Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, 230026, Hefei, China.
Nat Commun. 2019 Mar 1;10(1):1010. doi: 10.1038/s41467-019-08899-3.
The influence of hydration water on the vibrational energy relaxation in a protein holds the key to understand ultrafast protein dynamics, but its detection is a major challenge. Here, we report measurements on the ultrafast vibrational dynamics of amide I vibrations of proteins at the lipid membrane/HO interface using femtosecond time-resolved sum frequency generation vibrational spectroscopy. We find that the relaxation time of the amide I mode shows a very strong dependence on the HO exposure, but not on the DO exposure. This observation indicates that the exposure of amide I bond to HO opens up a resonant relaxation channel and facilitates direct resonant vibrational energy transfer from the amide I mode to the HO bending mode. The protein backbone motions can thus be energetically coupled with protein-bound water molecules. Our findings highlight the influence of HO on the ultrafast structure dynamics of proteins.
水合对蛋白质中振动能量弛豫的影响是理解超快蛋白质动力学的关键，但对其的检测是一个重大挑战。在这里，我们报告了使用飞秒时间分辨和频产生振动光谱在脂质膜/HO 界面上蛋白质的酰胺 I 振动的超快振动动力学的测量结果。我们发现，酰胺 I 模式的弛豫时间对 HO 的暴露表现出很强的依赖性，但对 DO 的暴露没有依赖性。这一观察结果表明，酰胺 I 键对 HO 的暴露开辟了一个共振弛豫通道，有利于从酰胺 I 模式到 HO 弯曲模式的直接共振振动能量转移。因此，蛋白质的骨架运动可以与蛋白质结合的水分子进行能量耦合。我们的研究结果突出了 HO 对蛋白质超快结构动力学的影响。
