ELECTRIC BIREFRINGENCE OF DNA RESTRICTION FRAGMENTS

DNA限制性片段与强电场的相互作用 将使用瞬变电学技术进行研究 双折射。反转野外实验将证明 DNA分子在构象上经历了一个渐进的变化 场强。克尔常数随反离子变化的研究 集中度和类型将对曼宁的理论进行测试 反离子凝聚，以及Mandel和O‘Konski理论 电极化率。关于很小的克尔常数的研究 片段将显示最近观察到的L2依赖关系 长度上的电极化率(因此感生偶极子)扩展到 小于100个碱基对的片段。双折射饱和曲线 将作为反离子浓度和类型的函数来测量。这个 结果将与双折射衰减曲线相关联，以便 解释双折射与电的表观线性关系 中等场强区域的场强。嵌入层 进入DNA螺旋的染料分子将用单分散研究 片段，以显示DNA螺旋是否真的是 通过插层拉长的。最后，电场对电磁场的影响。 将研究DNA的热变性。所有这一切的结果 实验将阐明DNA分子在强电中的行为 场，从而可以识别作用在DNA上的电动力 细胞中的分子；典型细胞的电势 薄膜与电磁场具有相同的数量级 双折射实验。这项研究的长期目标是 了解DNA的物理性质并确定其电学性质 作用在聚电解质上的力。

The interaction of DNA restriction fragments with strong electric fields will be investigated using the technique of transient electric birefringence. Reversing field experiments will demonstrate whether the DNA molecules undergo a progressive change in conformation with increasing field strength. Studies of the Kerr constant as a function of counterion concentration and type will provide a test of the Manning theory of counterion condensation, as well as the Mandel and O'Konski theories of electric polarizability. Studies of the Kerr constant of very small fragments will show whether the recently observed L2 dependence of the electric polarizability (and hence the induced dipole) on length extends to fragments smaller than 100 base pairs. Birefringence saturation curves will be measured as a function of counterion concentration and type. The results will be correlated with the birefringence decay curves in order to interpret the apparent linear dependence of the birefringence on electric field strength in intermediate field strength regions. Intercalation of dye molecules into the DNA helix will be investigated with monodisperse fragments, in order to show whether or not the DNA helix is actually elongated by intercalation. Finally, the effect of electric fields on the thermal denaturation of DNA will be studied. The results of all these experiments will clarify the behavior of DNA molecules in strong electric fields, and thus can identify the electrical forces acting on the DNA molecule in the cell; the electrical potential across a typical cell membrane is of the same order of magnitude as the fields used in electric birefringence experiments. The long range goals of this research are to understand the physical properties of DNA and to determine the electrical forces acting on polyelectrolytes.