The interaction of the polyene antibiotic lucensomycin with cholesterol in erythrocyte membranes and in model systems. I. A fluorometric and spectrophotometric study.

The increase of fluorescence emission of lucensomycin occurring upon interaction with cholesterol, either as colloidal suspension or included in phospholipid micelles or in erythrocyte membranes, was described. Colloidal cholesterol differed from that contained in membranes by the kinetic behavior of its interaction with lucensomycin, the reaction being very slow in the former case, very fast in the latter one. Variations of optical density also occurred, though neither the kinetics nor the titration curves were superimposable on those obtained fluorometrically. The stoichiometry was, however, the same.