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Force Curve Analysis and Worm-Like Chain Modeling
The example shows a worm-like chain model analysis from a protein pull off experiment. The protein has been attached to the AFM tip and during the pull off process more unfolding events occur. From the individual unfolding events the contour length is quantified.
Raw Force Curve
This show show the force curves appear when opening the file.
 
The noise can make it difficult to obtain robust and accurate results; therefore the first step of the data processing will be to filter out the noise.
 
Force curve showing protein unfolding events
Data Courtesy of: Dr. D. A Smith, Dr. J. Clarkson, Dr. D. Brockwell,
Prof. S E Radford, Prof. G. Beddard Prof. J. Trinick,Department of
Physics, Biochemistry and Molecular Biology, Chemistry and
Human Biology, University of Leeds, UK.
Filtered Force Curve
Here the noise has been removed by a Gaussian Filter, which is part of the Filter Module.
 
 Force curve filtered
Difference Curves
The curves show the difference between the originals and the filtered curves. It is seen that the main differences consist of random noise meaning that the force curve signal is preserved.
 Force curve filter difference
Corrected Curve
Here the curves have been base line corrected based on a 3rd order fit to the approach curve. Furthermore, the curves have been hysteresis corrected such that the approach and retraction curves are aligned.
Force curve hysteresis corrected
Force vs. Separation
The curves are transformed into Force vs. Separation.
Worm-Like Chain (WLC) models have been fitted to each unfolding event.
 
 Force curve Worm Like Chain, WLC Model fit
Contour Length vs. Index
Automatically calculated graph showing the contour length as function of unfolding event index. The slope reflects the average contour length of the protein.
 Contour length
Force Curve Dialog
The force curve analysis is controlled by the Force Curve Dialog.
 Force Curve Dialog 
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