The physical state of quick-frozen membranes and lipids |
| |
Authors: | Donald L Melchior Edward P Bruggemann Joseph M Steim |
| |
Institution: | 1. Department of Biochemistry, University of Massachusetts Medical School, Worcester, MA 01605 USA;2. Department of Chemistry, Brown University, Providence, RI 02912 U.S.A. |
| |
Abstract: | Lipid bilayers and biomembranes produce nearly identical calorimeter scans regardless of whether they are slowly cooled under near-equilibrium conditions or rapidly frozen at rates used in freeze-fracture electron microscopy. Except for the melting of ice at 273 K, for both cooling regimens no significant thermal events occur from 100 K to the usual gel to liquid crystal transition. The gel to liquid crystal transition itself is somewhat altered by rapid cooling when bilayers contain mixed lipid species. Combined with X-ray diffraction studies, the results indicate that quickly frozen bilayers are crystalline, but that the crystalline domains are quite small or otherwise disordered. In contrast to the behavior of lipids in bilayers, hexagonal-phase calcium cardiolipid easily forms a glass upon cooling. |
| |
Keywords: | Lipid bilayer Membrane structure Rapid freezing X-ray crystallography Liquid crystal Phase transition Differential scanning calorimetry |
本文献已被 ScienceDirect 等数据库收录! |
|