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

Ion transport through a single channel of gramicidin A (GA) within the bilayer lipid membrane (BLM) between two aqueous phases (W1 and W2) has been analyzed based on the electroneutrality principle. The single-channel current increases in proportion to the magnitude of the applied membrane potential and is also dependent on the permeability coefficients of electrolyte ions (K+and Cl−). By varying the ratio of the concentration of KCl in W1 to that in W2 the ratio of the diffusion coefficient of K+in the BLM to that of Cl−in the BLM can be evaluated.