Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Bethesda, MD 20892-0520, USA.
Proc Natl Acad Sci U S A. 2010 Dec 14;107(50):21441-6. doi: 10.1073/pnas.1015661107. Epub 2010 Nov 22.
Nonequilibrium pulling experiments provide detailed information about the thermodynamic and kinetic properties of molecules. We show that unperturbed free energy profiles as a function of molecular extension can be obtained rigorously from such experiments without using work-weighted position histograms. An inverse Weierstrass transform is used to relate the system free energy obtained from the Jarzynski equality directly to the underlying molecular free energy surface. An accurate approximation for the free energy surface is obtained by using the method of steepest descent to evaluate the inverse transform. The formalism is applied to simulated data obtained from a kinetic model of RNA folding, in which the dynamics consists of jumping between linker-dominated folded and unfolded free energy surfaces.
非平衡拉伸实验为分子的热力学和动力学性质提供了详细信息。我们证明，无需使用功加权位置直方图，也可以从这些实验中严格获得作为分子延伸函数的无扰自由能分布。利用逆魏尔斯特拉斯变换，将从雅可比等式中获得的系统自由能与潜在的分子自由能表面直接联系起来。通过使用最陡下降法来评估逆变换，获得了自由能表面的精确逼近。该形式体系应用于从 RNA 折叠的动力学模型中获得的模拟数据，其中动力学由链接子主导的折叠和未折叠自由能表面之间的跳跃组成。
