Electrochemical study on facilitated ion transport across a bilayer lipid membrane in the presence of nonactin

The facilitated ion transport from one aqueous phase (W1) to another (W2) across a bilayer lipid membrane (BLM) in the presence of nonactin (Non) as an ion carrier in a BLM was elucidated. A cation-Non complex is distributed into the BLM with an anion as a counter ion to hold the electroneutrality within the BLM phase. It was, found that the anion transferred between W1 and W2 across the BLM in the opposite direction from that of the objective cation upon applying the membrane potential. These phenomena can be interpreted based on the relation between the distribution coefficient and the hydration energy and on the dependence of the ion transport facilitated by Non through a BLM on the concentration of Non in the BLM, the stability constant of Non with cations and the hydrophobicity of both cations and anions.