A spin label ESR and saturation transfer ESR study of alpha-tocopherol containing model membranes

An investigation into the effect of alpha-tocopherol on phospholipid model membranes has been carried out by electron spin resonance (ESR) and saturation transfer ESR. The use of stearic acid and of perdeutero -di-t-butyl nitroxide spin probes has allowed us to monitor, in particular, the effect of alpha-tocopherol on both the phospholipid chain order and the phospholipid chain mobility. The results obtained are mainly consistent with a differing action of alpha-tocopherol in the gel and in the liquid crystalline phases: in the former it induces a decrease of order and an increase in fluidity; while in the latter phase an indication of a slight increase in ordering and a clear decrease in fluidity are registered.