Physical studies of phospholipids. VI. Thermotropic and lyotropic mesomorphism of some 1,2-diacyl-phosphatidylcholines (lecithins)

Dynamics of lipids in membranes: Heterogeneity and the role of cholesterol

“…It is also apparent that the shape of the phase transition endotherm alters. The transition changes to a highly cooperative phenomenon on hydration, consistent with laser-Raman evidence [11 ], and the increased enthalpy of the transition [3].…”

“…The temperatures at which the phase transitions occur are dependent upon the headgroup, the hydrocarbon chain length, and the degree and type of unsaturation present [1 ]. For the same headgroup and extent of hydration, lipids with more unsaturated chains have lower transition temperatures than more saturated ones [2], longer chains higher transition temperatures than shorter ones [3], and cis-unsaturated chains lower transition temperatures than trans-unsaturated ones [4].…”

“…The effect of water has also been shown to have a profound effect on the temperature and enthalpy of the gel ~ liquid crystal phase transition [3 ]. DSC curves of distearoyl phosphatidylcholine indicate that 10 moles of water per mole of lecithin are bound, i.e.…”

Does propofol alter membrane fluidity at clinically relevant concentrations? An ESR spin label study

“…The mixture was stirred for 5 min and the solvent was evaporated under vacuum. The formed lipid film was suspended in phosphate buffer solution pH 7.0 (1/15 M; Na 2 HPO 4 -KH 2 PO 4 , from Riedel-de Haën, Belgium) at a temperature above the DMPC phase-transition temperature (23.9°C), and stirred by vortex mixer in order to obtain large multilamellar vesicles (MLV) [20]. After this hydratation, five freeze-thaw cycles using liquid nitrogen were carried out to allow a better incorporation of the labelled stearic acid into the liposome phospholipid bilayer.…”

Phase behaviour of dehydrated phosphatidylcholines

“…Previous studies have demonstrated that saturated anhydrous phosphatidylcholines undergo several thermotropic transitions above their T m values and below the isotropic melts, which occurs at 230°C [7,8]. Chapman et al [7] were able to identify the existence of three liquid-crystalline phases at temperatures below the isotropic melt.…”