Monitoring of the Membrane Potential in Proteoliposomes with   Incorporated Cytochrome-c Oxidase Using the Fluorescent Dye Indocyanine
  A method has been developed to monitor changes of the membrane potential across vesicle membranes in real time. Using the potential-sensitive fluorescent dye indocyanine and on the basis of water/lipid redistribution model, a calculation procedure has been introduced to estimate the membrane potential in vesicles with incorporated cytochrome-c oxidase. Physical parameters, such as vesicle size distribution and density of the lipid bilayer were estimated and used as calculation parameters. By extrapolation of transient potential change to zero time, the initial rate of the potential change (dU/dt) has been calculated. It is also shown, that the initial potential change (dU/dt) may be used to study the proton/electron stoichiometry of cytochrome-c oxidase incorporated in the vesicles. 
Yu. A. Ivashchuk-Kienbaum