Measurement of the lateral diffusion coefficients of ubiquinones in lipid vesicles by fluorescence quenching of 12-(9-anthroyl)stearate

The lateral diffusion coefficients of some ubiquinone homologues have been measured in phospholipid vesicles exploiting the fluorescence quenching of the probe 12-(9-anthroyl)stearate by the quinones. Diffusion coefficients higher than 10(-6) cm2 X s-1 have been found at 25 degrees C, compatible with the localization of the ubiquinones in the low-viscosity midplane region of the bilayer.