Electrochemical studies of antibiotic 23187 (A23187) mediated permeability to divalent heavy-metal ions in phospholipid monolayers adsorbed on mercury electrodes

Abstract

The effect of the carboxylic ionophore, A23187, on the permeability of adsorbed phospholipid monolayers to heavy-metal ions has been investigated using cyclic voltammetry. The influence of different cationic interactions and complexing agents in solution on the ionophore transport has been studied. A23187 selectively increases the permeability of the monolayer to Cd^II and Cu^II ions. The ionophore complexes the metal ion in the monolayer. This complex induces a conformational change in the monolayer at a critical potential, releasing the metal ion for reduction at the electrode surface. The oxidation of the metal and thus its transport from the electrode to the solution is always inhibited. The rate of Cd^II transfer through the ionophore system is faster than that of Cu^II, Mg^II, La^III and protons interfere with the metal ion transport by binding active sites within the ionophore system.