ALKALI CATION-TRANSPORT THROUGH LIPOSOMES BY THE ANTIMICROBIAL FUSAFUNGINE AND ITS CONSTITUTIVE ENNIATINS

Fusafungine is a peptide antibiotic mixture composed of several enniat ins and active against Gram-positive bacteria. Ionophoric properties o f fusafungine have been studied in liposomes by measuring proton-catio n exchange by both fluorescence and P-31-nuclear magnetic resonance (N MR) and have been compared to those of its constituent enniatin peptid es. Fusafungine, as well as enniatins, transport cations through a mob ile carrier mechanism selective for K+ vs. Na+ and involving two antib iotic molecules. The transport efficiencies of the various enniatins a ppear to be related to their hydrophobicity, in agreement with a previ ously proposed ''sandwich'' transport model. The ionophoric properties of crude fusafungine may be involved in its antibiotic action and its local therapeutic properties.