Rectification properties and pH-dependent selectivity of meningococcal class 1 porin
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Otros documentos de la autoría: Cervera, Javier; Komarov, Alexander G.; Aguilella, Vicente
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Mostrar el registro completo del ítemcomunitat-uji-handle:10234/9
comunitat-uji-handle2:10234/2507
comunitat-uji-handle3:10234/6973
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http://dx.doi.org/10.1529/biophysj.107.116186 |
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Título
Rectification properties and pH-dependent selectivity of meningococcal class 1 porinFecha de publicación
2008ISSN
63495Cita bibliográfica
Biophysical Journal, 94, 4, p. 1194-1202Tipo de documento
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info:eu-repo/semantics/publishedVersionResumen
We studied the current rectification properties and selectivity of class 1 porin (PorA) from Neisseria meningitidis (strain H44/76 A3A4) reconstituted in planar lipid membranes varying salt concentrations and pH. PorA ... [+]
We studied the current rectification properties and selectivity of class 1 porin (PorA) from Neisseria meningitidis (strain H44/76 A3A4) reconstituted in planar lipid membranes varying salt concentrations and pH. PorA channel shows voltage gating with a characteristic time remarkably longer than other porins. Its current-voltage asymmetry, evaluated as the current rectification ratio, changes nonmonotonically with salt concentration. Interestingly, it reaches its maximum value at physiological concentration. Porin selectivity, quantified by reversal potential measurements, is also significantly asymmetric. Depending on the direction of the salt gradient, the channel becomes more or less selective (10:1 vs. 5:1 Na<sup>+</sup>/C<sup>-</sup>) Besides, the reversal potential measurements suggest that porin inserts directionally following the concentration gradient. Measurements over a wide range of pH show that although PorA is strongly cation selective at pH >6, its selectivity gradually changes to anionic in an acidic medium (pH < 4). We show that a continuum electrodiffusion model quantitatively accounts for conductance and reversal potential measurements at positive and negative applied voltages. © 2008 by the Biophysical Society. [-]
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