Interaction of lucensomycin with membranes: the role of non-steroidal components.

The binding of lucensomycin to unilamellar phospholipid/cholesterol vesicles and to colloidal emulsions of cholesterol in aqueous solutions was studied by monitoring the changes in the electronic absorption spectra of the polyene antibiotic. The total extent of the absorption variations was a direct function of cholesterol concentration and quite independent of the nature of the emulsion. The rate of binding, relatively slow in the colloidal systems, was greatly enhanced when cholesterol was included in phospholipid-containing membranes. The rate of lucensomycin binding to colloidal cholesterol increased with increasing cholesterol concentrations and/or stirring the heterogeneous suspension. The time course of lucensomycin binding to vesicles appeared to be independent of the concentrations of phospholipids and cholesterol.