On the design of supramolecular assemblies made of peptides and lipid bilayers.

Peptides confer interesting properties to materials, supramolecular assemblies and to lipid membranes and are used in analytical devices or within delivery vehicles. Their relative ease of production combined with a high degree of versatility make them attractive candidates to design new such products. Here, we review and demonstrate how CD- and solid-state NMR spectroscopic approaches can be used to follow the reconstitution of peptides into membranes and to describe some of their fundamental characteristics. Whereas CD spectroscopy is used to monitor secondary structure in different solvent systems and thereby aggregation properties of the highly hydrophobic domain of p24, a protein involved in vesicle trafficking, solid-state NMR spectroscopy was used to deduce structural information and the membrane topology of a variety of peptide sequences found in nature or designed. (15)N chemical shift solid-state NMR spectroscopy indicates that the hydrophobic domain of p24 as well as a designed sequence of 19 hydrophobic amino acid residues adopt transmembrane alignments in phosphatidylcholine membranes. In contrast, the amphipathic antimicrobial peptide magainin 2 and the designed sequence LK15 align parallel to the bilayer surface. Additional angular information is obtained from deuterium solid-state NMR spectra of peptide sites labelled with (2)H3-alanine, whereas (31)P and (2)H solid-state NMR spectra of the lipids furnish valuable information on the macroscopic order and phase properties of the lipid matrix. Using these approaches, peptides and reconstitution protocols can be elaborated in a rational manner, and the analysis of a great number of peptide sequences is reviewed. Finally, a number of polypeptides with membrane topologies that are sensitive to a variety of environmental conditions such as pH, lipid composition and peptide-to-lipid ratio will be presented.