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The effect of acyl chain unsaturation on phospholipid bilayer.

机译：酰基链不饱和度对磷脂双层的影响。

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摘要

Each biological cell is surrounded by a membrane that consists of many different kinds of lipids. The lipids are mainly composed of phospholipids, which form a fluid bilayer that serves as the platform for the function of membrane bound proteins regulating cellular activity. In the research described in this thesis we employed solid state 2H NMR, complemented by DSC (differential scanning calorimetry) and MD (molecular dynamics) simulations, to study the effect of PUFA (polyunsaturated fatty acids) and TFA ( trans fatty acids) on molecular organization in protein-free model membranes of controlled composition. These two classes of unsaturated fatty acid incorporate into membrane lipids and have, respectively, a beneficial and harmful impact on health. The aim is to gain insight into the molecular origin of this behavior. DHA (docosahexaenoic acid), which with 6 "natural" cis double bonds is the most highly unsaturated PUFA found in fish oils, and EA (elaidic acid), which with only a single "unnatural" trans double bond is the simplest manmade TFA often found in commercially produced food, were the focus.;2H NMR spectra for [2H31]-N-palmitoylsphingomyelin ([2H31]16:0SM) in SM/16:0-22:6PE (1-palmitoyl-2-docosahexaenoylphosphatidylethanolamine)/cholesterol (1:1:1 mol) mixed membranes were recorded. This system served as our PUFA-containing model. The spectra are consistent with lateral separation into nano-sized ( 20 nm) domains that are SM-rich/cholesterol-rich (raft), characterized by higher chain order, and DHA-rich/cholesterol-poor (non-raft), characterized by lower chain order. The aversion cholesterol has for DHA, as opposed to the affinity cholesterol has for predominantly saturated SM, excludes the sterol from DHA-containing PE-rich domains and DHA from SM-rich/cholesterol-rich domains. It is the formation of highly disordered membrane domains that we hypothesize is responsible, in part, for the diverse health benefits associated with dietary consumption of DHA.;2H NMR spectra for 1-elaidoyl-2-[2H 35]stearoylphosphatidylcholine (t18:1-[2H 35]18:0PC) and 1-oleoyl-2-[2H35]stearoylphosphatidylcholine (c18:1-[2H35]18:0PC) were recorded to compare membranes with respect to a trans vs. cis ("natural") double bond. The spectra indicate that while a trans double bond produces a smaller deviation from linear conformation than a cis double bond, membrane order is decreased by a comparable amount because the energy barrier to rotation about the C-C single bonds either side of a trans or cis double bond is reduced. Although EA adopts a conformation somewhat resembling a saturated fatty acid, the TFA is almost as disordered as its cis counterpart oleic acid (OA). We speculate that EA could be mistaken for a saturated fatty acid and infiltrate lipid rafts to disrupt the high order therein that is necessary for the function of signaling proteins.
机译：每个生物细胞被膜包裹，该膜由许多不同种类的脂质组成。脂质主要由磷脂组成，磷脂形成流体双层，其充当膜结合蛋白调节细胞活性的功能的平台。在本文描述的研究中，我们采用固态2 H NMR，并辅以DSC（差示扫描量热法）和MD（分子动力学）模拟，以研究PUFA（多不饱和脂肪酸）和TFA（反式脂肪酸）对分子的影响组织在无蛋白的模型膜中，组成受控。这两类不饱和脂肪酸结合到膜脂中，分别对健康产生有益和有害的影响。目的是深入了解这种行为的分子起源。具有6个“天然”顺式双键的DHA（二十二碳六烯酸）是鱼油中发现的高度不饱和的PUFA，而只有一个“非天然”反式双键的EA（二十二碳六烯酸）通常是最简单的人造TFA [2H31] -N-棕榈酰基鞘磷脂（[2H31] 16：0SM）在SM / 16：0-22：6PE（1-棕榈酰基-2-十二碳六烯酰基磷脂酰乙醇胺）/中的2H NMR光谱/记录胆固醇（1：1：1 mol）混合膜。该系统充当了我们包含PUFA的模型。光谱与横向分离成纳米级（<20 nm）域一致，纳米域富含SM /富含胆固醇（筏），其特征在于更高的链序，而DHA富含/胆固醇贫乏（非筏），特点是较低的连锁顺序。与胆固醇对主要饱和的SM的亲和力相反，厌恶性胆固醇对DHA的抵抗力除外，它从富含DHA的PE丰富域中去除了固醇，而从富含SM的/胆固醇丰富的域中排除了DHA。我们假设这是高度无序的膜结构域的形成，部分原因是与饮食中摄入DHA有关的多种健康益处。； 1-弹性基-2- [2H 35]硬脂酰磷脂酰胆碱（t18：1）的2 H NMR光谱记录-[[2H 35] 18：0PC）和1-油酰基-2- [2H35]硬脂酰磷脂酰胆碱（c18：1- [2H35] 18：0PC），以比较反式与顺式（“天然”）的膜双键。光谱表明，虽然反式双键与顺式双键相比，其线性构象的偏差较小，但由于反式或顺式双键任一侧绕CC单键旋转的能量垒，膜序降低了相当数量。降低了。尽管EA采用的构象有点类似于饱和脂肪酸，但TFA几乎与其顺式对应的油酸（OA）一样无序。我们推测，EA可能被误认为是饱和脂肪酸，并渗入脂质筏以破坏其中的高级信号，这对于信号蛋白的功能是必需的。

著录项

  • 作者

    Soni, Smita Pravin.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Biophysics General.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 177 p.
  • 总页数 177
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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