Electron cryo-microscopy of vitrified bulk biological specimens: ideal and real structures of water-lipid phases.
Lipid-water mixtures were studied by X-ray cryo-diffraction in order to assess the structural changes during freezing. We show that the water of aqueous lipid phases, in the concentration range of 10-30% (water weight/total weight), is vitrified by high-pressure freezing. Vitrified lipid phases can be cryo-sectioned and imaged by electron cryo-microscopy. Both the ideal or average and the real or local structures of the lipid mixtures can be studied at a resolution better than 2 nm. While the average structure of the lipid phases is in good agreement with that determined by X-ray diffraction, the local structure reveals features that might play an important role in the function of biological membranes such as in endo- and exocytosis.
Erk
I
I
Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Yvette, France.
Michel
M
M
Lepault
J
J
D005615:Freezing; D005629:Frozen Sections; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000032:analysis*; D008854:Microscopy, Electron; D011312:Pressure; D014867:Water; D014961:X-Ray Diffraction
D008051:Lipid Bilayers; D008055:Lipids; D014867:Water