利用微梁表面应力研究界面吸附蛋白的构象转变（.docVIP

利用微梁表面应力研究界面吸附蛋白的构象转变( 李凯1 罗昭锋2 刘红3 张青川?1 伍小平1 1中国科学技术大学，中科院材料力学行为和设计重点实验室，合肥230027； 2中国科学技术大学生命科学学院surface stress detecting using micro-cantilever* LI Kai1, LUO Zhao-feng 2, LIU Hong?3, ZHANG Qing-chuan?1,WU Xiao-ping1 1CAS Key laboratory of mechanical behavior and design of material, University of Science and Technology of China, 2Dept. of biology, University of Science and Technology of China 3Dept. of Chemical Physics, University of Science and Technology of China, Hefei 230026 Abstract: A new method based on micro-cantilever sensors was presented and used to investigate conformational transition of interface-adsorption proteins. Trypsin molecules were grafted onto one surface of a micro-cantilever by self assemble monolayer method. Then the micro-cantilever was immersed into PBS buffer solution. The deflection of the micro-cantilever was measured using optical lever technique. The results show that the micro-cantilever deflects when PBS buffer solution was replace by guanidine hydrochloride solution．This deflection was driven by the changes of the surface stress on the micro-cantilever surface and corresponding to the process of conformation changes of the interface-adsorption trypsin molecule from a compact globule to a random coil. Subsequently, an opposite deflection occurs while using PBS buffer solution to replace guanidine hydrochloride solution. This phenomena was attributed to conformation reverting, i.e., from a random coil to a compact globule. The ability to extract the mechanical information during the conformation transition of the interface-adsorption proteins is a particular characteristic of this method, because it offers us a new viewpoint to understand the mechanism of conformation folding of interface-adsorption proteins. Key words: conformation transition； trypsin； surface stress； micro-cantilever 1.引言 随着人类基因组测序的完成，弄清作为基因表达产物的蛋白质的结构和功能[1-2]就成为当前生命科学中最为重要的问题。蛋白质由20种氨基酸以肽键连接而成，这种肽链在空间卷曲折叠成为特定的三维空间结构——即蛋白质的构象，随所处环境的不同蛋白质在空间中能表现出不同构象——即蛋白质