Polyene antibiotic-sterol interactions in membranes of Acholeplasma laidlawii cells and lecithin liposomes. I. Specificity of the membrane permeability changes induced by the polyene antibiotics

Abstract

1. 1. The effect of filipin, amphotericin B, nsystatin, etruscomycin and pimaricin upon the permeability properties of Acholeplasma laidlawii cells and egg lecithin liposomes was investigated. When cholesterol was present in the membrane the different polyene antibiotics produced permeability changes which were different for the various antibiotics. 2. 2. Filipin disrupted the membrane structure, after the interaction with cholesterol, so that both small ions such as K + and large protein molecules like glucose-6-phosphate dehydrogenase are released. 3. 3. Amphotericin B, nystatin and etruscomycin produced specific permeability changes which indicate that these antibiotics create aqueous pores of specific size (about 8 Å in diameter) in the membrane after the interaction with cholesterol. 4. 4. Pimaricin was not able to produce permeability changes in A. laidlawii cells and egg lecithin liposomes. 5. 5. Various sterols were incorporated in A. laidlawii and liposomal membranes after which the interaction of filipin and amphotericin B with these membranes was investigated by ultraviolet spectroscopy and K + permeability. Only those sterols which had 3β-OH group, a planar molecule and hydrophobic side chain at C 17 were able to interact with these polyene antibiotics and thereby enhance the membrane permeability.