Thermotropic interaction of vitamin E with dimyristoyl and dipalmitoyl phosphatidylcholine liposomes.

The effect of vitamin E on the thermal behavior of two saturated phosphatidylcholines was investigated by differential scanning calorimetry. For dimyristoyl and dipalmitoyl phosphatidylcholines, the addition of vitamin E at concentrations of 1, 5 and 10 mol% vitamin E, resulted in a lowering of the phase transition temperature and a broadening of the temperature range of the phase transition indicating an increase in the fluidity of the phospholipids. Taken together with other physical studies on the effect of vitamin E on (unsaturated) phospholipids, these results indicate that vitamin E could influence the physical properties of membrane phospholipids in addition to its known antioxidant role. The likelihood of this interaction would be enhanced if vitamin E was not randomly distributed in biological membranes but rather was located in domains where its local concentration, relative to phospholipids, was elevated.