DeCamp M F, DeFlores L, McCracken J M, Tokmakoff A, Kwac K, Cho M
Department of Chemistry and George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Phys Chem B. 2005 Jun 2;109(21):11016-26. doi: 10.1021/jp050257p.
The vibrational frequency of the amide I transition of peptides is known to be sensitive to the strength of its hydrogen bonding interactions. In an effort to account for interactions with hydrogen bonding solvents in terms of electrostatics, we study the vibrational dynamics of the amide I coordinate of N-methylacetamide in prototypical polar solvents: D2O, CDCl3, and DMSO-d6. These three solvents have varying hydrogen bonding strengths, and provide three distinct solvent environments for the amide group. The frequency-frequency correlation function, the orientational correlation function, and the vibrational relaxation rate of the amide I vibration in each solvent are retrieved by using three-pulse vibrational photon echoes, two-dimensional infrared spectroscopy, and pump-probe spectroscopy. Direct comparisons are made to molecular dynamics simulations. We find good quantitative agreement between the experimentally retrieved and simulated correlation functions over all time scales when the solute-solvent interactions are determined from the electrostatic potential between the solvent and the atomic sites of the amide group.
已知肽的酰胺I跃迁的振动频率对其氢键相互作用的强度敏感。为了从静电学角度解释与氢键溶剂的相互作用，我们研究了N-甲基乙酰胺的酰胺I坐标在典型极性溶剂：D2O、CDCl3和DMSO-d6中的振动动力学。这三种溶剂具有不同的氢键强度，并为酰胺基团提供了三种不同的溶剂环境。通过使用三脉冲振动光子回波、二维红外光谱和泵浦-探测光谱，获取了每种溶剂中酰胺I振动的频率-频率相关函数、取向相关函数和振动弛豫率。并与分子动力学模拟进行了直接比较。当根据溶剂与酰胺基团原子位点之间的静电势确定溶质-溶剂相互作用时，我们发现在所有时间尺度上，实验获取的相关函数与模拟的相关函数之间存在良好的定量一致性。
