Subpiconewton Dynamic Force Spectroscopy Using Magnetic Tweezers

We introduce a simple method for dynamic force spectroscopy with magnetic tweezers. This method allows application of subpiconewton force and twist control by calibration of the applied force from the height of the magnets. Initial dynamic force spectroscopy experiments on DNA molecules revealed a l...

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Bibliographic Details
Published in:Biophysical journal 2008-03, Vol.94 (6), p.2343-2348
Main Authors: Kruithof, M., Chien, F., de Jager, M., van Noort, J.
Format: Article
Language:English
Subjects:
Beads
Biophysics - instrumentation
Biophysics - methods
Calibration
Chromatin
Chromatin - chemistry
Deoxyribonucleic acid
DNA - chemistry
Dynamics
Hysteresis
Magnetics
Magnetism
Microscopy, Atomic Force
Microspheres
Models, Statistical
Models, Theoretical
Molecules
Nucleosomes - chemistry
Optical Tweezers
Real time
Spectroscopy
Spectroscopy, Imaging, Other Techniques
Spectrum analysis
Spectrum Analysis - methods
Time Factors
Viscous drag
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Summary:We introduce a simple method for dynamic force spectroscopy with magnetic tweezers. This method allows application of subpiconewton force and twist control by calibration of the applied force from the height of the magnets. Initial dynamic force spectroscopy experiments on DNA molecules revealed a large hysteresis that is caused by viscous drag on the magnetic bead and will conceal weak interactions. When smaller beads are used, this hysteresis is sufficiently reduced to reveal intramolecular interactions at subpiconewton forces. Compared with typical quasistatic force spectroscopy, a significant reduction of measurement time is achieved, allowing the real-time study of transient structures and reaction intermediates. As a proof of principle, nucleosome-nucleosome interactions on a subsaturated chromatin fiber were analyzed.
ISSN:0006-3495
1542-0086
DOI:10.1529/biophysj.107.121673