properties of lipid bilayer systems are compared for symmetric chain sphingomyelin
(N-palmitoylsphingomyelin) and asymmetric chain sphingomyelin (N-lignoceroylsphingomyelin).
These sphingomyelins were semisynthesized by a deacylation- reacylation process
with a natural sphingomyelin used as a starting material. The number of differently
bound water molecules was estimated by a deconvolution analysis of the ice-melting
curves obtained by a differential scanning calorimetry (DSC) and was used
to construct a water distribution diagram for these water molecules. Similarly
to a natural sphingomyelin used for comparison, the asymmetric chain sphingomyelin
was found to form small size vesicles having an internal cavity and incorporate
15 water molecules per molecule of lipid into its cavity, in contrast with
5 H2O/lipid for freezable interlamellar water observed
for large size multilamellar vesicles formed by the symmetric chain sphingomyelin.