Mechanismus und Selektivität des Alkali-Ionentransportes in Modell-Membranen in Gegenwart des Antibioticums Valinomycin

Selective transport of potassium ions through synthetic membranes impregnated with valinomycin in octane-2-ol in the presence of equal amounts of K⁺ and Na⁺ or Li⁺ ions is induced on application of a potential difference across these membranes. By using ¹⁴C-labelled valinomycin it is shown that transport of potassium ions is accompanied by an equivalent transport of valinomycin within the membrane, consistent with the formation of a 1 : 1 complex of K⁺ with valinomycin. The exchange of ligands is shown to occur during the transport process so that a carrier-relay mechanism, as proposed earlier for macrotetrolide-mediated potassium transport, accounts for all experimental results on the bulk membranes studied.