title: Nonlinear and asymmetric open channel characteristics of an ion-selective porin in planar membranes.
abstract: The open channel characteristics of the bacterial porin Omp32 from Comamonas acidovorans were investigated by means of conductance measurements in planar lipid bilayers of the Montal-Mueller type. Particularly at low salt conditions (< or = 30 mM KCl) Omp32 exhibited some unusual asymmetric and nonlinear functional properties. Current-voltage relationship measurements showed that conductance depends on the orientation of porin molecules and is a nonlinear function of the applied membrane potential. Conductance also depends on the salt concentration in a manner not common to porins and the salt concentration modulates the nonlinearity of conductance-voltage relationships. Omp32 is strongly anion-selective. The nonlinear and asymmetric conductance of the open channel is a new observation in porins.
authors.affiliation: Max-Planck-Institut für Biochemie, Abteilung Molekulare Strukturbiologie, Martinsried, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mathes
authors.forename: H
authors.initials: H
authors.lastname: Engelhardt
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D004553:Electric Conductivity; D016946:Gram-Negative Aerobic Rods and Cocci / Q000378:metabolism; D007473:Ion Channels / Q000737:chemistry* / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry; D008564:Membrane Potentials; D009994:Osmolar Concentration; D018272:Porins / Q000737:chemistry* / Q000378:metabolism*; D011189:Potassium Chloride
chemical_list: D007473:Ion Channels; D008051:Lipid Bilayers; D018272:Porins; D011189:Potassium Chloride