Lipid membranes often contain negatively charged lipids such as phosphatidylserine, phosphatidylglycerol, phosphatidic acid, and gangliosides. The head groups of these lipids contain carboxylate and phosphate groups which can interact with cations and positively charged amino acids. Moreover, such lipids are often heavily regulated within cells and appear in much greater abundance in the membranes of particular organelles and even specific leaflets within these membranes. We have used a combination of spectroscopic techniques, microfluidic platforms, and planar supported bilayer architectures to study the chemical specificity of positively charged analytes with these moieties. Both thermodynamic data and the molecular level details of the systems are obtained. The results reveal that binding can not only be highly dependent on the specific chemistry of the ligand-receptor interactions, but also on the concentration of negatively charged lipids, the presence of additional uncharged lipids in the membrane and the chemical nature of the positively charged groups which are binding.  In fact, the specific chemistry of these interactions (hydrogen bonding, charge transfer, hydrophobic interactions, etc�) often dominates over generic electrostatic effects.

Interactions of peptides and ions with supported lipid bilayers

245th National Meeting (2013)

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