The Membrane Potential and its Representation by a Constant Electric Field in Computer Simulations.

@article{citeulike:3033328, abstract = {A theoretical framework is elaborated to account for the effect of a transmembrane potential in computer dynamics simulations. It is shown that a simulation with a constant external electric field applied in the direction normal to the membrane is equivalent to the influence of surrounding infinite baths maintained to voltage difference via ion-exchanging electrodes connected to an electromotive force (EMF). It is also shown that the linearly-weighted displacement charge within the simulation system tracks the net flow of charge through the external circuit comprising the EMF and the electrodes. Using a statistical mechanical reduction of the degrees of freedom of the external system, three distinct theoretical routes are formulated and examined for the purpose of characterizing the free energy of a protein embedded in a membrane that is submitted to a voltage difference. The W-route is constructed from the variations in the voltage-dependent potential of mean force (PMF) along a reaction path connecting two conformations of the protein. The Q-route is based on the average displacement charge as a function of the conformation of the protein. Finally, the G-route considers the relative charging free energy of specific residues, with and without applied membrane potentials. The theoretical formulation is illustrated with a simple model of an ion crossing a vacuum slab surrounding by two aqueous bulk phases and with a fragment of the voltage-sensor of the KvAP potassium channel.}, address = {University of Chicago.}, author = {Roux, Benoit }, citeulike-article-id = {3033328}, doi = {http://dx.doi.org/10.1529/biophysj.108.136499}, issn = {1542-0086}, journal = {Biophysical journal}, keywords = {emf, implicit, membrane, potential}, month = {July}, posted-at = {2008-07-22 18:57:28}, priority = {2}, title = {The Membrane Potential and its Representation by a Constant Electric Field in Computer Simulations.}, url = {http://dx.doi.org/10.1529/biophysj.108.136499}, year = {2008} }

TY - JOUR ID - citeulike:3033328 L3 - citeulike-article-id:3033328 TI - The Membrane Potential and its Representation by a Constant Electric Field in Computer Simulations. JF - Biophysical journal AD - University of Chicago. SN - 1542-0086 N2 - A theoretical framework is elaborated to account for the effect of a transmembrane potential in computer dynamics simulations. It is shown that a simulation with a constant external electric field applied in the direction normal to the membrane is equivalent to the influence of surrounding infinite baths maintained to voltage difference via ion-exchanging electrodes connected to an electromotive force (EMF). It is also shown that the linearly-weighted displacement charge within the simulation system tracks the net flow of charge through the external circuit comprising the EMF and the electrodes. Using a statistical mechanical reduction of the degrees of freedom of the external system, three distinct theoretical routes are formulated and examined for the purpose of characterizing the free energy of a protein embedded in a membrane that is submitted to a voltage difference. The W-route is constructed from the variations in the voltage-dependent potential of mean force (PMF) along a reaction path connecting two conformations of the protein. The Q-route is based on the average displacement charge as a function of the conformation of the protein. Finally, the G-route considers the relative charging free energy of specific residues, with and without applied membrane potentials. The theoretical formulation is illustrated with a simple model of an ion crossing a vacuum slab surrounding by two aqueous bulk phases and with a fragment of the voltage-sensor of the KvAP potassium channel. KW - emf KW - implicit KW - membrane KW - potential AU - Roux, Benoit PY - 2008/07/18/ UR - http://dx.doi.org/10.1529/biophysj.108.136499 ER -