Coupling Optical and Electrical Measurements in Artificial Membranes: Lateral Diffusion of Lipids and Channel Forming Peptides in Planar Bilayers.
Planar lipid bilayers (PLB) were prepared by the Montal-Mueller technique in a FRAP system designed to simultaneously measure conductivity across, and lateral diffusion of, the bilayer. In the first stage of the project the FRAP system was used to characterise the lateral dynamics of bilayer lipids with regards to phospholipid composition (headgroup, chain unsaturation etc.), presence of cholesterol and the effect of divalent cations on negatively-charged bilayers. In the second stage of the project, lateral diffusion of two fluorescently-labelled voltage-dependent pore-forming peptides (alamethicin and S4s from Shaker K(+) channel) was determined at rest and in the conducting state. This study demonstrates the feasibility of such experiments with PLBs, amenable to physical constraints, and thus offers new opportunities for systematic studies of structure-function relationships in membrane-associating molecules.
UMR 6522 CNRS-Université de Rouen. Bd M. de Broglie, 76821 Mont-Saint-Aignan. France.School of Biological Sciences. University of East Anglia, Norwich NR4 7TJ, England. Present Address: The Johnson Research Foundation for Molecular Biophysics and Structural Biology, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059. USA.Institute of Food Research. BBSRC, Colney Research Park, Norwich NR4 7UA. England. herve.duclohier@univ-rouen.fr
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