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Transition paths in single-molecule force spectroscopy
Pilar Cossio1, Gerhard Hummer2, Attila Szabo3
1Biophysics of Tropical Diseases Max Planck Tandem Group, University of Antioquia, Medellín, Colombia.
The Journal of Chemical Physics
|April 2, 2018
Summary
Accurate single-molecule force spectroscopy requires faster apparatus response. Faster bead fluctuations are crucial for resolving molecular transition path times, not just folding rates.
Area of Science:
- Biophysics
- Chemical Physics
- Materials Science
Background:
- Single-molecule force spectroscopy uses laser-trapped beads and polymer linkers to probe molecular dynamics.
- Molecular (un)folding rates can be extracted from extension-time trajectories under specific conditions.
Purpose of the Study:
- To investigate the requirements for accurate measurement of molecular transition path times.
- To determine the influence of apparatus response time on the resolution of molecular unfolding events.
Main Methods:
- Analysis of single-molecule force spectroscopy data, focusing on the relationship between bead fluctuation time and molecular transition dynamics.
- Development of analytic expressions for transition path times on anisotropic 2D free energy surfaces.
Main Results:
- Accurate measurement of molecular transition path times necessitates faster apparatus response than previously thought.
- Bead fluctuations must occur more rapidly than the molecule's end-to-end distance changes for proper resolution of transition paths.
- Measured folding/unfolding rates may be valid even when transition path times are not accurately resolved.
Conclusions:
- The speed of the experimental apparatus is a critical factor in resolving molecular transition path times in force spectroscopy.
- Transition path times are sensitive to both molecular properties and the characteristics of the pulling device.
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