A pH-tunable nanofluidic diode: electrochemical rectification in a reconstituted single ion channel |
| |
Authors: | Alcaraz Antonio Ramírez Patricio García-Giménez Elena López M Lidón Andrio Andreu Aguilella Vicente M |
| |
Institution: | Department of Experimental Sciences, Biophysics Unit, University Jaume I, P.O. Box 8029, E-12080 Castellón, Spain. |
| |
Abstract: | We report pH-dependent electrochemical rectification in a protein ion channel (the bacterial porin OmpF) reconstituted on a planar phospholipid membrane. The measurements performed at single-channel level show that the electric current is controlled by the protein fixed charge and it can be tuned by adjusting the local pH. Under highly asymmetric pH conditions, the channel behaves like a liquid diode. Unlike other nanofluidic devices that display also asymmetric conductance, here the microscopic charge distribution of the system can be explored by using the available high-resolution (2.4 A) channel crystallographic structure. Continuum electrostatics calculations confirm the hypothesized bipolar structure of the system. The selective titration of the channel residues is identified as the underlying physicochemical mechanism responsible for current rectification. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|