Since its discovery over 90 years ago, the biological significance of vitamin E (tocopherol) has been surrounded by controversy. Putatively referenced as a potent fat-soluble antioxidant, α-tocopherol has also been linked to a diverse range of cellular processes including signalling, apoptosis, protein activity, and gene regulation, along with disease states such as infertility and neuromuscular dysfunction, though molecular mechanisms for the latter remain elusive. Considering the lack of conclusive investigations, the absence of a clear antioxidant health benefit from supplementation, and its significantly low physiological concentrations, skepticism builds regarding the true biological function of vitamin E. Since it localizes in the membrane, our research looks to address the physical perturbations of the membrane induced by the presence of tocopherol.<br/>Previous experiments on model membranes have revealed that α-tocopherol favours localization in less ordered lipid environments, specifically those provided by oxygen-sensitive polyunsaturated fatty acids – an association that is almost innate for an effective antioxidant. Moreover, through neutron diffraction and small angle X-ray scattering, α-tocopherol has been found to position itself precisely in the membrane to host a dual-faceted antioxidant mechanism, while not significantly altering the structure of the membrane.<br/>Current investigations employ small angle neutron scattering with contrast matching techniques to study the effect of various tocopherols on domain formation. Organization of lipids into domains is thought to be an integral aspect of membrane functionalization as proposed by the lipid raft hypothesis. Using model large unilamellar lipid vesicles capable of phase-separation, the effect of tocopherol on domain stability is studied in both monounsaturated and polyunsaturated systems. Preliminary results indicate that increasing tocopherol concentration correlates to both the reduction and destabilization of ordered domains. Alterations in the membranes physical properties endorses the significance of vitamin E in membrane systems by suggesting a potential biological role beyond that of solely an antioxidant.

Investigating the physical presence of vitamin E in lipid membranes

2019 Spring National Meeting

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