Hydrodynamic properties of DNA and DNA-lipid complex in an elongational flow field.
Hydrodynamic properties of DNA and DNA-lipid complex in an elongational flow field.
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DOI：
10.1016/j.ijbiomac.2006.08.016
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发表时间：
2007-03
影响因子：
8.2
通讯作者：
N. Sasaki;H. Ashitaka;K. Ohtomo;A. Fukui
中科院分区：
文献类型：
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作者：
N. Sasaki;H. Ashitaka;K. Ohtomo;A. Fukui
本研究的目的是确定DNA-十六烷基三甲基铵（CTA）复合物的流体力学性质之间的差异和DNA的，这可能与DNA-CTA的纤维形成能力的差异，从DNA。研究了DNA和DNA-CTA复合物对拉伸流场的响应。在这两种溶液体系中，结果表明线圈拉伸过渡。在临界应变速率下，DNA-CTA分子在乙醇-甘油溶液中的回转半径是DNA在NaCl水溶液中的回转半径的0.3-0.5倍。DNA-CTA溶液的剪切粘度远小于DNA溶液的剪切粘度，这也表明DNA-CTA在乙醇-甘油溶液中的尺寸小于DNA在NaCl水溶液中的尺寸。DNA-CTA体系的平台双折射值仅为DNA体系的1/10左右。有一种经验确定的DNA-CTA复合物的分子模型，其中DNA分子被CTA链制成的圆柱形外壳包裹。这种结构降低了DNA分子密度在一个纯拉伸流场区域，但不能解释所观察到的双折射强度的减少。与DNA相比，DNA-CTA的平台双折射值较小，这是由于DNA-CTA体系中DNA分子和CTA链的特殊构象降低了分子的极化率，如构象模型所预期的那样。
The aim of this study was to determine the difference between hydrodynamic properties of DNA–cetyltrimethylammonium (CTA) complex and those of DNA, which may be related to the difference in fibre-forming ability of DNA–CTA from that of DNA. Responses of DNA and DNA–CTA complex to an elongational flow field were investigated. In both solution systems, results suggesting a coil–stretch transition were obtained. From a critical strain rate value, the radius of gyration of DNA–CTA molecules in ethanol–glycerol solution was revealed to be 0.3–0.5 times of that of DNA in aqueous NaCl solution. Shear viscosity of DNA–CTA solution was much smaller than that of DNA solution, also suggesting a smaller size of DNA–CTA in ethanol–glycerol solution than that of DNA in aqueous NaCl solution. The plateau birefringence value of the DNA–CTA system, a parameter that indicates the local molecular conformation and the molecular arrangement, was only about 1/10 of that of the DNA system. There is an empirically determined molecular model of DNA–CTA complex in which a DNA molecule is sheathed by a cylindrical crust made of CTA chains. This structure reduces the DNA molecular density in a pure elongational flow field region but cannot explain the observed reduction of birefringence intensity. The small plateau birefringence value of DNA–CTA compared with that of DNA was attributed to the reduced molecular polarizability by the particular conformation of DNA molecules and CTA chains in the DNA–CTA system such as that expected by the conformational models.