School of Chemistry, UNSW Sydney, NSW 2052, Australia.
Australian Centre for Astrobiology, UNSW Sydney, NSW 2052, Australia.
Soft Matter. 2022 May 11;18(18):3498-3504. doi: 10.1039/d2sm00272h.
Connecting molecular interactions to emergent properties is a goal of physical chemistry, self-assembly, and soft matter science. We show that for fatty acid bilayers, vesicle rupture tension, and permeability to water and ions are coupled to pH alterations to lipid packing. A change in pH of one, for example, can halve the rupture tension of oleic acid membranes, an effect that is comparable to increasing lipid unsaturation in phospholipid systems. We use both experiments and molecular dynamics simulations to reveal that a subtle increase in pH can lead to increased water penetration, ion permeability, pore formation rates, and membrane disorder. For changes in membrane water content, oleic acid membranes appear to be more than a million times more sensitive to protons than to sodium ions. The work has implications for systems in which fatty acids are likely to be found, for example in the primitive cells on early Earth, biological membranes especially during digestion, and other biomaterials.
将分子相互作用与新兴性质联系起来是物理化学、自组装和软物质科学的目标。我们表明，对于脂肪酸双层膜，囊泡破裂张力以及对水和离子的通透性与脂质堆积的 pH 值变化有关。例如，pH 值的变化可以使油酸膜的破裂张力减半，这种效应与增加磷脂系统中脂质的不饱和度相当。我们使用实验和分子动力学模拟揭示了 pH 值的微小变化会导致水的渗透、离子通透性、孔形成速率和膜无序性增加。对于膜水含量的变化，油酸膜对质子的敏感性比钠离子高一百万倍以上。这项工作对于脂肪酸可能存在的系统具有重要意义，例如早期地球上的原始细胞、生物膜特别是在消化过程中以及其他生物材料。
