The hydrophobic mismatch determines the miscibility of ceramides in lipid monolayers.
The organization of lipids within membranes strongly depends on the interaction with other lipid and protein molecules. Sphingolipids comprise a structurally diverse family, the ceramides being some of the simplest members. Although small chemical modifications of ceramide structure, such as varying the N-acyl chain length, lead to a complex polymorphism of this lipid, only long acyl chain ceramides have usually been studied and their properties became a putative hallmark for all ceramides. In this work, we studied the mixing behavior of C10:0 Cer, which has the N-acyl chain shorter than that of the sphingosine acyl chain and displays an expanded to condensed phase transition at 25 mN m(-1) at 24 °C, with ceramides N-acylated with longer fatty acyl chains C12:0, C14:0 and C18:0. The N-acyl chain length determined the miscibility of ceramides in Langmuir monolayers, as it was ascertained by the dependence of the mean molecular area, perpendicular dipole moment, surface topography and film thickness with the mixture composition. We found that, as the hydrophobic mismatch in ceramides increased complete miscibility, partial or complete immiscibility can occur.
Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
Fernando
F
Dupuy
Bruno
B
Maggio
D002518:Ceramides / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008055:Lipids / Q000737:chemistry*; D044367:Phase Transition; D013110:Sphingosine / Q000737:chemistry; D013499:Surface Properties; D053835:Unilamellar Liposomes / Q000737:chemistry
D002518:Ceramides; D008055:Lipids; D053835:Unilamellar Liposomes; D013110:Sphingosine