Chattopadhyay Madhurima, Krok Emilia, Orlikowska-Rzeznik Hanna, Piatkowski Lukasz
Institute of Physics, Poznan University of Technology Piotrowo 3 60-965 Poznan Poland
Chem Sci. 2023 Mar 22;14(15):4002-4011. doi: 10.1039/d2sc06836b. eCollection 2023 Apr 12.
Cellular membranes are surrounded by an aqueous buffer solution containing various ions, which influence the hydration layer of the lipid head groups. At the same time, water molecules hydrating the lipids play a major role in facilitating the organisation and dynamics of membrane lipids. Employing fluorescence microscopy imaging and fluorescence recovery after photobleaching measurements, we demonstrate that the cooperativity between water and sodium (Na) ions is crucial to maintain lipid mobility upon the removal of the outer hydration layer of the lipid membrane. Under similar hydration conditions, lipid diffusion ceases in the absence of Na ions. We find that Na ions (and similarly K ions) strengthen the water clathrate cage around the lipid phosphocholine headgroup and thus prevent its breaking upon removal of bulk water. Intriguingly, Ca and Mg do not show this effect. In this article, we provide a detailed molecular-level picture of ion specific dependence of lipid mobility and membrane hydration properties.
细胞膜被含有各种离子的水性缓冲溶液包围，这些离子会影响脂质头部基团的水化层。与此同时，使脂质水合的水分子在促进膜脂质的组织和动态变化方面发挥着重要作用。通过荧光显微镜成像和光漂白后荧光恢复测量，我们证明水和钠离子（Na）之间的协同作用对于在去除脂质膜的外部水化层后维持脂质流动性至关重要。在相似的水合条件下，没有钠离子时脂质扩散会停止。我们发现钠离子（以及类似的钾离子）会加强脂质磷酸胆碱头部基团周围的水笼包合物，从而防止在去除大量水时其破裂。有趣的是，钙和镁没有这种效果。在本文中，我们提供了脂质流动性和膜水合性质对离子特异性依赖性的详细分子水平图景。
