异性的符号取决于离子强度。观察到的这种依赖性只能通过假设离子强度影响氮碱基平面相对于大分子主链的平衡取向来解释。
