Fluorescence lifetimes study of alpha-tocopherol and biological prenylquinols in organic solvents and model membranes.
We have found that for biological prenyllipids, such as plastoquinol-9, alpha-tocopherol quinol, and alpha-tocopherol, the shortest fluorescence lifetimes were found in aprotic solvents (hexane, ethyl acetate) whereas the longest lifetimes were those of ubiquinonol-10 in these solvents. For all the investigated prenyllipids, fluorescence lifetime in alcohols increased along with an increase in solvent viscosity. In a concentrated hexane solution, the lifetimes of prenylquinols considerably decreased. This contrasts with methanol solutions, which is probably due to the self-association of these compounds in aprotic solvents. We have also found a correlation of the Stokes shift of prenyllipids fluorescence with the orientation polarizability of the solvents. Based on data obtained in organic solvents, measurements of the fluorescence lifetimes of prenyllipids in liposomes allowed an estimation of the relative distance of their fluorescent rings from the liposome membrane surface, and was found to be the shortest for alpha-tocopherol quinol in egg yolk phosphatidylcholine liposomes, and increased in the following order: alpha-tocopherol in dipalmitoyl phosphatidylcholine liposomes < alpha-tocopherol < plastoquinol-9 < ubiquinol-10 in egg-yolk phosphatidylcholine liposomes.
Kruk
Jerzy
J
Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland. jkruk@mol.uj.edu.pl
Myśliwa-Kurdziel
Beata
B
Jemioła-Rzeminiska
Małgorzata
M
Strzałka
Kazimierz
K
D002151:Calorimetry; D005453:Fluorescence; D006873:Hydroquinones / Q000528:radiation effects*; D008081:Liposomes; D008567:Membranes, Artificial; D012997:Solvents; D024502:alpha-Tocopherol / Q000528:radiation effects*
D006873:Hydroquinones; D008081:Liposomes; D008567:Membranes, Artificial; D012997:Solvents; D024502:alpha-Tocopherol