Yamada Takeshi, Takahashi Nobuaki, Tominaga Taiki, Takata Shin-Ichi, Seto Hideki
Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS) , 162-1 Shirakata, Tokai, Naka, Ibaraki, Japan 319-1106.
Institute for Chemical Research, Kyoto University Gokasho , Uji, Kyoto, Japan 611-0011.
J Phys Chem B. 2017 Sep 7;121(35):8322-8329. doi: 10.1021/acs.jpcb.7b01276. Epub 2017 Aug 23.
The dynamical behavior of hydration water sandwiched between 1,2-dimyristyl-sn-glycero-3-phosphocholine (DMPC) bilayers was investigated by quasi-elastic neutron scattering (QENS) in the range between 275 and 316 K, where the main transition temperature of DMPC is interposed. The results revealed that the hydration water could be categorized into three types of water: (1) free water, whose dynamical behavior is slightly different from that of bulk water; (2) loosely bound water, whose dynamical behavior is 1 order of magnitude slower than that of the free water; and (3) tightly bound water, whose dynamical behavior is comparable with that of DMPC molecules. The number of loosely bound and tightly bound water molecules per DMPC molecule monotonically decreased and increased with decreasing temperature, respectively, and the sum of these water molecules remained constant. The number of free water molecules per DMPC molecule was constant in the measured temperature range.
通过准弹性中子散射（QENS）研究了夹在1,2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）双层之间的水化水在275至316 K范围内的动力学行为，该温度范围介于DMPC的主要转变温度之间。结果表明，水化水可分为三种类型的水：（1）自由水，其动力学行为与体相水略有不同；（2）松散结合水，其动力学行为比自由水慢1个数量级；（3）紧密结合水，其动力学行为与DMPC分子相当。每个DMPC分子的松散结合水和紧密结合水分子数量分别随温度降低而单调减少和增加，且这些水分子的总数保持不变。在测量的温度范围内，每个DMPC分子的自由水分子数量是恒定的。
