Stoichiometry of hemolysis by the polyene antibiotic lucensomycin.

The stoichiometry of hemolysis by the polyene antibiotic lucensomycin was investigated. It appears that hemolysis occurs only when a relatively high fraction (probably between 15 and 40%) of the cholesterol sites in the erythrocyte membrane have combined with the polyene. Also in phospholipid-cholesterol vesicles the increase of permeability requires occupancy of 40-50% of the existing cholesterol sites. As for the possible cooperative effect in the hemolytic process, it is probable that several (at least 9-10) lucensomycin-cholesterol adducts must interact on each side of the membrane to form an aqueous channel; the distribution of these adducts in the erythrocyte membrane occurs, however, apparently at random.