Detailed structure and dynamics of bicelle phospholipids using selectively deuterated and perdeuterated labels.: 2H NMR and molecular mechanics study
Detailed structure and dynamics of bicelle phospholipids using selectively deuterated and perdeuterated labels.: 2H NMR and molecular mechanics study
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DOI：
10.1021/la034268q
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发表时间：
2003-12-09
期刊：
影响因子：
3.9
通讯作者：
Dufourc, EJ
中科院分区：
文献类型：
--
作者：
Aussenac, F;Laguerre, M;Dufourc, EJ
二肉豆蔻酰磷脂酰胆碱（DMPC）已被完全或选择性氘代的头基，甘油主链，和酰基链。固态氘和磷NMR应用于这种脂质，目的是全面描绘其结构和动力学时，嵌入在bicelles或脂质体。分子力学计算也完成了完全水合DMPC双层。主要结果有四个方面。(a)在整个膜厚度的局部脂质动力学可以准确地描述：甘油骨干显示出一个非常有限的motional自由，可以被认为是一个半刚性的“rotula”分离两个非常流体区，磷酸胆碱头基面临的水介质和酰基链构成的油性双层内部。(b)利用核磁共振、分子力学和X射线衍射等方法，计算了DMPC甘油主链运动主轴的位置及其分子序参量S-mol。尽管后者缺乏氢原子的准确结构数据，但总的趋势是甘油g2-g3碳-碳键的取向相对于双层法线约为28度，并且对于嵌入双胞中的78%DMPC，S 01值为0.55。(c)在晶体中较早报道的两种DMPC构象A和B（Pearson，H.;帕舍岛Nature 1979，181，499-501）也存在于完全水合DMPC的所有分子动力学运行中。(d)有一个显着的DMPC相变温度降低后，增加选择性氘含量的脂质结构。有趣的是，五个甘油骨架位置的标记诱导与全链氘化（54个位置）相同的温度降低。
Dimyristoylphophatidylcholine (DMPC) has been entirely or selectively deuterated on the headgroup, glycerol backbone, and acyl chains. Solid-state deuterium and phosphorus NMR was applied to this lipid with the aim to comprehensively depict its structure and dynamics when embedded in bicelles or in liposomes. Molecular mechanics calculations were also accomplished on fully hydrated DMPC bilayers. The main results are fourfold. (a) The local lipid dynamics across the entire membrane thickness could be accurately described: the glycerol backbone shows a very restricted motional freedom and can be considered as a semirigid "rotula" separating two very fluid zones, the phosphocholine headgroup facing the water medium and the acyl chains constituting the oily bilayer interior. (b) The location of the principal axis of motion of the glycerol backbone of DMPC and its molecular order parameter, S-mol, were calculated by making use of NMR, molecular mechanics, and X-ray data reported in earlier studies. Although the later lacks in accurate structural data for hydrogen atoms, there is nonetheless a general trend for an orientation of the glycerol g2-g3 carbon-carbon bond at about 28degrees with respect to the bilayer normal and for a S 01 value of 0.55 for 78% DMPC embedded in bicelles. (c) The two DMPC conformers A and B that were earlier reported in the crystal (Pearson, H.; Parsher, I. Nature 1979, 181, 499-501) also exist in all molecular dynamics runs of fully hydrated DMPC. (d) There is a marked decrease of the DMPC phase transition temperature upon increasing selective deuterium content in the lipid structure. Interestingly, labeling of the five glycerol backbone positions induces the same temperature decrease as a full chain deuteration (54 positions).