Peptide Aggregation in Lipid Bilayers — Is the Peptide Really in the Striated Domains?

Abstract

In order to elucidate the structure and function of biomembranes, it is useful to investigate interactions between lipids and proteins, which are the main building blocks of all biological membranes. Supported lipid/peptide bilayers, which can be prepared, using established protocols, are a widely used model system to perform these investigations. Atomic Force Microscopy (AFM) offers a unique possibility to investigate these supported bilayers under physiological conditions (in water environment). We (H. Rinia et al., Biochemistry, 2000, 39, 5852-5858) previously found that synthetic transmembrane peptides self organize in highly characteristic striated domains in supported gel state bilayer. The precise morphology of the domains depends on the type of peptide and lipid. In the present study we attempt to localize the peptide in these domains by AFM using Au particles (app. 10 nm.) and thiol containing peptides. These peptides were also found to form striated domains. We also showed by Dynamic Light Scattering experiments that thiol group of a peptide, incorporated in a bilayer is available for reaction with gold. After addition of the gold particles over the supported bilayer we observe with contact mode AFM the presence of gold particles predominantly over domains and cracks, connecting them.