DNA & PROTEIN DNA COMPLEXES

马丁·古特霍尔德于1997年12月1日加入该项目，与 外部生物学家在他们的研究中使用纳米操纵器。 他还将继续他的DNA调查。我们有 启动了DNA和蛋白质-DNA复合体的研究 纳米操纵器和补充生化研究。 空气中DNA的高分辨率图像现在可以常规获得。 在空气中吸附在云母上的DNA的初始推动实验中，我们被 能够在受控物质中破解DNA。经过适当的校准后 对于悬臂的侧向力常数，我们将确定 DNA的断裂力。确定摩擦力的实验， 摩擦系数和DNA在分子上运动的活化能 目前正在追捕的是海面上的人。我们已经测定了结合能 将25bP DNA片段吸附到云母上，用于一组 条件。该碎片的吸附自由能为 测得约为4.2kT，计算了能量损失 约为1kT，因此结合热约为 3.2KT。将针对不同的缓冲区进行绑定实验 底物条件和不同长度的DNA片段。我们 正在开发一种理论框架来描述 将DNA转移到底物。使用一个简单的模型，我们推导出了公式 对于自由能、自由能和自由能的长度依赖关系 吸附。包括上述参数的完整模型 加上摩擦参数和运动的活化能 表面是未来的发展方向。

Martin Guthold joined the project December 1, 1997 to work with external biologists using the nanoManipulator in their investigations. He will also be continuing his investigations of DNA. We have initiated an investigation of DNA and protein-DNA complexes using the nanoManipulator and complementary biochemical studies. High-resolution images of DNA in air can now be obtained routinely. In initial pushing experiments of DNA adsorbed on mica in air, we were able to rupture DNA in a controlled matter. After proper calibration of the lateral force constant of the cantilever we will determine the rupture force of DNA. Experiments to determine the frictional force, the friction coefficient and the activation energy to move DNA on the surface are currently pursued. We have determined the binding energy of a 25 bp DNA fragment for adsorption onto mica for one set of conditions. The free energy of adsorption for this fragment was determined to be about 4.2 kT, the entropic energy loss was calculated to be about 1 kT, and the enthalpy of binding was, therefore, about 3.2 kT. Binding experiments will be done for different buffer and substrate conditions and for DNA fragments of different length. We are developing a theoretical framework to describe the adsorption of DNA to a substrate. Using a simple model, we have derived formulas for the length dependence of the free energy, enthalpy and entropy of adsorption. A complete model including the aforementioned parameters plus frictional parameters and the activation energy for motion on the surface will be developed in the future.