Valentine Mason L, Waterland Maya K, Fathizadeh Arman, Elber Ron, Baiz Carlos R
Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-1224, United States.
Oden Institute for Computational Science and Engineering, Austin, Texas 78712, United States.
J Phys Chem B. 2021 Feb 11;125(5):1343-1350. doi: 10.1021/acs.jpcb.0c08755. Epub 2021 Jan 28.
Phospholipid membranes support essential biochemical processes, yet remain difficult to characterize due to their compositional and structural heterogeneity. The two most common phospholipid headgroup structures in biological membranes are phosphatidylcholine (PC) and phosphatidylethanolamine (PE), but interactions between PC and PE lipids remain underexplored. In this study, we apply ultrafast two-dimensional infrared (2D IR) spectroscopy to quantify the headgroup effects on interfacial dynamics in PC/PE lipid mixtures. Experiments are interpreted through molecular dynamics simulations using the molecular dynamics with alchemical step (MDAS) algorithm for enhanced sampling. Experimental results indicate that the PE content decreases H-bond formation at the ester carbonyl positions near the lipid membrane's hydrophobic core as a result of increased packing density. The observed dehydration is linked to faster molecular dynamics within the interfacial region.
磷脂膜支持着重要的生化过程，但由于其组成和结构的异质性，仍然难以表征。生物膜中两种最常见的磷脂头部基团结构是磷脂酰胆碱（PC）和磷脂酰乙醇胺（PE），但PC和PE脂质之间的相互作用仍未得到充分研究。在本研究中，我们应用超快二维红外（2D IR）光谱来量化头部基团对PC/PE脂质混合物界面动力学的影响。通过使用具有炼金术步骤的分子动力学（MDAS）算法进行增强采样的分子动力学模拟来解释实验结果。实验结果表明，由于堆积密度增加，PE含量降低了脂质膜疏水核心附近酯羰基位置的氢键形成。观察到的脱水与界面区域内更快的分子动力学有关。
