Transition of lipid phase in aqueous dispersions of diacylglyceryltrimethylhomoserine.

The phase transition in the lipid phase of aqueous dispersions of diacylglyceryltrimethylhomoserine (DGTS) was measured by fluorescence depolarization of parinaric acid and differential scanning calorimetry. In both techniques, the phase transition temperatures (Tm) of 1-palmitoyl-2-stearoyl DGTS and of 1,2-distearoyl DGTS were 53 and 59 degrees C, respectively. Each of these Tm values was significantly higher than the Tm value of phosphatidylcholine with an identical combination of fatty acids. This suggests that the intermolecular interactions of DGTS molecules are slightly different from those of phosphatidylcholine molecules.