Chemically well-defined liposomes have long served as model systems for the controlled study of lipid bilayer properties, and the behavior of membrane-associated proteins. Despite the chemical control over these model systems the ability to measure fundamental physical behaviors has proven exceedingly difficult if not at all. Recently, we have made significant progress on the preparation and characterization of asymmetric liposomes.<br/><br/>Our new methodology for the construction of free floating asymmetric vesicles was optimized for the construction of stable, and stress-free 100 nm isotopically asymmetric vesicles. More importantly, we have developed new analytical procedures allowing for precise measurement of the composition of each leaflet of the asymmetric bilayer. Together, these improvements in preparation and characterization methods constitute a significant step toward the realization of a longstanding goal of membrane biophysics, and should facilitate the rapid advancement of model membrane studies.<br/><br/>Among these advancements is the new ability to examine lipid transverse diffusion, commonly known as flip/flop. Lipid flip/flop rates, which have historically been challenging to obtain, can now be accurately determined using our novel high-yield method for generating isotopically asymmetric vesicles, and the methodology for the robust quantification of their structure and asymmetry. Here we begin to investigate long-standing questions regarding the influence of bilayer structure and composition on flip/flop rates in stress-free vesicle systems.

Stress-free asymmetric lipid vesicles for the study of transverse lipid motion

251st National Meeting (2016)

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