Poisson-Nernst-Planck-Fermi theory for modeling biological ion channels

摘要: A Poisson-Nernst-Planck-Fermi (PNPF) theory is developed for studying ionic transport through biological ion channels. Our goal to deal with the finite size of particle using a Fermi like distribution without calculating forces between particles, because they are both expensive and tricky compute. We include steric effect ions water molecules nonuniform sizes interstitial voids, correlation crowded different valences, screening in an inhomogeneous aqueous electrolyte. Including volume voids particles important new part presented here. distributions all species derived from exclusion classical particles. Volume resulting saturation phenomena especially describe binding permeation mechanisms narrow channel pore. The Gibbs free energy reduces that Boltzmann when these effects not considered. entropy extended form — called Gibbs-Fermi describes mixing configurations thermodynamic system where microstates do have equal probabilities. PNPF model dynamic flow ions, molecules, as well electric fields protein charges. also provides quantitative mean-field description charge/space competition mechanism within highly charged results good accord experimental currents recorded 108-fold range Ca2+ concentrations. illustrate anomalous mole fraction effect, signature L-type calcium Moreover, numerical concerning density, dielectric permittivity, void volume, provide useful details study variety physical ranging binding, permeation, blocking, flexibility, channel.