title: Molecular packing in sphingomyelin bilayers and sphingomyelin/phospholid mixtures.
abstract: The molecular packing properties of sphingomyelin (SM) from egg yolk were studied. The influence of the spontaneous curvature of SM on the phase behaviour of SM/dodecane/water systems was investigated. A comparison was made to a previous study by Lindblom et al. (Liq. Cryst. 3 (1988) 783), of the phase behaviour of dipalmitoylphosphatidylcholine (DPPC)/dodecane/water systems, where a reversed hexagonal liquid crystalline was shown to form at high water contents (60-80%, w/w). In contrast, SM/dodecane/water systems mainly maintained a lamellar liquid crystalline phase at all compositions and temperatures >35 degrees C. This suggests that the spontaneous curvature of SM is larger than for DPPC. To further examine the packing properties of SM and DPPC, the phase behaviour of SM/dioleoylphosphatidylethanolamine (DOPE)/water and DPPC/DOPE/water systems were investigated. Aqueous dispersions of DOPE normally form a reversed hexagonal liquid crystalline phase, while an isotropic phase was formed at small additions (20 mol.%) of SM or DPPC and a lamellar liquid crystalline phase was maintained at higher fractions (>35 mol.%) of SM or DPPC.
authors.affiliation: Department of Chemistry, Biophysical Chemistry, Umeå University, SE-90187 Umeå, Sweden. tomas.bystrom@chem.umu.se
authors.forename: Tomas
authors.initials: T
authors.lastname: Byström
authors.forename: Göran
authors.initials: G
authors.lastname: Lindblom
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D013109:Sphingomyelins / Q000737:chemistry*
chemical_list: D000473:Alkanes; D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; C007548:n-dodecane; C094877:dioleoyl phosphatidylethanolamine; D015060:1,2-Dipalmitoylphosphatidylcholine