Vitamin E Has Reduced Affinity for a Polyunsaturated Phospholipid: An Umbrella Sampling Molecular Dynamics Simulations Study,The Journal of Physical Chemistry B

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Vitamin E Has Reduced Affinity for a Polyunsaturated Phospholipid: An Umbrella Sampling Molecular Dynamics Simulations Study
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2018-08-28 , DOI: 10.1021/acs.jpcb.8b05016
Xiaoling Leng ₁ , Fangqiang Zhu ₁ , Stephen R. Wassall ₁

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Vitamin E is an essential micronutrient. The primary function of this lipid-soluble antioxidant is to protect membrane phospholipids from oxidation. Whether vitamin E preferentially interacts with polyunsaturated phospholipids to optimize protection of the lipid species most vulnerable to oxidative attack has been an unanswered question for a long time. In this work, we compared the binding of α-tocopherol (αtoc), the form of vitamin E retained by the human body, in bilayers composed of polyunsaturated 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22:6PC) and, as a control, monounsaturated 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) by umbrella sampling molecular dynamics simulations. From the potential of mean force as a function depth within the bilayer, we find that the binding energy of αtoc is less in SDPC (ΔG_bind = 16.7 ± 0.3 kcal/mol) than that in SOPC (ΔG_bind = 18.3 ± 0.4 kcal/mol). The lower value in SDPC is ascribed to the high disorder of polyunsaturated fatty acids that produces a less tightly packed arrangement. Deformation of the bilayer is observed during desorption, indicating that phosphatidylcholine (PC)–PC and αtoc–PC interactions contribute to the binding energy. Our results do not support the proposal that vitamin E interacts more favorably with polyunsaturated phospholipids.

中文翻译：

维生素E降低了对多不饱和磷脂的亲和力：伞采样分子动力学模拟研究。

维生素E是必不可少的微量营养素。这种脂溶性抗氧化剂的主要功能是保护膜磷脂免于氧化。维生素E是否优先与多不饱和磷脂相互作用以优化对最易受到氧化攻击的脂质的保护，这一直是一个长期未解决的问题。在这项工作中，我们比较了α-生育酚（αtoc）（由人体保留的维生素E形式）在由多不饱和的1-硬脂酰基-2-十二碳六烯酰基磷脂酰胆碱（SDPC，18：0-22：6PC）组成的双层中的结合作为对照，通过伞式采样分子动力学模拟，获得单不饱和的1-硬脂酰基-2-油酰基磷脂酰胆碱（SOPC，18：0-18：1PC）。从平均力作为双层内函数深度的潜能，我们发现SDPC中αtoc的结合能较小（Δģ_绑定=比SOPC 16.7±0.3千卡/摩尔）（Δ ģ_绑定= 18.3±0.4千卡/摩尔）。SDPC中较低的值归因于多不饱和脂肪酸的高度混乱，从而导致排列不紧密的排列。在解吸过程中观察到双层变形，表明磷脂酰胆碱（PC）–PC和αtoc–PC相互作用有助于结合能。我们的结果不支持维生素E与多不饱和磷脂相互作用更有利的提议。

更新日期：2018-08-29

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