Neutron Diffraction Studies on the Location of Water in Lecithin Bilayer Model Membranes

Lamellar neutron diffraction from oriented multilayers of hydrated dipalmitoyl lecithin was phased by isomorphous H₂O-D₂O exchange and swelling techniques. Bound water sites were located in the polar head group region of the bilayer profile. A 6-Å resolution structure based on the neutron scattering density profile is proposed for the bilayer. It is consistent with the electron density profile from x-ray diffraction.