| Abstract
| - Using a combination of fluorescence correlation and infrared absorption spectroscopies, wecharacterize lipid lateral diffusion and membrane phase structure as a function of protein binding to themembrane surface. In a supported membrane configuration, cholera toxin binding to the pentasaccharaideheadgroup of membrane-incorporated GM1 lipid alters the long-range lateral diffusion of fluorescently labeledprobe lipids, which are not involved in the binding interaction. This effect is prominently amplified near thegel-fluid transition temperature, Tm, of the majority lipid component. At temperatures near Tm, large changesin probe lipid diffusion are measured at average protein coverage densities as low as 0.02 area fraction.Spectral shifts of the methylene symmetric and asymmetric stretching modes in the lipid acyl chain confirmthat protein binding alters the fraction of lipid in the gel phase.
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