Dr. François Dehez
Equipe de dynamique des assemblages membranaires, Unité mixte de recherché
Nancy Université
Cedex, France

Friday, December 14, 2007
2:00 pm (CT)
4269 Beckman Institute

Abstract

Ion channels constitute an important family of integral membrane proteins responsible for the regulation of ion transport across the cell membrane. Yet, the underlying energetics of the permeation events and how the latter are modulated by the environment, specifically near the mouth of the pore, remain only partially characterized. Here, I present recent results obtained for a synthetic membrane channel formed by cyclic peptides of alternated D- and L-hydrophobic α-amino acids. The free energy delineating the translocation of a sodium ion is measured along the conduction pathway by means of molecular dynamics simulations and is shown to strongly depend on the location of the mouth of the synthetic channel with respect to the membrane surface. We have further modeled the transport of ions trough this nanopore under the influence of a transmembrane (TM) potential gradient. Here the voltage gradient is promoted by imposing a net charge imbalance between two electrolytes separated by the phospholipid bilayer. The approach allowing generation of such TM potentials will be briefly presented.