Electrostatics in biomolecular systems

Benoit Roux

Electrostatic interactions manifest themselves under a wide range of situations in biomolecular systems. While certainly approximate, simple models based on macroscopic continuum dielectric media can be extremely useful to capture the dominant physical effects associated with electrostatics. A classic approach to treat the solvent as a continuum relies on the finite-difference Poisson-Boltzmann (PB) equation. In particular, numerical solution to the PB equation can be used to calculate the solvation free energy of a biomolecule. In this presentation, I will discuss the sensitive physical aspects of the finite-difference PB equation from a perspective anchored in statistical mechanics. I will also show how PB theory can be extended to account for the effect of membrane voltage on embedded proteins, and to calculate the so-called gating charge of voltage-activated ion channels. Finally, applications to various biophysical systems will be described.