Institut Laue-Langevin, Grenoble, 38000, France.
Phys Rev Lett. 2019 Jun 21;122(24):248101. doi: 10.1103/PhysRevLett.122.248101.
Time- and temperature-resolved neutron reflectometry allowed us to perform the real-time characterization of the structural changes taking place across phase transitions in solid supported-lipid bilayers (SLBs). We identified the presence of an isothermal phase transition, characterized by a symmetrical rearrangement of lipid molecules in both bilayer leaflets, followed by the main thermotropic phase transition, and characterized by an independent melting of the two leaflets. We demonstrated that the presence of a substrate increases the enthalpy of melting by the same amount for both SLB leaflets with respect to the values reported for freestanding bilayers. These results are highly relevant for the further understanding of cooperative structural dynamics in SLBs and for the investigation of thermally activated processes such as the transmembrane lipid translocation (flip flop).
时间和温度分辨中子反射率测量使我们能够实时表征固载脂质双层（SLB）中相变过程中发生的结构变化。我们发现存在等温相变，其特征是双层各叶中脂质分子的对称重排，随后是主要的热致相变，其特征是两个叶的独立熔融。我们证明，与自由双层相比，衬底的存在使两个 SLB 叶的熔融焓增加了相同的量。这些结果对于进一步理解 SLB 中的协同结构动力学以及研究热激活过程（如跨膜脂质转位（翻转））非常重要。
