Mechanisms of Peptide-Induced Pore Formation in Lipid Bilayers Investigated by Oriented 31P Solid-State NMR Spectroscopy
Figure 6
Model of peptide interactions with the lipid membrane compatible with data from oriented-sample solid-state NMR 31P spectra.
The lipids are illustrated by circles with the radial line illustrating the orientation of the 31P head group. (a) Pure bilayers display a single sharp resonance at around 30 ppm. (b) At low peptide concentrations, weak interactions between peptide and lipids induce a slight disorder causing the 31P resonance to shift to lower values. (c) The peptide insertion involves lipids that change orientation with reduced diffusion as a consequence. This gives rise to a peak at approximately −15 ppm. (d and e) The last step in the method of action of the peptide is the penetration of the lipids and disruption of the bilayer. Alamethicin forms barrel-stave channels without significant perturbation of the lipid (d), while novicidin creates toroidal pores in the lipids (e).