Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
J Chem Phys. 2017 Aug 28;147(8):085101. doi: 10.1063/1.4991871.
We present a joint experimental and computational study of the dynamic interactions of dialanine (Ala-Ala) with water, comparing the results of ultrafast 2D IR and infrared transient absorption spectroscopy of its amide I vibration with spectra modeled from molecular dynamics (MD) simulations. The experimental data are analyzed to describe vibrational frequency fluctuations, vibrational energy relaxation, and chemical exchange processes. The origin of these processes in the same underlying fluctuating forces allows a common description in terms of the fluctuations and conformational dynamics of the peptide and associated solvent. By comparing computational spectroscopy from MD simulations with multiple force fields and water models, we describe how the dynamics of water hydrogen bond fluctuations and switching processes act as a source of friction that governs the dephasing and vibrational relaxation, and provide a description of coupled water and peptide motions that give rise to spectroscopic exchange processes.
我们进行了一项联合实验和计算研究，研究了二丙氨酸（Ala-Ala）与水的动态相互作用，将酰胺 I 振动的超快 2D IR 和红外瞬态吸收光谱的结果与分子动力学（MD）模拟的光谱进行了比较。对实验数据进行了分析，以描述振动频率波动、振动能量弛豫和化学交换过程。这些过程在相同的基础波动力中的起源允许用肽和相关溶剂的波动和构象动力学来共同描述。通过比较来自 MD 模拟的计算光谱和多种力场和水模型，我们描述了水氢键波动和切换过程的动力学如何作为摩擦的来源，从而控制去相位和振动弛豫，并提供导致光谱交换过程的耦合水和肽运动的描述。
