Biochemistry · 1981 · 176 citations · 23 references
Natural SciencesBiophysicsChemistryLipid BiochemistryMembrane BiophysicsMolecular BiophysicsBiomolecular ThermodynamicsLipid Bilayer StructureLipid StructureMembrane Phase BehaviorMembrane ThermodynamicsPhase TransitionsChain PackingEnthalpyLipid Bilayer Phase BehaviorLiposomesMembrane Lipid Phase BehaviorPhase Behavior Of Lipid BilayersPhase Transition EnthalpyPhase Transition Temperature
The thermotropism of dipalmitoyllecithin in fully hydrated multilamellar dispersions has been reexamined by differential scanning calorimetry, X-ray diffraction, and 31P nuclear magnetic resonance. Apart from the well-known pretransition and main transition, there exists a third transition at about 11 degrees C with a transition enthalpy of approximately 3.7 kcal/mol. Both adjoining phases are lamellar, but they differ in the lateral acyl chain packing of the lecithin molecules and in the dynamics of the polar head groups. The kinetics of this third phase transition are extremely slow in comparison with those of the other two transitions.
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