P. Balgavy et al., BILAYER THICKNESS IN UNILAMELLAR EXTRUDED EGG-YOLK PHOSPHATIDYLCHOLINE LIPOSOMES - A SMALL-ANGLE NEUTRON-SCATTERING STUDY, Acta physica slovaca, 48(4), 1998, pp. 509-533
Using the small-angle neutron scattering and the Kratky-Porod plot, th
e bilayer thickness d(L) = 41.7 +/- 0.3 Angstrom has been determined i
n unilamellar egg yolk phosphatidylcholine liposomes dispersed in heav
y water and prepared by extrusion through 500 Angstrom pores in polyca
rbonate filters. The peak-peak distance across the bilayer obtained fr
om the data of small-angle X-ray scattering on the liquid-crystalline
L-alpha phase of fully hydrated egg yolk phosphatidylcholine is 37.4 A
ngstrom less than or equal to d(PP) less than or equal to 38.1 Angstro
m. Using this value and the bilayer hydrocarbon region thickness of d(
HC) = 28.4 +/- 0.6 Angstrom, the bilayer thickness 47.4 Angstrom less
than or equal to d(L) I 48.1 Angstrom, the phospholipid molecule surfa
ce area 64.0 Angstrom(2) less than or equal to A(L) less than or equal
to 64.6 Angstrom(2) at the bilayer/water interface, the number of wat
er molecules 9.17 less than or equal to n(h) less than or equal to 9.5
7 penetrated into the polar region of the bilayer per one phospholipid
and the mean molecular volume 28 Angstrom(3) less than or equal to V-
w' less than or equal to 30 Angstrom(3) of penetrated water have been
obtained from the small-angle X-ray scattering repeat distance of the
liquid-crystalline L-alpha phase of egg yolk phosphatidylcholine hydra
ted by 13 < n < 20 water molecules per one lipid.