21 research outputs found
2-state and continuous phase-transitions in lipid bilayers - a time-resolved x-ray-diffraction study
Structural rearrangements during crystal liquid-crystal and gel liquid-crystal phase-transitions in aqueous dispersions of dipalmitoylphosphatidylethanolamine - a time-resolved x-ray-diffraction study
Mechanism and kinetics of the subtransition in hydrated L-dipalmitoylphosphatidylcholine
Sugars favor formation of hexagonal (Hii) phase at the expense of lamellar liquid-crystalline phase in hydrated phosphatidylethanolamines
Structure and phase-behavior of hydrated mixtures of L-dipalmitoylphosphatidylcholine and palmitic acid - Correlations between structural rearrangements, specific volume changes and endothermic events
Lamellar gel-lamellar liquid-crystal phase-transition of dipalmitoylphosphatidylcholine multilayers freeze-dried from aqueous trehalose solutions
Effect of proline and dimethyl-sulfoxide on phase-behavior of hydrated and freeze-dried phosphatidylcholine bilayers
Cubic phases in membrane lipids
On the basis of data obtained by time-resolved X-ray diffraction, we consider in the present article the occurrence and formation pathways of inverted bicontinuous cubic phases, or bilayer cubic phases, Q (II)(B) , in diluted dispersions of lipids representing major biomembrane lipid classes [phosphatidylethanolamines (PEs), mixtures of PEs and phosphatidylcholines (PCs) with other lipids, glycolipids]. We show that Q (II)(B) formation proceeds much more easily upon cooling from the H(II) phase than upon heating or isothermal conversion from the L(α) phase, thus identifying an indirect but faster route for Q (II)(B) phase induction in lipids. The data collected consistently show that the ability to convert into cubic phase upon temperature cycling appears to be a general property of all lipids exhibiting an L(α) ↔ H(II) phase transition. Admixtures of charged phospholipids, both anionic and cationic, strongly facilitate Q (II)(B) formation in PEs. Their effect may be attributed to increased electrostatic repulsion between the lipid bilayers that reduces the unbinding energy and facilitates the dissipation of the L(α) phase required for its conversion into bilayer cubic phase