| Popis: |
The interaction of Asolectin vesicles with an anionic (NaDodSO 4 ), cationic (DodPyCl), and nonionic (DeDPO) surfactant was investigated by titration calorimetry at 25°C. An enthalpy change of about −2.0 kcal/mole was found for what appears to be a rapid penetration of all three of the surfactants into the vesicle bilayer. The stoichiometry for saturation of the vesicles was about 0.06 g surfactant/g of phospholipid in each case. Only NaDodSO 4 , exhibited evidence of a lamellar-micelle phase transition, which was complete at a stoichiometry of 0.24 g of surfactant/g of phospholipid. The free energy changes for interaction of the ionic surfactants were more negative than for DeDPO. The entropy change was much less for the binding of DeDPO to the vesicles (7.7 cal/moledeg) than for micelle formation (17.4 cal/mole-deg). The nonionic surfactant, Lubrol WX, did not have a measurable enthalpy of interaction with the vesicles under the conditions employed. |
