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 Å) 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 Å 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