Pattern Characterization in Lipid Bilayers

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Phospholipid bilayers have become a popular topic of study in recent years due to their importance in biological systems. Membranes on organellar and cellular scales consist of lipid mixtures which include proteins whose properties play important roles in domain formation and intercellular chemistry. Biologically relevant concentrations of lipids form a number of heterogeneous shapes and patterns including stripes and circular phases. Due to their small size and short lifespan owing to the fluctuating nature of the bilayer system, ordered domains of lipids are difficult to study experimentally. Thus, simulation has become an invaluable tool for traversing the biological energy landscape. The majority of studies on bilayer systems have focused on local molecular dynamics in full atomistic detail. This restricts the size and time scales of simulations such that no meaningful information regarding phase behavior can be obtained. Coarse-graining (CG) techniques that average some of the properties of neighboring atoms have been developed so that greater timescales and numbers of particles can be simulated. Studying phase changes of a lipid bilayer system involves sorting through vast amounts of data making it difficult to extract meaningful information and to pinpoint mechanisms. Our group uses Karhunen-Loeve Expansion, a variant of Principal Components Analysis, to study the spatio-temporal evolution of the bilayer properties and the associated patterns.

Our collaborator in this project is Professor R. Faller (UC Davis).

Related Publications

• Switzer, J., S. Bennun-Serrano, A. Palazoglu, M.L. Longo, R. Faller, “Karhunen-Loeve Analysis for Pattern Description in Phase Separated Lipid Bilayer Systems,” J. Chem. Phys., 124, #234906 (2006).