Abstract
We have studied some physical properties of mixed phosphatidylcholine (SOPC)-phosphatidylserine (SOPS) vesicles. In a previous work (Paredes et al. in J Biol Phys 32:177-181, 2006) it was shown that the shape of the vesicles depends on the SOPC:SOPS composition, and that coiled cylindrical vesicles exist in samples with low SOPS contents. In this work, we further studied the same system of mixed vesicles. Differential scanning calorimetry (DSC) experiments displayed peaks characteristic of lipid mixing in the liquid state, ruling out a possible phase transition as an explanation of vesicle coiling. In addition, small-angle X-ray scattering (SAXS) experiments allowed us to estimate the periodicity distance inside the vesicles. This distance is d ≈ 60 Å, as revealed by the Bragg peaks observed in the experiments. Finally, the coiling transition of a cylindrical vesicle was observed under solvent flow. This observation indicates that the vesicle coiling reported previously for this system (Paredes et al. in J Biol Phys 32:177-181, 2006) does not depend on the SOPC:SOPS composition alone, but also on mechanical perturbations during the preparation steps.
| Original language | English |
|---|---|
| Pages (from-to) | 283-289 |
| Number of pages | 7 |
| Journal | Lipids |
| Volume | 44 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2009 |
Bibliographical note
Funding Information:Acknowledgments G.P.-Q. acknowledges a fellowship from Conacyt-Mexico. A.M. acknowledges financial support from Cona-cyt-Mexico (grants 32105E and 0074) and ANUIES-ECOS (MOOP03). H.A.-E. and G.P.-Q. thank Dennis Discher for allowing us to use his laboratory where initial experiments were carried out. We thank Raymond Ober and Ricardo López-Esparza for collaboration in the SAXS experiments.
Keywords
- Biological membranes
- Phospholipids
- SOPC
- SOPS
- Vesicle coiling
- Vesicles