  We adapted the highly successful scattering density profile (SDP) model,
which is used to jointly analyze small angle x-ray and neutron scattering data
from unilamellar vesicles, for use with data from fully hydrated, liquid
crystalline multilamellar vesicles (MLVs). By using a genetic algorithm, this
new method is capable of providing high resolution structural information, as
well as determining bilayer elastic bending fluctuations from standalone x-ray
data. Important structural parameters, such as bilayer thickness and area per
lipid were determined for a series of saturated and unsaturated lipids, as well
as binary mixtures with cholesterol. Results are in good agreement with
previously reported SDP data, which used both neutron and x-ray data. The
addition of deuterated and non-deuterated MLV neutron data to the analysis
improved lipid backbone information, but did not improve, within experimental
uncertainties, the structural information regarding bilayer thickness and area
per lipid.
