Abstract
We have investigated the structure of lipid bilayers containing varied molar ratios of different lipids and the antimicrobial peptides magainin and alamethicin. For this structural study, we have used x-ray reflectivity on highly aligned solid-supported multilamellar lipid membranes. The reflectivity curves have been analyzed by semi-kinematical reflectivity theory modeling the bilayer density profile rho(z). Model simulations of the reflectivity curves cover a large range of vertical momentum transfer q(z), and yield excellent agreement between data and theory. The structural changes observed as a function of the molar peptide/lipid concentration P/L are discussed in a comparative way.