Nonequilibrium, Single-Molecule Studies of Protein Unfolding

***准确了解蛋白质系统平衡状态之间的能量差对于理解分子过程的生物物理和生物化学非常重要。该奖项将支持一个专注于开发有效技术的项目，以在分子水平上研究这种能量差异或蛋白质稳定性。这些研究将有助于我们对蛋白质稳定性的理解，并最终帮助我们理解在生理条件下蛋白质稳定性在正常功能中的作用。原子力光谱是一种用于测量分子在拉伸或扭曲力作用下的行为的技术。将这项技术应用于人类心脏titin等重要分子，将有助于了解心脏肌肉的功能。将开设一门新的分子生物物理学课程。学生和博士后将有机会学习使用最先进的仪器进行生物物理学研究。本项目得到材料研究部和物理部的支持。***技术摘要***该个人研究者奖将支持利用原子力显微镜动态力谱技术进行蛋白质自由能景观的单分子研究。目标是从非平衡测量中获得纳米级生物分子系统的平衡信息。最先进的原子力显微镜能够在纳米尺度上操纵单个分子，并以皮牛顿精度检测力，将用于测量单个蛋白质的力延伸。最近导出的Jarzynski等式，它将非平衡功值的概率分布与平衡自由能差联系起来，将用于确定蛋白质进行机械转化时的自由能变化。titin是一种巨大的肌肉蛋白，负责心肌的被动张力，其展开的自由能曲线将利用Jarzynski方程得到。该计划的广泛影响包括开发一种新的测量和分析工具，用于解决基本的生物物理问题，以及培养纳米生物物理学方面的本科生、研究生和博士后。本项目得到材料研究部和物理部的支持。

***NON-TECHNICAL ABSTRACT***An accurate knowledge of the energy difference between equilibrium states of protein systems is important for biophysical and biochemical understanding of molecular processes. This award will support a project focused on developing effective techniques to study this energy difference, or protein stability, at the molecular level. The studies will aid our understanding of protein stability, and ultimately our understanding of the role of protein stability in proper functioning under physiological conditions. Atomic force spectroscopy is a technique used to measure the behavior of molecules under a stretching or twisting force. Application of this technique to important molecules such as human cardiac titin will lead to understanding of how the muscle functions in heart. A new course on molecular biophysics will be developed. Students and postdoctoral associates will have the opportunity to learn to use the state-of-the art instrument for biophysics research. This project receives support from the Division of Materials Research and the Physics Division.***TECHNICAL ABSTRACT***This individual investigator award will support single-molecule studies of protein free energy landscapes by dynamic force spectroscopy using atomic force microscopy. The goal is to obtain equilibrium information about nanoscale biomolecular systems from non-equilibrium measurements. State-of-the art atomic force microscopy capable of manipulating single molecules at the nanometer scale and detecting forces with pico-newton accuracy will be used to measure the force-extension of single proteins. The recently derived Jarzynski equality, which relates the probability distribution of nonequilibrium work values to the equilibrium free energy difference, will be used to determine the free energy changes as proteins undergo mechanical transformations. The unfolding free energy curves of titin, the giant muscle protein responsible for the passive tension of heart muscles, will be obtained using Jarzynski's equality. The broader impact of this program includes the development of a novel measurement and analysis tool for solving basic biophysical problems and the training of undergraduate students, graduate students, and postdoctoral associates in nanobiophysics. This project receives support from the Division of Materials Research and the Physics Division.