N-acyl Chain in Ceramide and Sphingomyelin Determines Their Mixing Behavior, Phase State and Surface Topography in Langmuir Films

DUPUY, FERNANDO GABRIEL; MAGGIO, BRUNO

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Lugar: Washington; Año: 2014 vol. 118 p. 7475 - 7487

1520-6106

Sphingolipids are membrane lipids composed by a long chain aminediol base, usually sphingosine, with a N-linked fatty acyl chain whose quality depends on the membrane type. The effect of length and unsaturation of the N-acyl chain on the mixing behavior of different sphingolipids has scarcely been studied and in this work this issue is addressed employing Langmuir monolayers at the air-water interface, in order to assess the surface mixing in binary mixtures of different species of sphingomyelins and ceramides. The dependence on the monolayer composition of the mean molecular area, perpendicular dipole moment, domain segregation and surface topography, as well as the film elasticity and optical thickness was studied. The results indicate that composition-dependent favorable interactions among sphingomyelin and ceramide occur as a consequence ofcomplementary lateral packing and increased acyl chain ordering; the phase state of the  components appears as a major factor determining miscibility among sphingomyelins and ceramides even in cases where the lipids have a considerable hydrocarbon chain length mismatch.