  Ion channels are important proteins for physiological information transfer
and functional control. To predict the microscopic origins of their
voltage-conductance characteristics, we here applied dissipation-corrected
targeted Molecular Dynamics in combination with Langevin equation simulations
to potassium diffusion through the Gramicidin A channel as a test system.
Performing a non-equilibrium principal component analysis on backbone dihedral
angles, we find coupled protein-ion dynamics to occur during ion transfer. The
dissipation-corrected free energy profiles correspond well to predictions from
other biased simulation methods. The incorporation of an external electric
field in Langevin simulations enables the prediction of macroscopic observables
in the form of I-V characteristics.
