Models of stratum corneum intercellular membranes: the sphingolipid headgroup is a determinant of phase behavior in mixed lipid dispersions.
During formation of the intercellular membranes of mammalian stratum corneum, sphingomyelin and glucosylceramide are converted enzymatically to ceramide. To model in isolation the possible effect of such a lipid modification on the phase behavior of the ensemble, we used proton and deuterium nuclear magnetic resonance to compare an equimolar dispersion of bovine brain sphingomyelin, cholesterol, and perdeuterated palmitic acid (at pH 6.2), with an equivalent dispersion in which bovine brain ceramide was substituted for sphingomyelin. While the sphingomyelin dispersions remain in a homogeneous fluid lamellar phase from 20-75 degrees C under these conditions, those containing ceramide display complex polymorphism.
Thewalt
J
J
Dept. of Physics, University of British Columbia, Vancouver, Canada.
Kitson
N
N
Araujo
C
C
MacKay
A
A
Bloom
M
M
D002518:Ceramides / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry; D004817:Epidermis / Q000502:physiology; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D008560:Membrane Fluidity; D008567:Membranes, Artificial; D008956:Models, Chemical; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000737:chemistry; D013109:Sphingomyelins / Q000737:chemistry*
D002518:Ceramides; D008567:Membranes, Artificial; D010169:Palmitic Acids; D013109:Sphingomyelins; D019308:Palmitic Acid; D002784:Cholesterol