Translocation energy of ions in nano-channels of cell membranes
| dc.creator | Teber, Sofian | |
| dc.date | 2005-01-27 | |
| dc.date | 2005-12-07 | |
| dc.date.accessioned | 2026-07-07T06:37:29Z | |
| dc.date.available | 2026-07-07T06:37:29Z | |
| dc.description | Translocation properties of ionic channels are investigated, on the basis of classical electrostatics, with an emphasis on asymptotic formulas for the potential and field associated with a point charge in the channel. Due to image charges in the membrane, we show that ions in an infinite length channel interact via a one-dimensional (1D) Coulomb potential. The corresponding electrostatic barrier $Σ$ is characterized by a "geometric mean" screening $Σ\propto e^2 / \sqrt{ε_w ε_m}R$ ($R$ being the radius of the pore, and $ε_m \approx 2$ and $ε_w \approx 80$ the room temperature dielectric constants of membrane and water, respectively). There exists a crossover length, $x_0 \propto R \sqrt{ε_w / ε_m} \sim 6.3 R$, below which the 1D potential governs the electrostatics and beyond which the three-dimensional (3D) Coulomb potential screened by the membrane takes over. Knowledge of this length enables us to discriminate between long channels, the length $L$ of which satisfies: $L \gg 2 x_0$, and short channels for which $L \ll 2 x_0$. The latter condition is satisfied by most realistic channels ({\it e.g.}, gramicidin A where $R \approx 3 {\mathrmÅ}$, $L \approx 2.5 {\mathrm{nm}}$ and $2x_0 \approx 3.8 {\mathrm{nm}}$) whose translocation energy is therefore controlled by the part of the self-energy, $Σ$, arising from the 1D potential. On this basis, we derive an expression for $Σ$, with no fitting parameter, which applies to a generic nano-channel of length $L$ and radius $R$. | |
| dc.description | 9 revTeX4 pages (in cond-mat version), 7 figures and 2 tables. Minor modifications with respect to v1 (e.g. figures added, typos corrected). Cond-mat html abstract abridged to 24 lines | |
| dc.identifier | https://arxiv.org/abs/cond-mat/0501662 | |
| dc.identifier | http://arxiv.org/abs/cond-mat/0501662 | |
| dc.identifier | J. Stat. Mech. (2005) P07001 | |
| dc.identifier | doi:10.1088/1742-5468/2005/07/P07001 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/100406 | |
| dc.subject | Soft Condensed Matter | |
| dc.title | Translocation energy of ions in nano-channels of cell membranes | |
| dc.type | text |