Solid-state 19 F-NMR analysis of peptides in oriented biomembranes

Abstract

Solid-state 19 F-NMR is a powerful method used to study membrane-active peptides under quasi-native conditions in lipid bilayers. As shown in this chapter, it is possible to determine the conformation, orientation, dynamics, and aggregation behavior of peptides in membranes. Compared with other nuclei, 19 F provides a stronger signal, thus making it possible to study peptides at low concentrations (at peptide-to-lipid molar ratios as low as 1:3000) and to determine long distances between two labels (up to 11 Å in fluid bilayers). The method is well established and has been applied to a number of antimicrobial, cell-penetrating, and fusogenic peptides that form a-helices, ß-sheets, or more irregular structures, and the results are summarized here. Several new 19 F-labeled amino acids that have been recently introduced are described. With these, it is now possible to replace not only hydrophobic but also polar or charged amino acids without significant perturbation, thus making solid-state 19 F-NMR a highly versatile tool for characterizing peptidelipid interactions.