Martinez-Seara Hector, Róg Tomasz, Karttunen Mikko, Reigada Ramon, Vattulainen Ilpo
Department of Physical Chemistry, Universitat de Barcelona, Avda. Diagonal 647, 08028 Barcelona, Spain.
J Chem Phys. 2008 Sep 14;129(10):105103. doi: 10.1063/1.2976443.
We have employed atomistic molecular dynamics simulations to investigate the effect of double-bond parametrization on lipid membrane properties. As models, we use one-component membranes composed of glycerol-based phosphatidylcholines (PCs) with monounsaturated acyl chains, and we complement these studies by additional PC/cholesterol simulations. We compare differences between double-bond parametrizations by varying the position of the double bond systematically along the lipid hydrocarbon chains. The results give rise for concern: They indicate that the double-bond description may change not only the quantitative but also the qualitative nature of membrane behavior. In particular, we find that the double-bond description which accounts for skew states in the vicinity of a double bond predicts a maximum in membrane disorder, when the double bond resides at the middle of an acyl chain, in agreement with experiments. The more commonly used description which does not accommodate skew states, however, predicts membrane disorder to decrease monotonically as the double bond is shifted from the glycerol backbone to the end of an acyl chain. The results highlight the importance of properly describing double bonds especially in many-component membranes, where the interplay of different molecule types is difficult to predict on intuitive grounds.
我们采用了原子分子动力学模拟来研究双键参数化对脂质膜性质的影响。作为模型，我们使用由具有单不饱和酰基链的甘油基磷脂酰胆碱（PC）组成的单组分膜，并通过额外的PC/胆固醇模拟来补充这些研究。我们通过沿着脂质烃链系统地改变双键的位置来比较双键参数化之间的差异。结果令人担忧：它们表明双键描述不仅可能改变膜行为的定量性质，还可能改变其定性性质。特别是，我们发现考虑双键附近扭曲状态的双键描述预测，当双键位于酰基链中间时，膜无序度会达到最大值，这与实验结果一致。然而，更常用的不考虑扭曲状态的描述预测，随着双键从甘油主链向酰基链末端移动，膜无序度会单调降低。这些结果突出了正确描述双键的重要性，特别是在多组分膜中，不同分子类型之间的相互作用很难凭直觉预测。
