双层大小和数量在完全和低水合下多层双层DOPC模拟中的影响,Langmuir

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双层大小和数量在完全和低水合下多层双层DOPC模拟中的影响
Langmuir ( IF 3.7 ) Pub Date : 2019-01-11 00:00:00 , DOI: 10.1021/acs.langmuir.8b03212
Sławomir S. Stachura ₁ , Chris J. Malajczuk ₁ , Egidijus Kuprusevicius ₁ , Ricardo L. Mancera ₁

Affiliation

通常在多层系统上使用散射测量来进行完全和低水合条件下模型细胞膜的生物物理研究。旨在复制那些实验条件的脂质双层的分子模拟通常是使用具有不同水量的单个双层进行的。由于周期性的边界条件，这些模拟条件可能会导致尺寸效应和自交互作用引起的伪影。在1,2-二油酰基-sn的分子动力学模拟中，我们使用脂质的Lipid14力场测试了双层的大小和数量对膜性能的影响-甘油3-磷酸胆碱双层在完全水合（每个脂质中有44个水分子），低水合（每个脂质中有18个水分子）和脱水（每个脂质中有9个水分子）时形成双层。为了进行比较，还对滑移力场进行了许多其他模拟。我们已经发现，对于所有水合状态，每个脂质的平均面积（APL），厚度，质量密度分布和酰基尾阶参数对双层的大小和数量均不敏感。Lipid14力场还可以成功地再现实验观察到的脱水后APL的降低以及相应的双层厚度的增加，反映出随着系统变得更加凝胶状，顺序的增加。此外，水化水平的降低与在两个力场上偏离正常横向扩散而趋向于更次扩散态的趋势有关。总之，至少对于Lipid14力场，使用具有128个磷脂分子的单分子双层可以在水合程度不同的情况下充分体现多层体系。

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Influence of Bilayer Size and Number in Multi-Bilayer DOPC Simulations at Full and Low Hydration

Biophysical studies of model cell membranes at full and low hydration are usually carried out using scattering measurements on multi-bilayer systems. Molecular simulations of lipid bilayers aimed at reproducing those experimental conditions are usually conducted using single bilayers with different amounts of water. These simulation conditions may lead to artifacts arising from size effects and self-interactions because of periodic boundary conditions. We have tested the influence of the size and number of bilayers on membrane properties using the Lipid14 force field for lipids in molecular dynamics simulations of 1,2-dioleoyl-sn-glycero-3-phosphocholine bilayers at full hydration (44 water molecules per lipid), low hydration (18 water molecules per lipid), and dehydration (9 water molecules per lipid). A number of additional simulations were conducted with the Slipids force field for comparison. We have found that the average area per lipid (APL), thickness, mass density profiles, and acyl tail order parameters are insensitive to the size and the number of bilayers for all hydration states. The Lipid14 force field can also successfully reproduce the experimentally observed decrease in APL and corresponding increase in bilayer thickness upon dehydration, reflecting the increase in ordering as the system becomes more gel-like. Additionally, decreasing hydration levels were associated with a trend away from normal lateral diffusion and toward more subdiffusive regimes across both force fields. In summary, at least for the Lipid14 force field, the use of a single bilayer with 128 phospholipid molecules provides an adequate representation of multi-bilayer systems at varying levels of hydration.

更新日期：2019-01-11

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