title: Effects of extreme pH on ionic transport through protein nanopores: the role of ion diffusion and charge exclusion.
abstract: We combine electrophysiological experiments with the structure-based Poisson-Nernst-Planck 3D calculations to investigate the transport properties of the bacterial porin OmpF under large pH gradients and particularly low salt concentrations. We show that under extreme pH conditions protons and hydroxyls contribute decisively to the overall measured current, challenging the traditional interpretation of some electrokinetic parameters such as channel selectivity and rectification properties. We analyze with unprecedented detail the two intertwined factors ruling the ionic permeation through the channel, namely the differences between cation and anion mobilities and the electrostatic exclusion due to the interaction between permeating ions and channel ionizable residues.
authors.affiliation: Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain. mqueralt@uji.es.
authors.forename: María
authors.initials: M
authors.lastname: Queralt-Martín
authors.affiliation: Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain. mqueralt@uji.es.
authors.forename: Carlos
authors.initials: C
authors.lastname: Peiró-González
authors.affiliation: Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain. mqueralt@uji.es.
authors.forename: Marcel
authors.initials: M
authors.lastname: Aguilella-Arzo
authors.affiliation: Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain. mqueralt@uji.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Alcaraz
mesh_terms: D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D058608:Nanopores; D011506:Proteins
chemical_list: D011506:Proteins