The Partitioning Behavior of Free Amino Acids into Lipid Membranes

Abstract

In an attempt to better understand how proteins interact with membrane environments, it is useful to determine how individual amino acids interact with and incorporate into lipid bilayers. Previous work has shown how small polarizable molecules and ions affect the interactions between lipid membranes. This process involves a combination of van der Waals attraction, electrostatic repulsion and other interfacial contributions [1, 2]. We use a combination of small angle x-ray scattering, NMR spectroscopy and osmotic stress to study how water soluble amino acids change the interaction between lipid bilayers. Experiments containing various amino acids under a range of osmotic pressures were performed to determine the changes in the equilibrium spacing of multilamellar lipid vesicles (MLVs). NMR measurements of free amino acids in the presence of MLVs allow us to characterize their partitioning behavior. The combination of these techniques gives us a detailed description of how amino acids such as lysine, glycine, alanine, arginine, serine and valine interact with neutral phosphatidylcholine lipid bilayers.[1] Koerner et al., Biophys. J. 2011, [2] Johnson et al., Langmuir 2014.