Single-Molecule Dynamics of Mechanical Coiled-Coil Unzipping
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- 作者：Thomas Bornschlö ; gl ; Matthias Rief
- 刊名：Langmuir
- 出版年：2008
- 出版时间：February 19, 2008
- 年：2008
- 卷：24
- 期：4
- 页码：1338 - 1342
- 全文大小：298K
- 年卷期：v.24,no.4(February 19, 2008)
- ISSN：1520-5827
文摘
We use atomic force microscopy (AFM) to mechanically unzip and rezip a double-stranded coiled-coil structureat varying pulling velocities. We find that force-extension traces exhibit hysteresis that grows with increasing pullingvelocity. This shows that coiled-coil unzipping and rezipping do not occur in thermal equilibrium on our experimentaltime scale. We present a nonequilibrium simulation that fully reproduces the hysteresis effects, giving detailed insightinto dynamics of coiled-coil folding. Using this model, we find that seed formation is responsible for the hysteresis.The seed consists of four 
-helical turns on both strands of the coiled coil. To obtain equilibrium information fromour nonequilibrium experiments, we used the Crooks fluctuation theorem (CFT) to calculate the equilibrium freeenergy of folding for all of the different pulling velocities. The paper presented here lays the groundwork for the studyof self-assembly properties of many physiologically relevant coiled-coil structures at the single-molecule level.
-helical turns on both strands of the coiled coil. To obtain equilibrium information fromour nonequilibrium experiments, we used the Crooks fluctuation theorem (CFT) to calculate the equilibrium freeenergy of folding for all of the different pulling velocities. The paper presented here lays the groundwork for the studyof self-assembly properties of many physiologically relevant coiled-coil structures at the single-molecule level.