title: Effect of orientational order on the decay of the fluorescence anisotropy in membrane suspensions. Experimental verification on unilamellar vesicles and lipid/alpha-lactalbumin complexes.
abstract: Various models for the analysis of time-dependent fluorescence anisotropy measurements were evaluated. The discussion was based on the analysis of pulsed experiments with 1,6-diphenyl-1,3,5-hexatriene embedded in small unilamellar vesicles of dimyristoylphosphatidylcholine or dipalmitoylphosphatidylcholine and in dimyristoylphosphatidylcholine/alpha-lactalbumin complexes. It was shown that a recently proposed model (Van der Meer, W., H. Pottel, W. Herreman, M. Ameloot, H. Hendrickx, H. Schröder, 1984, Biophys. J., 46:515-523) described the data better than did the earlier suggested cone model (Kinosita K., Jr., S. Kawato, and A. Ikegami, 1977, Biophys. J., 20:289-305). This permitted the use of the new model for the estimation of the second- and fourth-rank order parameters on nonoriented systems. The results indicated that a fraction of the probes was oriented perpendicularly to the preferred direction of the lipids. An increase of the rotational correlation times of the fluorescent probe and a higher order of its environment were detected after the interaction of alpha-lactalbumin with the dimyristoylphosphatidylcholine vesicles at acidic pH at 24.2 degrees C.
mesh_terms: D000818:Animals; D002417:Cattle; D004134:Dimyristoylphosphatidylcholine; D004161:Diphenylhexatriene; D005260:Female; D005454:Fluorescence Polarization; D007768:Lactalbumin; D008081:Liposomes; D008433:Mathematics; D008892:Milk; D008954:Models, Biological; D011663:Pulmonary Surfactants
chemical_list: D008081:Liposomes; D011663:Pulmonary Surfactants; D004161:Diphenylhexatriene; D007768:Lactalbumin; D004134:Dimyristoylphosphatidylcholine