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Channel Activity of OmpF Monitored in Nano-BLMs

Eva K. Schmitt ^*, Maarten Vrouenraets  and Claudia Steinem ^*

^* Institut für Analytische Chemie, Chemo- und Biosensorik, Universität Regensburg, 93040 Regensburg, Germany; and Biomade Technology Foundation, 9747 AG Groningen, The Netherlands

Correspondence: Address reprint requests to Claudia Steinem, Institut für Analytische Chemie, Chemo- und Biosensorik, Universität Regensburg, 93040 Regensburg, Germany. Tel.: 49-941-943-4548; Fax: 49-941-943-4491; E-mail: claudia.steinem{at}chemie.uni-regensburg.de.

Free-standing lipid bilayer membranes can be formed on small apertures (60 nm diameter) on highly ordered porous alumina substrates. The formation process of the membranes on a 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol submonolayer was followed by impedance spectroscopy. After lipid bilayers had thinned, the reconstitution and ionic conducting properties of the outer membrane protein OmpF of E. coli were monitored using single-channel recordings. The characteristic conductance states of the three monomers, fast kinetics, and subconductance states were observed. Blockade of the ion flow as a result of interaction of the antibiotic ampicillin with the protein was verified, indicating the full functionality of the protein channel in nanometer-scale bilayer membranes.