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Kinetics of interior loop formation in semiflexible chains
Changbong Hyeon1, D Thirumalai
1Biophysics Physics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA.
The Journal of Chemical Physics
|March 18, 2006
Summary
Interior loop formation in semiflexible chains is crucial for biomolecular folding. Chain stiffness and ionic strength significantly impact loop formation kinetics, as validated by Brownian dynamics simulations.
Area of Science:
- Biophysics
- Polymer Physics
Background:
- Loop formation is fundamental to biomolecular folding and DNA bending.
- Semiflexible chains exhibit complex interior looping dynamics.
Purpose of the Study:
- To analytically calculate the interior distance distribution function for semiflexible chains.
- To develop a kinetic model for interior looping using Kramers theory.
- To investigate the influence of chain stiffness and ionic strength on loop formation.
Main Methods:
- Analytical calculation using a mean-field approach.
- Derivation of the potential of mean force.
- Application of Kramers theory for kinetic analysis.
- Comparison with Brownian dynamics simulations of the wormlike chain (WLC) model.
Main Results:
- Theoretical predictions show excellent agreement with simulations for DNA-like parameters.
- Interior looping times (tauIC) are sensitive to the relative stiffness of the loop and dangling ends.
- Flexible dangling ends enhance interior loop formation rates.
- Charged monomers and low ionic strength significantly increase cyclization (tauc) and interior looping (tauIC) times.
Conclusions:
- The effective persistence length governs both cyclization and interior looping times.
- The WLC model with an effective persistence length can effectively describe experimental observations in biomolecules.
- Understanding interior looping kinetics is vital for biomolecular folding and DNA mechanics.