Nanomechanics of Lipid Bilayers: Heads or Tails?
Nanomechanics of Lipid Bilayers: Heads or Tails?
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DOI：
10.1021/ja1002185
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发表时间：
2010-09-22
影响因子：
15
通讯作者：
Sanz, Fausto
中科院分区：
文献类型：
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作者：
Garcia-Manyes, Sergi;Redondo-Morata, Lorena;Sanz, Fausto
了解机械应力对细胞膜的影响在生物物理学中是至关重要的。在这里，我们使用力谱AFM定量表征支持的脂质双层的纳米机械稳定性作为其化学组成的函数。塑性变形的发生揭示了其本身作为接近力曲线中的重复跳跃，其代表了双层机械稳定性的分子指纹。通过系统地探测一组化学上不同的支撑脂质双层（SLB），我们首先表明，头基和尾部对其机械性能有决定性的影响。当在链中引入每个额外的-CH 2-时，探测的SLB的机械稳定性线性增加3.3 nN，它表现出对磷脂头基的显著依赖性，范围从DPPA的3 nN到DPPG的66 nN。此外，我们还定量的膜的机械稳定性的减少作为非极性尾部的化学结构中的不饱和和分子分支的数量的函数。最后，我们证明，在引入胆固醇和麦角固醇，相反，以前的信念膜的机械稳定性不仅线性增加，在液相（DLPC），但也为磷脂存在于凝胶相（DPPC）。我们的结果进行了讨论的连续形核模型的框架。这项工作突出了磷脂分子化学结构的微妙变化对膜反应的引人注目的影响，当暴露于机械力时，这是自然界中常见的机制。
Understanding the effect of mechanical stress on membranes is of primary importance in biophysics. Here we use force spectroscopy AFM to quantitatively characterize the nanomechanical stability of supported lipid bilayers as a function of their chemical composition. The onset of plastic deformation reveals itself as a repetitive jump in the approaching force curve, which represents a molecular fingerprint for the bilayer mechanical stability. By systematically probing a set of chemically distinct supported lipid bilayers (SLBs), we first show that both the headgroup and tail have a decisive effect on their mechanical properties. While the mechanical stability of the probed SLBs linearly increases by 3.3 nN upon the introduction of each additional -CH2- in the chain, it exhibits a significant dependence on the phospholipid headgroup, ranging from 3 nN for DPPA to 66 nN for DPPG. Furthermore, we also quantify the reduction of the membrane mechanical stability as a function of the number of unsaturations and molecular branching in the chemical structure of the apolar tails. Finally, we demonstrate that, upon introduction of cholesterol and ergosterol, contrary to previous belief the mechanical stability of membranes not only increases linearly in the liquid phase (DLPC) but also for phospholipids present in the gel phase (DPPC). Our results are discussed in the framework of the continuum nucleation model. This work highlights the compelling effect of subtle variations in the chemical structure of phospholipid molecules on the membrane response when exposed to mechanical forces, a mechanism of common occurrence in nature.