Charge transfer mediated by nigericin in black lipid membranes.

Nigericin, in the concentration range (10(-6) M or higher) at which it uncouples intact mitochondria, was found to increase the conductance of black lipid membranes (BLM) by several orders of magnitude. The dependence of the membrane conductance on pH and K+ concentration suggests a mechanism for the transfer of charge mediated by this ionophore based on a mobile dimer with both nigericin molecules protonated and complexed with one K+. This charged complex accounts for the uncoupling effect observed in intact mitochondria.