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Unzipping dynamics of long DNAs
Simona Cocco1, Rémi Monasson, John F Marko
1Laboratoire de Dynamique des Fluides Complexes, 3 rue de l'Université, 67000 Strasbourg, France.
Summary
DNA double helix strands can be unzipped with 15 pN force. At high speeds, viscous drag alters unzipping force, deviating from equilibrium predictions.
Area of Science:
- Biophysics
- Molecular Biology
- Physical Chemistry
Background:
- The DNA double helix is a stable structure requiring force to separate its strands.
- Understanding DNA unzipping dynamics is crucial for molecular manipulation and biological processes.
Purpose of the Study:
- To analyze the dynamics of DNA double helix unzipping and rezipping at constant velocities.
- To investigate the influence of high unzipping speeds and rotational viscous drag on DNA unzipping forces.
Main Methods:
- Theoretical analysis of DNA unzipping and rezipping dynamics.
- Modeling the effects of constant velocity separation and reapproach of DNA molecule ends.
- Incorporating rotational viscous drag and elastic torque into force calculations.
Main Results:
- Equilibrium-based theory accurately describes unzipping below 1000 bases/second for 50-kilobase DNAs.
- At higher velocities, rotational viscous drag causes elastic torque, leading to forces deviating significantly from equilibrium values during unzipping and rezipping.
- Analysis includes sequence-dependent effects and transient force buildup delays.
Conclusions:
- High-speed DNA unzipping deviates from equilibrium predictions due to viscous drag effects.
- The study explains recent experimental observations of altered unzipping forces at high velocities.
- Understanding these dynamics is vital for precise control of DNA manipulation.