Lipid membrane domain formation and alamethicin aggregation studied by calorimetry, sound velocity measurements, and atomic force microscopy |
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Authors: | Oliynyk Vitaliy Jäger Markus Heimburg Thomas Buckin Vitaly Kaatze Udo |
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Institution: | 1. Complex Fluids Group, Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany;2. Membrane Biophysics Group, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark;3. School of Chemistry &; Chemical Biology, University College Dublin, Dublin 4, Ireland |
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Abstract: | An experimental study of phosphocholine membranes made from one lipid, from mixtures of DPPC and DLPC, and also from lipids and small amounts of alamethicin is presented. We used atomic force microscopy to investigate the spatial organization and structure of lipid domains and also of the defects induced by the peptide. Alamethicin was found to alter the state of lipids in the gel state in a way that domains of fluid lipids are formed close to the defects. Differential calorimetry revealed phase characteristics of the lipid mixtures and the effect of small amounts of alamethicin on the phase behavior. It was also shown that the sound velocity profiles of the membranes suspensions can be well calculated from the heat capacity traces of the samples. This result confirms the correlation between the mechanical properties and the specific heat of membrane systems. |
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Keywords: | Lipid membranes Alamethicin Peptide pores Atomic force microscopy Sound velocity Differential scanning calorimetry |
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