Effect of unsaturated phosphatidylethanolamine on the chain order profile of bilayers at the onset of the hexagonal phase transition. A 2H NMR study.
Effect of unsaturated phosphatidylethanolamine on the chain order profile of bilayers at the onset of the hexagonal phase transition. A 2H NMR study.
复制标题
不饱和磷脂酰乙醇胺对六方相变开始时双层链序分布的影响。
DOI：
10.1021/bi00503a010
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Hui,SW
中科院分区：
文献类型：
--
作者：
Fenske,DB;Jarrell,HC;Guo,Y;Hui,SW
加拿大国家研究委员会生物科学部，渥太华，安大略，加拿大 K1A 0R6，以及膜生物物理学实验室，罗斯威尔公园纪念研究所，布法罗，纽约 14263 收稿日期：1990 年 3 月 19 日；修订稿于 8 月 22 日收到，¡ 990 摘要：通过 2 H NMR 研究了全氘代二肉豆蔻酰磷脂酰胆碱 (DMPC-í/54) 与二油酰磷脂酰乙醇胺 (DOPE) 混合物中亚甲基沿酰基链的四极分裂谱。对双层状态的脂质混合物获得的四极分裂作为温度和 PE:PC 比率的函数进行测量，并用于获得给定链位置 pB 处的近似稀疏概率。 Cl 3、Cl2 和 Cl 1 的 pB 相对于平台区域的比率 (R) 用于表征增加 PE 对 PC 链的稀疏含量的影响。在所研究的所有温度下（包括双层到六角形相变区域），对于每个比率R（例如，J？ci3/p），DMPC链的相对稀疏含量在25-85%PE的范围内是相似的。 DOPE 简单来说被视为具有“圆锥形”形状；如果这种几何形状适用于分子的酰基链区域，随着 PE 含量的增加，预计双层中心会有更大的侧向压力，导致 PC 的亚甲基基团相对于平台的高斯含量降低。未能观察到预测的侧压增加会对锥形分子模型产生影响。 PE 的整体“锥形”形状是由于头基尺寸相对于酰基链较小而产生的；然而，酰基链区域本身并不是严格的锥形，最好用柔性的“气球”来表示。这些结果得到了小角 X 射线衍射的支持，小角 X 射线衍射显示，随着 PE 含量的增加，每个分子的面积呈减小趋势。
Division of Biological Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6, and Membrane Biophysics Laboratory, Roswell ParkMemorial Institute, Buffalo, New York 14263 Received March 19, 1990; Revised Manuscript Received August 22,¡ 990 abstract: The quadrupolar splitting profiles of methylene groups along the acyl chains of perdeuteriated dimyristoylphosphatidylcholine (DMPC-í/54) in mixtures with dioleoylphosphatidylethanolamine (DOPE) were studied by 2H NMR. The quadrupolar splittings, obtained for lipid mixtures in the bilayer state, were measured as functions of temperature and PE: PC ratio and were used to obtain the approximate gauche probabilities at a given chain position, pB. Ratios (R) of pB for Cl 3, Cl2, and Cl 1 relative to that of the plateau region were used to characterize the effect of increasing PE on the gauche content of PC chains. At all temperatures studied (including the bilayer to hexagonal phase transition region), for each ratio R (eg, J? ci3/p), the relative gauchecontent of the DMPC chains was similar over the range of 25-85% PE. DOPE is viewed in simple terms as having a “conical” shape; if this geometry applies to the acyl chain region of the molecule, a greater lateral pressure would be expected toward the center of the bilayer as the PE content is increased, resulting in a decreased gauche content, relative to theplateau, of those methylene groups of PC. The failure to observe thepredicted increase in lateral pressure has ramifications for the cone-shape molecular model. The overall “cone shape” of PE is seen to arise from the smaller size of the head-group relative to the acyl chains; however, the acyl chain region itself is not rigidly cone-shaped and is better represented by a flexible “balloon”. These results were supported by small-angle X-ray diffraction, which showed a decreasing trend in the area per molecule with increasingPE content.