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Curvature Effect on the Structure of Phospholipid Bilayers*, Norbert Kučerka 1, Jeremy Pencer1, Jonathan Sachs2, John Nagle3, John Katsaras1 , 1National Research Council , 2University of Minnesota, 3Carnegie Mellon University High-resolution small-angle X-ray scattering (SAXS), complemented by small-angle neutron scattering (SANS) and dynamic light scattering (DLS) experiments, was used to study the effect of curvature on the bilayer structure of varying diameter (600 1800 ) dioleoyl-phosphatidylcholine (DOPC) unilamellar vesicles (ULVs). Unilamellarity of large DOPC ULVs was achieved by the addition of small amounts (up to 4 mol %) of the charged lipid, dioleoyl-phosphatidylserine (DOPS). In all cases, both the inner and outer leaflets of DOPC bilayers were found to be indistinguishable. However, 1220 diameter pure DOPS ULVs formed asymmetric bilayers whose structure can most likely be rationalized in terms of geometrical constraints coupled with electrostatic interactions, rather than curvature alone.


* This work is being supported by NIST/NSF/CNBT