The gel to liquid-crystal phase transition of different phosphatidylcholine liposomes has been studied by differential scanning calorimetry in the presence of divalent cations (Ca2+, Zn2+, Cu2+) of relevant biological interest. The calorimetric experiments were carried out at different ion concentrations. The effects on the transition temperature were observed as shifts in the calorimetric peaks towards higher values, even if their magnitudes were lower than those reported for charged lipids. A very small effect on the enthalpy variation was shown to be associated with this transition. We tried to relate the modifications of the thermotropic behaviour of the examined phospholipids with the ionic radius, taking into account also the area per molecule occupied by phosphatidylcholines; the calorimetric results support the idea that the ion-lipid interaction with formation of the complexes is a function of the area occupied by the lipid head group.
A CALORIMETRIC STUDY OF THE INFLUENCE OF DIVALENT-CATIONS ON THE THERMOTROPIC BEHAVIOR OF SOME PHOSPHATIDYLCHOLINES
CASTELLI, Francesco;
1991-01-01
Abstract
The gel to liquid-crystal phase transition of different phosphatidylcholine liposomes has been studied by differential scanning calorimetry in the presence of divalent cations (Ca2+, Zn2+, Cu2+) of relevant biological interest. The calorimetric experiments were carried out at different ion concentrations. The effects on the transition temperature were observed as shifts in the calorimetric peaks towards higher values, even if their magnitudes were lower than those reported for charged lipids. A very small effect on the enthalpy variation was shown to be associated with this transition. We tried to relate the modifications of the thermotropic behaviour of the examined phospholipids with the ionic radius, taking into account also the area per molecule occupied by phosphatidylcholines; the calorimetric results support the idea that the ion-lipid interaction with formation of the complexes is a function of the area occupied by the lipid head group.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
