Physical properties of single phospholipid bilayers adsorbed to micro glass beads. A new vesicular model system studied by 2H-nuclear magnetic resonance (original) (raw)

Abstract

Spherical supported vesicles (SSVs), a new model system consisting of single dimyristoyl phosphatidylcholine (DMPC) bilayers adsorbed to spherical glass beads with a narrow size distribution, were prepared at two different sizes (0.5 and 1.5 microns) and their physical properties were studied by deuterium nuclear magnetic resonance (2H-NMR). Such SSV samples can be prepared at any desired size between 0.3 and 10 microns. The 2H-NMR measurements provide evidence for a strong dependence of the spectra and the transverse relaxation times on the curvature of the SSVs in a diameter range between 0.5 and 1.5 microns. For larger SSVs (1.5 microns diameter) their powder spectra and their calculated oriented spectra are similar to those obtained for multilamellar dispersions of DMPC-d54. The lineshape of the smaller SSVs exhibits a temperature dependence which is not found in multilamellar samples. The SSVs are stable in the liquid crystalline phase over days but irreversibly change to multilamellar vesicles in the gel state. The average thickness of the water layer between the single bilayer and the glass bead surface was estimated by 1H-NMR to e 17 +/- 5 A.

357

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bayerl T. M., Köchy T., Brückner S. On the modulation of a high-enthalpy pretransition in binary mixtures of DMPC and DMPG by polar headgroup interaction. Biophys J. 1990 Mar;57(3):675–680. doi: 10.1016/S0006-3495(90)82587-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bayerl T. M., Thomas R. K., Penfold J., Rennie A., Sackmann E. Specular reflection of neutrons at phospholipid monolayers. Changes of monolayer structure and headgroup hydration at the transition from the expanded to the condensed phase state. Biophys J. 1990 May;57(5):1095–1098. doi: 10.1016/S0006-3495(90)82628-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Davis J. H. Deuterium magnetic resonance study of the gel and liquid crystalline phases of dipalmitoyl phosphatidylcholine. Biophys J. 1979 Sep;27(3):339–358. doi: 10.1016/S0006-3495(79)85222-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Davis J. H. The description of membrane lipid conformation, order and dynamics by 2H-NMR. Biochim Biophys Acta. 1983 Mar 21;737(1):117–171. doi: 10.1016/0304-4157(83)90015-1. [DOI] [PubMed] [Google Scholar]
  5. McConnell H. M., Watts T. H., Weis R. M., Brian A. A. Supported planar membranes in studies of cell-cell recognition in the immune system. Biochim Biophys Acta. 1986 Jun 12;864(1):95–106. doi: 10.1016/0304-4157(86)90016-x. [DOI] [PubMed] [Google Scholar]
  6. Seelig J., Seelig A. Lipid conformation in model membranes and biological membranes. Q Rev Biophys. 1980 Feb;13(1):19–61. doi: 10.1017/s0033583500000305. [DOI] [PubMed] [Google Scholar]