Interactions Of Vitamin E With Free Radicals And Membranes

-Tocopherol performs an antioxidant role in biological membranes by acting as a one-electron reductant. In micellar solutions it has been observed by pulse radiolysis that the micellar charge has a pronounced effect on the rate constant for repair of organic free radicals by -tocopherol. The interactions between -tocopherol and model bilayer lipid membranes have been studied by fluorescence spectroscopy. Quencing of -tocopherol fluorescence by acrylamide and some n-doxyl stearates shows the transverse distribution of -tocopherol in membranes to be affected by the physical state of the membrane lipids and by the salt concentration in the aqueous phase. Time-resolved fluorescence depolarization measurements, with a diphenylhexatriene-phospholipid conjugate as probe. demonstrate an increase in the bilayer order parameter on incorporation of -tocopherol into a membrane