Van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
Phys Chem Chem Phys. 2018 Mar 7;20(10):6996-7006. doi: 10.1039/c8cp00170g.
We report on a molecular dynamics study on the relation between the structure and the orientational (and hydrogen bond) dynamics of hydration water around the ocean pout AFP III anti-freeze protein. We find evidence for an increasing tetrahedral structure from the area opposite to the ice binding site (IBS) towards the protein IBS, with the strongest signal of tetrahedral structure around the THR-18 residue of the IBS. The tetrahedral structural parameter mostly positively correlates with increased reorientation decay times. Interestingly, for several key (polar) residues that are not part of the IBS but are in its vicinity, we observe a decrease of the reorientation time with increasing tetrahedral structure. A similar anti-correlation is observed for the hydrogen-bonded water molecules. These effects are enhanced at a lower temperature. We interpret these results in terms of the structure-making and structure-breaking residues. Moreover, we investigate the tetrahedral structure and dynamics of waters at a partially dehydrated IBS, and for the protein adsorbed at the air-water interface. We find that the mutation changes the preferred protein orientation upon adsorption at an air-water interface. These results are in agreement with the water-air Vibration Sum Frequency Generation spectroscopic experiments showing a strongly reduced tetrahedral signal upon mutation at the IBS.
我们报告了一项分子动力学研究，研究了海洋鲈 AFP III 抗冻蛋白周围水合水的结构与取向（和氢键）动力学之间的关系。我们发现，从与冰结合位点（IBS）相对的区域到 IBS 附近的蛋白质，四面体结构逐渐增加，IBS 中 THR-18 残基周围的四面体结构信号最强。四面体结构参数与重新取向的衰减时间的增加呈正相关。有趣的是，对于几个不在 IBS 但在其附近的关键（极性）残基，我们观察到随着四面体结构的增加，重新取向时间减少。对于氢键合的水分子，也观察到类似的反相关。在较低温度下，这些效应会增强。我们根据结构形成和破坏残基来解释这些结果。此外，我们还研究了部分脱水 IBS 处水的四面体结构和动力学，以及吸附在气-水界面上的蛋白质。我们发现，突变改变了在气-水界面吸附时蛋白质的优先取向。这些结果与水-空气的振动和频产生光谱实验一致，该实验表明在 IBS 突变时，四面体信号大大降低。
