Department of Chemistry, Stanford University, Stanford, California 94305, USA.
J Phys Chem B. 2012 Sep 13;116(36):11024-31. doi: 10.1021/jp304058x. Epub 2012 Aug 29.
The changes in fast dynamics of HP35 with a double CN vibrational dynamics label (HP35-P(2)) as a function of the extent of denaturation by urea were investigated with two-dimensional infrared (2D IR) vibrational echo spectroscopy. Cyanophenylalanine (PheCN) replaces the native phenylalanine at two residues in the hydrophobic core of HP35, providing vibrational probes. NMR data show that HP35-P(2) maintains the native folded structure similar to wild type and that both PheCN residues share essentially the same environment within the peptide. A series of time-dependent 2D IR vibrational echo spectra were obtained for the folded peptide and the increasingly unfolded peptide. Analysis of the time dependence of the 2D spectra yields the system's spectral diffusion, which is caused by the sampling of accessible structures of the peptide under thermal equilibrium conditions. The structural dynamics become faster as the degree of unfolding is increased.
用二维红外（2D IR）振动回波光谱法研究了带有双 CN 振动动力学标签（HP35-P(2)）的 HP35 快速动力学变化与脲变性程度的关系。氰基苯丙氨酸（PheCN）取代了 HP35 疏水核心中两个残基的天然苯丙氨酸，提供了振动探针。NMR 数据表明，HP35-P(2) 保持了与野生型相似的天然折叠结构，并且两个 PheCN 残基在肽内基本上具有相同的环境。为折叠肽和逐渐去折叠的肽获得了一系列时变 2D IR 振动回波光谱。对 2D 光谱的时间依赖性的分析产生了系统的光谱扩散，这是由于在热平衡条件下对肽的可及结构进行了采样。随着去折叠程度的增加，结构动力学变得更快。
