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Force Spectroscopy of Single Protein Molecules Using an Atomic Force Microscope
Published on: February 28, 2019
Methods and estimations of uncertainties in single-molecule dynamic force spectroscopy
Oscar Björnham1, Staffan Schedin
1Department of Applied Physics and Electronics, Umeå University, 901 87, Umeå, Sweden.
European Biophysics Journal : EBJ
|May 23, 2009
Summary
Accurate dynamic force spectroscopy requires careful data processing. Using a Gaussian function overestimates molecular bond off-rates by over 30%, highlighting the need for better fitting methods.
Area of Science:
- Biophysics
- Materials Science
- Physical Chemistry
Background:
- Dynamic force spectroscopy (DFS) measures single molecular bond rupture forces.
- Rupture forces are variable and depend on loading rate, complicating analysis.
- Accurate parameter extraction necessitates robust measurement and data processing strategies.
Purpose of the Study:
- To analyze methods for minimizing and assessing errors in DFS.
- To evaluate the impact of different experimental and evaluation techniques.
- To identify optimal data processing strategies for accurate molecular bond parameter determination.
Main Methods:
- Numerical simulations were employed to analyze various DFS methodologies.
- Different fitting functions were tested for their accuracy in parameter extraction.
- The influence of loading rate variations and noise on precision was investigated.
Main Results:
- The choice of fitting function significantly impacts parameter accuracy; Gaussian functions introduce systematic errors.
- Using a Gaussian function overestimates the thermal off-rate by over 30%.
- Reducing the number of loading rates improved precision for bond length and thermal off-rate under unbiased noise.
Conclusions:
- Standard Gaussian fitting in DFS is inadequate and leads to significant overestimation of thermal off-rates.
- Optimized data processing, including appropriate fitting functions, is crucial for reliable DFS results.
- The minimum number of measurements for precise bond strength determination likely exceeds the commonly cited ~100.
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