title: Polar head molecular packing of dipalmitoylglycerophosphocholine in the gel state: a fluorescence investigation.
abstract: Binding of the fluorescent probe 8-anilino-1-naphthalenesulfonate to lecithin monolayers was shown to be dependent on the molecular packing of the lipids. No binding was observed in the gel state. The binding site appeared to be structurally unaffected during the compression of the monolayer, and it was concluded that the site was an assembly of "fluid" lipids. Four lipids are in close contact with the probe, and they are surrounded by 8-10 "fluidized" others. From these observations, the dissociation constant appeared as a good indicator of molecular packing at the polar head level in other lipid assemblies. In the gel state, macrovesicles and multilayers are a tight homogeneous assembly; at the same temperature, microvesicles display defects, in a highly fluid state, which are embedded in a rigid matrix where no binding occurs. Ten percent of the outer layer are in this "nongel" organization.
mesh_terms: D000817:Anilino Naphthalenesulfonates; D004134:Dimyristoylphosphatidylcholine; D005456:Fluorescent Dyes; D005782:Gels; D008081:Liposomes; D008954:Models, Biological; D008968:Molecular Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D005782:Gels; D008081:Liposomes; C027132:1-anilino-8-naphthalenesulfonate; D004134:Dimyristoylphosphatidylcholine