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Center for Nonlinear Studies |
Lipids are an important type of biomolecule that make up cellular membranes and are involved with cell signaling and many biological functions. Characterizing lipid properties is challenging because lipid bilayers are thin hydrophobic sheets (~3 nm), they are soft-condensed matter, and collective interactions are often crucial. I use molecular dynamics computer simulations to study lipid membranes. Free energy calculations are used to probe the stability and thermodynamics of lipids in two different problems: cholesterol-lipid interactions and fatty acid pKa calculations. Poly-unsaturated lipids are shown to prefer low cholesterol lipid bilayers due to unfavorable packing in the ordered bilayers. For the fatty acid calculations, I will show that the pKa for a long chain fatty acid shifts to higher values in lipid bilayers and micelles compared to water, the pKa depends strongly on the local chemical environment and is anti-cooperative. Molecular driving forces for cholesterol-lipid mixing and fatty acid protonation are presented.
Host: Sandrasegaram Gnanakaran