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Becucci L, Moncelli MR, Naumann R, Guidelli R.
Potassium ion transport by valinomycin across a Hg-supported
lipid bilayer.
J Am Chem Soc. 2005 Sep 28;127(38):13316-23
Department of Chemistry, Florence University, 50019 Sesto
Fiorentino, Florence, Italy.
A biomimetic membrane consisting of a lipid bilayer tethered to
a mercury electrode via a hydrophilic spacer was investigated in
aqueous KCl by potential-step chronocoulometry and
electrochemical impedance spectroscopy, both in the absence and
in the presence of the ionophore valinomycin. Impedance spectra,
recorded from 1 x 10(-2) to 1 x 10(5) Hz over a potential range
of 0.8 V, are satisfactorily fitted to a series of four RC
meshes, which are straightforwardly related to the different
substructural elements of the biomimetic membrane. The
frequency-independent resistances and conductances of both the
lipid bilayer and the hydrophilic spacer show a maximum when
plotted against the applied potential. This behavior is
interpreted on the basis of a general approximate approach that
applies the concepts of impedance spectroscopy to a model of the
electrified interphase and to the kinetics of potassium ion
transport assisted by valinomycin across the lipid bilayer.
PMID: 16173764
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