Meineke Jakob, Weik Martin, Zaccai Giuseppe, Fragneto Giovanna
University of Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Grenoble, France.
Institut Laue-Langevin, Grenoble, France.
Front Chem. 2020 Jun 18;8:455. doi: 10.3389/fchem.2020.00455. eCollection 2020.
Neutron diffraction was used to study the behavior of water present in phospholipid multilamellar stacks from 1,2-dimyristoyl--glycero-3-phosphatidylcholine (DMPC) at cryogenic temperatures. Evidence was found for the existence of a highly viscous phase of water that exists between 180 and 220 K based on the observation that water can leave the intermembrane space at these low temperatures. Similar measurements are described in the literature for purple membrane (PM) samples. From a comparison with results from this natural membrane by using the same flash-cooling protocol, it is found that in the case of pure lipid samples, less water is trapped and the water flows out at lower temperatures. This suggests that the water is less hindered in its movements than in the PM case. It is shown that at least the Lβ'-phase of DMPC can be trapped likely by flash cooling; upon heating to about 260 K, it transforms to another phase that was not fully characterized.
利用中子衍射研究了1,2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）磷脂多层堆叠体中存在的水在低温下的行为。基于在这些低温下水能够离开膜间空间的观察结果，发现存在一个高度粘稠的水相，其存在于180至220K之间。文献中描述了对紫膜（PM）样品进行的类似测量。通过使用相同的快速冷却方案与该天然膜的结果进行比较，发现在纯脂质样品的情况下，截留的水较少，并且水在较低温度下流出。这表明水在其运动中受到的阻碍比在PM的情况下要小。结果表明，至少DMPC的Lβ'相可能通过快速冷却被截留；加热到约260K时，它转变为另一个未完全表征的相。
