title: Ionophore properties of cationomycin in large unilamellar vesicles studied by 23Na- and 39K-NMR.
abstract: Cationomycin, isolated from Actinomadura azurea belongs to a large family of carboxylic polyether antibiotics, transporting monovalent cations through membranes by a mobile carrier mechanism, leading globally to an H+, M+ exchange. In this report the cation transporting properties of cationomycin were characterized in large unilamellar vesicles (LUVs) by 23Na- and 39K-NMR. Kinetic studies showed that cationomycin transported potassium more rapidly than sodium, and the more stable complex was formed with potassium at the water/membrane interface. The transport rate constants measured for cationomycin were compared with those obtained for monensin. Cationomycin transports Na+ more slowly than monensin and has a lower stability complex with Na+ because of the lower formation rate for the complex on the membrane surface. Our results show that transport selectivity of cationomycin is in favour of K+ versus Na+ while the reverse situation is observed for monensin. The relationships between the ionophore properties of cationomycin and monensin with their biological activities are discussed.
authors.affiliation: Laboratoire de Synthèse, Université Blaise Pascal-CNRS, Aubiere, France.
authors.forename: A M
authors.initials: AM
authors.lastname: Delort
authors.forename: G
authors.initials: G
authors.lastname: Jeminet
authors.forename: S
authors.initials: S
authors.lastname: Sareth
authors.forename: F G
authors.initials: FG
authors.lastname: Riddle
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D005663:Furans / Q000008:administration & dosage / Q000494:pharmacology*; D007476:Ionophores / Q000008:administration & dosage / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D011197:Potassium Radioisotopes; D012979:Sodium Radioisotopes; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D005663:Furans; D007476:Ionophores; D008567:Membranes, Artificial; D011197:Potassium Radioisotopes; D012979:Sodium Radioisotopes; C022174:cationomycin