Infrared spectroscopy of supported lipid monolayer, bilayer, and multibilayer membranes.

Cecropin A was examined in supported monolayer, bilayer, and multibilayer lipid membranes using attenuated total internal reflection Fourier-transform infrared spectroscopy. The spectral features provide an abundance of information about the conformation and orientation of the peptide, as well as about the effects of the peptide on lipid order. In this case, they serve to contrast results from the three preparations. The results of monolayer and bilayer studies are generally similar, although differences in the nature of the membranes appear to cause minor changes in the conformation and orientation of the peptide. The results of the multibilayer studies are different in many respects from those of the monolayer and bilayer studies, suggesting that fundamentally different peptide-lipid interactions occur in multibilayers.