Seminar by Dr. Ana Damjanovic

Johns Hopkins University, Baltimore

Overview of constant pH simulations and recent progress in ion channel simulations

I will present an overview of constant pH simulations and discuss why these calculations are challenging.  I will also present our latest work on constant pH simulations of ion channels. The calculations suggest that at physiological pH, the channel can exist in several protonation states. Protonation of the channel results in decreased ionic population of the channel and a loss of conductance. Ions can also modulate the protonation state of the selectivity filter. We analyze the symmetry of the channel: the deprotonated state of selectivity filter is closest to C

symmetry observed in crystal structures of the open state, while the protonated states display greater levels of asymmetry and could correspond to the inactivated state which possesses a C

symmetry in the crystal structure.