Ion-Selective Properties Of Some Lipoid Systems And Their Relation To Biological Membranes

Bi-ionic potentials and single ionic potentials have been determined across membranes containing mixtures of sodium and potassium stearate interposed between aqueous NaCl/KCl solutions. Ionic transport numbers evaluated from these data compare well with values obtained by a direct current method. The results indicate ion-exchange properties and preferential sorption of KCl by the membrane. The discrimination of the lipoids toward Na+ and K+ is found to be caused by the hydrophobic part of the stearate aggregates. Some biological implications related to lipoprotein structures are briefly discussed.