Creation of Cross-Linked Bilayer Membranes That Can Incorporate Membrane Proteins from Oligo-Asp-Based Peptide Gemini Surfactants

摘要

We designed novel bilayer-forming amphiphiles based on the cyclic oligo-Asp-based peptide gemini (PG) surfactants cr-D_2C_(12) and cr-D_3C_(12), which consist of -Cys(Asp)_nCys- (n = 2 or 3) as a core peptide and two Cys residues containing a dodecylamidomethyl group. Dynamic light scattering and transmission electron microscopy measurements revealed the formation of spherical bilayer membranes that could incorporate the light-harvesting antenna complex 2 (LH2) from Rhodopseudomonas acidophila. Furthermore, this proteoliposome-like conjugate could be assembled onto cationized glass and mica to form planar bilayer membranes incorporating LH2. Using atomic force microscopy, we observed LH2 protruding (ca. 1.2-1.5 nm) from flat terraces of the planar bilayer membranes formed from cr-D_2C_(12) or cr-D_3C_(12). Thus, our designed PG surfactants are a new class of bilayer-forming amphiphiles that may be applied to the study of various membrane proteins.