title: Perturbations of membrane structure by optical probes: II. Differential scanning calorimetry of dipalmitoyllecithin and its analogs interacting with Merocyanine 540.
abstract: Differential scanning calorimetry of multilamellar liposomes, interacting with the optical probe Merocyanine 540, yields quantitative information about perturbances of the bilayer structure induced by this dye. At low dye: lipid ratios, the dye perturbs primarily its own microenvironment, which is laterally separated from the unmodified lipid domain and exhibits modified thermotropic properties. A further increase in the dye concentration results in a perturbance of the whole lipid bilayer. The degree of perturbance is sensitive to structural modifications in the head-group region of the lipids. It is concluded that Merocyanine 540 reports in every case, even at infinite dilution, on localized events originating from a perturbed microenvironment.
mesh_terms: D001583:Benzoxazoles; D002152:Calorimetry, Differential Scanning; D008081:Liposomes; D008968:Molecular Conformation; D011663:Pulmonary Surfactants; D011744:Pyrimidinones; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D001583:Benzoxazoles; D008081:Liposomes; D011663:Pulmonary Surfactants; D011744:Pyrimidinones; C003954:merocyanine dye