Effect of ionic strength on membrane potential generation in reconstituted cytochrome c oxidase.

In this study we applied the potential-sensitive fluorescent dye indocyanine to measure the initial rate of membrane potential development in liposomes containing reconstituted cytochrome c oxidase from bovine heart. A linear relationship was found between the initial rate of membrane potential development, related to the H+/e(-)-stoichiometry, and the rate of electron flow at various substrate concentrations. By increasing the salt concentration a decrease of the initial rate of membrane potential development was found.

Separation and characterization of Na+,K(+)-ATPase containing vesicles.

Na+,K(+)-ATPase was reconstituted in vesicles prepared by a dialysis method. Ion-exchange chromatography was used to obtain well characterized fractions from the inhomogeneous vesicle preparation. Lipid and protein content was determined by optical methods during the elution process.

Investigation of reconstitution of the Na, K-ATPase in lipid vesicles.

Vesicles containing Na,K-ATPase were prepared by a dialysis method in buffers with various concentrations of K+ and Na+ ions. Ion-exchange chromatography has been used to separate proteoliposomes into protein-depleted and protein-rich fractions. The pumping activity of reconstituted ion pumps has been determined in the different fractions of the vesicle preparation using voltage-dependent fluorescence dyes.