Vitamin E does not Disturb Polyunsaturated Fatty Acid Lipid Domains

Published

November 1, 2022

Author(s)

Mitchell DiPasquale, Michael H. Nguyen, Stuart R. Castillo, Isabelle J. Dib, Elizabeth Kelley, Drew Marquardt

Abstract

The antioxidant function of vitamin E in biomembranes remains a prominent topic of discussion. As its limitations as an antioxidant persist and novel functions are discovered, our understanding of the role of vitamin E becomes increasingly enigmatic. As a lipophilic molecule, vitamin E has been shown to influence the properties of its host membrane, and a wealth of research has connected vitamin E to polyunsaturated fatty acid (PUFA) lipids. Here, we use contrast-matched small angle neutron scattering and differential scanning calorimetry to integrate these fields by examining the influence of vitamin E on lipid domain stability in PUFA-based lipid mixtures. The influence of α-tocopherol, γ-tocopherol, and α-tocopherylquinone on the lateral organization of a 1:1 lipid mixture of saturated distearoylphosphatidylcholine (DSPC) and polyunsaturated palmitoyl-linoleoylphosphatidylcholine (PLiPC) with cholesterol provides a complement to our growing understanding of the influence of tocopherol on lipid phases. Characterization of domain melting suggests a slight depression in the transition temperature and a decrease in transition cooperativity, which are consistent with previous calorimetric studies. Tocopherol concentrations that are an order of magnitude higher than anticipated physiological concentrations (2 mole percent) do not significantly perturb lipid domains; however, addition of 10 mole percent is able to destabilize domains and promote lipid mixing. This observation is qualitatively consistent with our previous study based in a composition with macroscopic domains of high line tension. In contrast to this behaviour, increasing concentrations of the oxidized product of α-tocopherol, α-tocopherylquinone, induces a proportional increase in domain stabilization. We speculate how the contrasting effect of the oxidized product may supplement the antioxidant response of vitamin E.

Citation

Biochemistry

Volume

61

Issue

21

Pub Type

Journals

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DOI Link

Keywords

vitamin E, tocopherol, polyunsaturated fatty acid (PUFA), domains, phase separation, small angle neutron scattering

Citation

DiPasquale, M. , Nguyen, M. , Castillo, S. , Dib, I. , Kelley, E. and Marquardt, D. (2022), Vitamin E does not Disturb Polyunsaturated Fatty Acid Lipid Domains, Biochemistry, [online], https://dx.doi.org/10.1021/acs.biochem.2c00405 (Accessed July 7, 2024)