Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada.
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Soft Matter. 2023 Jul 5;19(26):5001-5015. doi: 10.1039/d2sm01583h.
Cellular membranes are responsible for absorbing the effects of external perturbants for the cell's survival. Such perturbants include small ubiquitous molecules like -alcohols which were observed to exhibit anesthetic capabilities, with this effect tapering off at a cut-off alcohol chain length. To explain this cut-off effect and complement prior biochemical studies, we investigated a series of -alcohols (with carbon lengths 2-18) and their impact on several bilayer properties, including lipid flip-flop, intervesicular exchange, diffusion, membrane bending rigidity and more. To this end, we employed an array of biophysical techniques such as time-resolved small angle neutron scattering (TR-SANS), small angle X-ray scattering (SAXS), all atomistic and coarse-grained molecular dynamics (MD) simulations, and calcein leakage assays. At an alcohol concentration of 30 mol% of the overall lipid content, TR-SANS showed 1-hexanol (C6OH) increased transverse lipid diffusion, flip-flop. As alcohol chain length increased from C6 to C10 and longer, lipid flip-flop slowed by factors of 5.6 to 32.2. Intervesicular lipid exchange contrasted these results with only a slight cut-off at alcohol concentrations of 30 mol% but not 10 mol%. SAXS, MD simulations, and leakage assays revealed changes to key bilayer properties, such as bilayer thickness and fluidity, that correlate well with the effects on lipid flip-flop rates. Finally, we tie our results to a defect-mediated pathway for alcohol-induced lipid flip-flop.
细胞膜负责吸收细胞生存所需的外部扰动因素的影响。这些扰动因素包括像醇这样的普遍存在的小分子,它们被观察到具有麻醉能力,这种效应在醇链长度的截止处逐渐减弱。为了解释这种截止效应,并补充先前的生化研究,我们研究了一系列 - 醇(碳链长度为 2-18)及其对几种双层性质的影响,包括脂质翻转、囊泡间交换、扩散、膜弯曲刚性等。为此,我们采用了一系列生物物理技术,如时间分辨小角中子散射(TR-SANS)、小角 X 射线散射(SAXS)、全原子和粗粒分子动力学(MD)模拟以及钙黄绿素渗漏测定。在醇浓度为总脂质含量的 30 mol%时,TR-SANS 显示 1-己醇(C6OH)增加了横向脂质扩散和翻转。随着醇链长度从 C6 增加到 C10 及更长,脂质翻转的速度减慢了 5.6 到 32.2 倍。囊泡间脂质交换与这些结果形成对比,仅在醇浓度为 30 mol%而不是 10 mol%时出现轻微截止。SAXS、MD 模拟和渗漏测定揭示了关键双层性质的变化,如双层厚度和流动性,这些性质与脂质翻转速率的变化密切相关。最后,我们将我们的结果与缺陷介导的醇诱导脂质翻转途径联系起来。