Partition, orientation and mobility of ubiquinones in a lipid bilayer
Partition, orientation and mobility of ubiquinones in a lipid bilayer
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DOI：
10.1016/j.bbabio.2015.08.001
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发表时间：
2015-12-01
影响因子：
4.3
通讯作者：
Arantes, Guilherme Menegon
中科院分区：
文献类型：
--
作者：
Galassi, Vanesa Viviana;Arantes, Guilherme Menegon
泛醌是生物电子传递过程中普遍存在的移动的电荷载体。它的氧化还原性质和生物学功能取决于其在生物膜上的分子分配和侧向扩散。然而，泛醌定位和动态内脂双层长期争论，仍然不确定。在这里，我们提出了几个泛醌同系物与可变的类异戊二烯的尾巴长度复杂的磷脂酰胆碱双层的分子动力学模拟。最初，一个新的力场参数化泛醌是来自高层次的量子化学数据和比较。泛醌在脂质双层插入的自由能分布与新的力场。的配置文件允许泛醌在膜中的平衡位置的确定，以及通过与实验分配系数直接比较的模拟模型的验证。结构特性和相互作用的详细分析表明，泛醌极性头基是本地化的水双层界面在相同的深度的脂质甘油基团和取向的膜平面垂直。泛醌头部基团的定位和取向不改变显着增加类异戊二烯单元的数量时。类异戊二烯尾部被延长并与脂质酰基链包装在一起。对于具有长尾的泛醌，末端类异戊二烯单元具有高柔性。计算出的泛醌扩散系数与磷脂酰胆碱脂质的扩散系数相似。这些结果可能有进一步的影响泛醌运输和结合呼吸和光合作用蛋白复合物的机制。(C)2015 Elsevier B.V.版权所有。
Ubiquinone is the universal mobile charge carrier involved in biological electron transfer processes. Its redox properties and biological function depend on the molecular partition and lateral diffusion over biological membranes. However, ubiquinone localization and dynamics within lipid bilayers are long debated and still uncertain. Here we present molecular dynamics simulations of several ubiquinone homologs with variable isoprenoid tail lengths complexed to phosphatidylcholine bilayers. Initially, a new force-field parametrization for ubiquinone is derived from and compared to high level quantum chemical data. Free energy profiles for ubiquinone insertion in the lipid bilayer are obtained with the new force-field. The profiles allow for the determination of the equilibrium location of ubiquinone in the membrane as well as for the validation of the simulation model by direct comparison with experimental partition coefficients. A detailed analysis of structural properties and interactions shows that the ubiquinone polar head group is localized at the water bilayer interface at the same depth of the lipid glycerol groups and oriented normal to the membrane plane. Both the localization and orientation of ubiquinone head groups do not change significantly when increasing the number of isoprenoid units. The isoprenoid tail is extended and packed with the lipid acyl chains. For ubiquinones with long tails, the terminal isoprenoid units have high flexibility. Calculated ubiquinone diffusion coefficients are similar to that found for the phosphatidylcholine lipid. These results may have further implications for the mechanisms of ubiquinone transport and binding to respiratory and photosynthetic protein complexes. (C) 2015 Elsevier B.V. All rights reserved.