Modulation by gangliosides of the lamellar-inverted micelle (hexagonal II) phase transition in mixtures containing phosphatidylethanolamine and dioleoylglycerol.
We studied the effect of gangliosides GD1a and GM1 on the lamellar-to-hexagonal II phase transition of mixtures of dioleoylphosphatidylethanolamine/dioleoylphosphatidyl choline, 3:1, and of transphosphatidylated phosphatidylethanolamine with dioleoylglycerol by high-sensitivity differential scanning calorimetry, 31P-NMR, and pyrene fluorescence of a phosphatidylcholine probe. Gangliosides had a dual effect. Below 1 mol % ganglioside the hexagonal II phase transition was affected but still occurred at lower temperature than in the absence of gangliosides. The presence of between 1 and 2 mol % gangliosides increased the temperature for formation of the hexagonal II phase and progressively decreased its cooperativity. Above 3 mol % gangliosides totally inhibited the formation of both the temperature-induced and composition-induced hexagonal phase, probably by opposing the geometric distortions necessary for the inverted micellar structures.
Perillo
M A
MA
Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0614.
Scarsdale
N J
NJ
Yu
R K
RK
Maggio
B
B
D004075:Diglycerides; D005732:Gangliosides / Q000737:chemistry*; D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010758:Phosphorus; D013816:Thermodynamics
D004075:Diglycerides; D005732:Gangliosides; D008051:Lipid Bilayers; D008823:Micelles; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C021298:ganglioside, GD1a; D010758:Phosphorus; C020888:1,2-dielaidoylphosphatidylethanolamine; C017251:1,2-oleoylphosphatidylcholine; C013965:diolein