Small-angle x-ray scattering from lipid bilayers is well described by modified Caillé theory but not by paracrystalline theory.
X-ray scattering data at high instrumental resolution are reported for multilamellar vesicles of L alpha phase lipid bilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine at 50 degrees C under varying osmotic pressure. The data are fitted to two theories that account for noncrystalline disorder, paracrystalline theory (PT) and modified Caillé theory (MCT). The MCT provides good fits to the data, much better than the PT fits. The particularly important characteristic of MCT is the long power law tails in the scattering. PT fits (as well as ordinary integration with no attempt to account for the noncrystalline disorder) increasingly underestimate this scattering intensity as the order h increases, thereby underestimating the form factors used to obtain electron density profiles.
Zhang
R
R
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Tristram-Nagle
S
S
Sun
W
W
Headrick
R L
RL
Irving
T C
TC
Suter
R M
RM
Nagle
J F
JF
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D055592:Biophysical Phenomena; D001703:Biophysics; D003460:Crystallization; D003627:Data Interpretation, Statistical; D008051:Lipid Bilayers / Q000737:chemistry*; D008956:Models, Chemical; D012542:Scattering, Radiation; D014965:X-Rays
D008051:Lipid Bilayers; D015060:1,2-Dipalmitoylphosphatidylcholine