Influence of Ca2+ and Temperature on the Interaction of Gangliosides with Valinomycin in Mixed Monolayers at the Air/Water Interface1

Abstract
The effects of Ca2+ and temperature on mixed ganglioside-valinomycin-monolayers at the air/water interface were studied. Surface pressure-area isotherms of the pure gangliosides (GM1, GDla) exhibited the typical monolayer characteristics. Pressure-area isotherms of the cyclodepsipeptide, valinomycin, were determined. In mixed monolayers, positive and negative deviation from the mean molecular area indicated the two components were miscible. Especially in GDla mixtures, the addition of 0.01 mM calcium exhibited, with low molar fractions of valinomycin, a demixing effect in the direction of the phase separation of the components.