title: Transverse distribution of alpha-tocopherol in bilayer membranes studied by fluorescence quenching.
abstract: The fluorescence properties of alpha-tocopherol in a range of solvents and in micelles and membrane vesicles have been measured. In solvents the fluorescence decay was fitted by a single exponential. In bilayer membranes of dipalmitoylphosphatidylcholine or egg phosphatidylcholine the fluorescence decay was more accurately fitted as a double exponential. This may indicate that alpha-tocopherol occupies two or more sites in such membranes. Depth-dependent quenching of alpha-tocopherol fluorescence by acrylamide and some doxyl stearates has also been studied. The results confirm that in gel-phase lipid the chromanol group has a transverse distribution close to the head-group region of the lipid. In fluid phase lipid in the presence of buffer the results indicate there is more penetration of the chromanol group into the bilayer.
authors.affiliation: Department of Biological Sciences, University of Salford, U.K.
authors.forename: R H
authors.initials: RH
authors.lastname: Bisby
authors.forename: S
authors.initials: S
authors.lastname: Ahmed
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine; D020106:Acrylamide; D000178:Acrylamides; D003497:Cyclic N-Oxides; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000032:analysis*; D008081:Liposomes / Q000032:analysis; D008823:Micelles; D009994:Osmolar Concentration; D010713:Phosphatidylcholines / Q000032:analysis; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013113:Spin Labels; D014810:Vitamin E / Q000032:analysis*
chemical_list: D000178:Acrylamides; D003497:Cyclic N-Oxides; D008051:Lipid Bilayers; D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D012997:Solvents; D013113:Spin Labels; D014810:Vitamin E; D020106:Acrylamide; D015060:1,2-Dipalmitoylphosphatidylcholine; C005072:5-doxylstearic acid; C060365:9-doxylstearate; C032363:16-nitroxystearic acid