物理化学学报 >> 2011, Vol. 27 >> Issue (01): 213-227.doi: 10.3866/PKU.WHXB20110109

生物物理化学 上一篇    下一篇

α-生育酚在模型生物膜中的分子动力学模拟

秦姗姗, 尉志武   

  1. 清华大学化学系, 生命有机磷与化学生物系教育部重点实验室, 北京 100084
  • 收稿日期:2010-09-13 修回日期:2010-10-22 发布日期:2010-12-31
  • 通讯作者: 尉志武 E-mail:yuzhw@tsinghua.edu.cn
  • 基金资助:

    国家自然科学基金(20633080, 20973100)资助项目

Molecular Dynamics Simulations of α-Tocopherol in Model Biomembranes

QIN Shan-Shan, YU Zhi-Wu   

  1. Key Laboratory of Bioorganic Phosphorous Chemistry & Chemical Biology, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
  • Received:2010-09-13 Revised:2010-10-22 Published:2010-12-31
  • Contact: YU Zhi-Wu E-mail:yuzhw@tsinghua.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20633080, 20973100).

摘要: 用分子动力学方法模拟了280, 310和350 K下α-生育酚在二豆蔻酰磷脂酰胆碱、二豆蔻酰磷脂酰乙醇胺、二硬脂酰磷脂酰胆碱和二硬脂酰磷脂酰乙醇胺双层膜中的性质, 包括了空间位置、氢键、取向和动力学性质, 取得了如下的结论. 第一, 生育酚头部的羟基一般位于脂双层亲疏水界面的下方, 升高温度将促进羟基向膜双层的中心移动, 在350 K时观察到了在上下两个单层间的翻转. 第二, 生育酚主要与磷脂的酯基形成氢键, 几乎不与磷脂酰乙醇胺的氨基形成氢键; 比较生育酚与磷脂酰胆碱和乙醇胺形成的氢键后发现, 后者更稳定. 第三, 生育酚的头部在膜中取向多变, 与膜的法线夹角不固定, 尾部的构象也很复杂. 第四, 在温度较低时, 生育酚的侧向扩散系数与磷脂的相当, 但在350 K时其扩散速度明显加快; 在垂直方向生育酚的扩散速度很慢.

关键词: 维生素E, 磷脂, 取向, 翻转, 扩散, 氢键

Abstract: Molecular dynamics simulations of α-tocopherol in a number of saturated phospholipid bilayers were performed at 280, 310, and 350 K. The phospholipids contained either short acyl tails, i.e., dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine or long acyl tails, namely distearoylphosphatidylcholine and distearoylphosphatidylethanolamine. The preferential position, hydrogen bonding, orientation, and dynamic properties of α-tocopherol in the bilayers were examined in detail and several conclusions were made. First, the hydroxyl group of α-tocopherol generally remains beneath the interfacial region of the lipid bilayers and it shifts toward the bilayer mid-plane with an increase in temperature. At 350 K it flip-flops between the upper and lower leaflets in the four lipid bilayers. Second, α-tocopherol mainly forms hydrogen bonds with the carbonyl ester oxygen in the lipid head groups and hardly forms hydrogen bonds with the amino groups in the phosphatidylethanolamine (PE) bilayers. Hydrogen bonding with PEs is more stable than hydrogen bonding with phosphatidylcholines (PCs) at low temperatures. Third, α-tocopherol's head group has fluctuating tilt angles relative to the normal of the lipid bilayers and the tail has many different conformations. Fourth, the lateral diffusion rate of α-tocopherol is comparable to that of phospholipid molecules at low temperature and it diffuses much faster than lipids at 350 K. The diffusion rate in the direction perpendicular to the membrane surface is much slower than the lateral diffusion rate.

Key words: Vitamin E, Phospholipid, Orientation, Flip-flop, Diffusion, Hydrogen-bond

MSC2000: 

  • O641