Dynamics of Bilayer Interactions at the Air-Water Interface

Abstract

A novel supported bilayer system at the air-water interface has been developed for use in synchrotron X-ray scattering experiments in order to drastically increase signal to noise ratio. This system gives a significant resolution improvement comparing to more traditional solid-supported bilayer system and is better suited for specular X-Ray reflectivity and grazing incidence X-ray off-specular scattering. Using this system we have successfully characterized anionic bilayers mimetic of Gram-positive bacterial membranes interacting with engineered biomimetic oligomers (peptoids), zwitterionic bilayers interacting with human islet amyloid polypeptide (IAPP), and insertion differences between zwitterionic membranes with and without cholesterol and the glycoprotein-41 subunit fragment of the viral envelope glycoprotein-160. Results from anionic and net neutral bilayers correspond to previous studies on monolayer insertion studies, where peptoid ML 2-6 acts by associating throughout the lipophilic regions and zwitterionic bilayers without cholesterol were completely penetrated by the GP-41 fusion peptide. Resolution of the dynamic formation of a zwitterionic lipid bilayer system in minute scale time resolution via Grazing Incidence X-Ray Off-Specular Scattering (GIXOS) was also observed, and found to be in agreement with the proposed mechanisms associated with vesicle fusion on a solid support.