### [Special day and location] Electrostatic effects on DNA dynamics in fluid by the generalized immersed boundary method

- Series
- Applied and Computational Mathematics Seminar
- Time
- Friday, April 2, 2010 - 13:00 for 1 hour (actually 50 minutes)
- Location
- Skiles 269
- Speaker
- Sookkyung Lim – Department of Mathematical Sciences, University of Cincinnati

We investigate the effects of electrostatic and steric repulsion on thedynamics of pre-twisted charged elastic rod, representing a DNA molecule,immersed in a viscous incompressible fluid. Equations of motion of the rod, whichinclude the fluid-structure interaction, rod elasticity, and electrostatic interaction, are solved by the generalized immersed boundary method. Electrostatic interaction is treated using a modified Debye-Huckel repulsive force in which the electrostatic force depends on the salt concentration and the distance between base pairs, and a close range steric repulsion force to prevent self-penetration. After perturbation a pretwisted DNA circle collapses into a compact supercoiled configuration. The collapse proceeds along a complex trajectory that may pass near several equilibrium configurations of saddle type, before it settles in a locally stable equilibrium. We find that both the final configuration and the transition path are sensitive to the initial excess link, ionic stregth of the solvent, and the initial perturbation.