Electrochemical Elucidation of the Facilitated Ion Transport Across a Bilayer Lipid Membrane in the Presence of Neutral Carrier Compounds

Abstract

The ion transport facilitated by neutral carrier compounds (valinomycin, nonactin) has been investigated by cyclic voltammetry in the several electrolyte solutions (KF, KCl, KBr, KNO 3 , KSCN, KClO 4 ), and we demonstrated the effect of the counter anions on the facilitated transport of K þ from the viewpoint of electroneutrality. Voltammograms for the ion transport were generated at steady state and the current density between W1 and W2, j W1-W2, increased with the absolute value of the applied membrane potential, E W1-W2 . Then, the magnitude of j W1-W2 at a certain E W1-W2 increased with the hydrophobicity of the counter anion. It was proved that the logarithm of j j W1-W2 j at a certain E W1-W2 is almost proportional to the hydration energy of the counter anion. This indicates that not only K þ but also the counter anion distributes into the BLM. Therefore, the magnitude of j W1-W2 at a certain E W1-W2 increased with an increase of pH, because the hydroxide ion was served as a counter anion. Based on the variation of the zero-current potential in case of various asymmetrical ionic compositions, it is found that the amount of cation transport is much larger than that of anion transport.

Coupling of Proton Transport across Planar Lipid Bilayer and Electron Transport Catalyzed by Membrane-bound Enzyme <small>D</small>-Fructose Dehydrogenase

“…The author's group has elucidated that the properties of ionic distribution between aqueous and BLM phases are identical to those between aqueous and organic phases. 31,32 Curves 1 and 2 in Fig. 6 are the schematic voltammograms at the W1«BLM and the BLM«W2 interfaces.…”

Electrochemical Investigation on Permeability of Organic Acid Ions Through Amphotericin B Channels

“…According to Goldman's equation, we can estimate the theoretical zero-current potential, and the ion permeability through AmB channels is evaluated quantitatively. 9 The membrane potential observed experimentally (E obs ) is the sum of E W1«BLM , E M and E BLM«W2 . In this model, the sum of E W1«BLM and E BLM«W2 reaches zero because the distribution equilibrium between the aqueous and the BLM phases is established.…”

Analysis of Ion Transport through a Single Channel of Gramicidin A in Bilayer Lipid Membranes

“…[7][8][9] Since the electrochemical cell system using the BLM is convenient to structurally control the ionic composition of two aqueous phases and lipid constituents, it is easy to evaluate the permeability of all electrolyte ions and the influence of lipid components on the ion transport. 9,10 Gramicidin A (GA) isolated from Bacillus brevis is a linear pentadecapeptide, as shown in Fig. S1, and exhibits antibiotic activity.…”