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Lamellar-phase polymorphism in interdigitated bilayer assemblies
J T Mason1, R E Cunningham, T J O'Leary
1Department of Cellular Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
Biochimica Et Biophysica Acta
|May 24, 1995
Summary
Low-temperature incubation transforms small liposomes of 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine (C(18)C(10)PC) into planar sheets, altering their gel-phase transition temperature. This reveals insights into phospholipid bilayer behavior and interdigitated phase transitions.
Area of Science:
- Biophysics
- Materials Science
- Physical Chemistry
Background:
- Phospholipid bilayers exhibit diverse phases influencing membrane properties.
- 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine (C(18)C(10)PC) forms mixed-interdigitated gel-phase bilayers.
- Liposome size and morphology can affect bilayer phase transitions.
Purpose of the Study:
- To investigate the thermotropic behavior of C(18)C(10)PC bilayers.
- To understand the structural basis for observed phase transitions.
- To explore the role of phospholipid geometry in interdigitated bilayer formation.
Main Methods:
- Differential scanning calorimetry (DSC) for phase transition analysis.
- Electron microscopy for structural characterization.
- Preparation and incubation of C(18)C(10)PC liposome suspensions.
Main Results:
- Freshly prepared C(18)C(10)PC liposomes show a single phase transition at 14.6°C.
- Low-temperature incubation (<2°C) induces an additional transition at 17.9°C.
- Liposomes <0.2 microns convert to planar lamellar sheets, responsible for the higher transition temperature.
Conclusions:
- Liposome size and morphology significantly impact the thermotropic behavior of C(18)C(10)PC bilayers.
- Planar lamellar sheets exhibit distinct phase transition properties compared to liposomes.
- Findings suggest reversibility of interdigitated gel to liquid-crystalline phase transitions is influenced by phospholipid structure and aggregation state.