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Abstract: CaV channels are transmembrane proteins that mediate and regulate ion fluxes across cell membranes, and they are activated in response to action potentials to allow Ca2+ influx. Since ion channels are composed of charge or polar groups, an external alternating electric field may affect the ion‐selective membrane transport and the performance of the channel. In this article, we have investigated the effect of an external GHz electric field on the dynamics of calcium ions in the selectivity filter of the CaVAb channel. Molecular dynamics (MD) simulations and the potential of mean force (PMF) calculations were carried out, via the umbrella sampling method, to determine the free energy profile of Ca2+ ions in the CaVAb channels in presence and absence of an external field. Exposing CaVAb channel to 1, 2, 3, 4, and 5 GHz electric fields increases the depth of the potential energy well and this may result in an increase in the affinity and strength of Ca2+ ions to binding sites in the selectivity filter the channel. This increase of strength of Ca2+ ions binding in the selectivity filter may interrupt the mechanism of Ca2+ ion conduction, and leads to a reduction of Ca2+ ion permeation through the CaVAb channel. [ABSTRACT FROM AUTHOR]

Ca V channels are transmembrane proteins that mediate and regulate ion fluxes across cell membranes, and they are activated in response to action potentials to allow Ca 2+ influx. Since ion channels are composed of charge or polar groups, an external alternating electric field may affect the ion-selective membrane transport and the performance of the channel. In this article, we have investigated the effect of an external GHz electric field on the dynamics of calcium ions in the selectivity filter of the Ca V Ab channel. Molecular dynamics (MD) simulations and the potential of mean force (PMF) calculations were carried out, via the umbrella sampling method, to determine the free energy profile of Ca 2+ ions in the Ca V Ab channels in presence and absence of an external field. Exposing Ca V Ab channel to 1, 2, 3, 4, and 5 GHz electric fields increases the depth of the potential energy well and this may result in an increase in the affinity and strength of Ca 2+ ions to binding sites in the selectivity filter the channel. This increase of strength of Ca 2+ ions binding in the selectivity filter may interrupt the mechanism of Ca 2+ ion conduction, and leads to a reduction of Ca 2+ ion permeation through the Ca V Ab channel., (© 2018 Wiley Periodicals, Inc.)

Activation of voltage-gated calcium channels by action potentials leads to the influx of Ca 2+ ions. In this study, the ion permeation characteristics in bacterial voltage-gated calcium (Ca V Ab) channels were investigated using molecular dynamics simulations. Furthermore, the potential of mean force (PMF) calculations was evaluated to determine the free energy profile for the permeation of cations (Ca 2+ and Na + ) and anions (Cl - ) in the Ca V Ab channel. The results showed that both Ca 2+ and Na + cations experienced a deep energy well, while the Cl - anion experienced a relatively high energy barrier at the center of the selectivity filter (site 2). Consistent with the experimental data, the results obtained from this study demonstrate that sites 2 and 3 displayed the highest and lowest affinities to Ca 2+ , respectively. These findings also indicate that Na + can easily and quickly pass through the Ca V Ab channel in the absence of Ca 2+ , while Cl - ions lack this ability.