Schlamadinger Diana E, Leigh Brian S, Kim Judy E
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
J Raman Spectrosc. 2012 Oct;43(10):1459-1464. doi: 10.1002/jrs.4061.
Aromatic interactions are important stabilizing forces in proteins but are difficult to detect in the absence of high-resolution structures. Ultraviolet resonance Raman spectroscopy is used to probe the vibrational signatures of aromatic interactions in TrpZip2, a synthetic β-hairpin peptide that is stabilized by edge-to-face and face-to-face tryptophan π-π interactions. The vibrational markers of isolated edge-to-face π-π interactions are investigated in the related β-hairpin peptide W2W11. The bands that comprise the Fermi doublet exhibit systematic shifts in position and intensity for TrpZip2 and W2W11 relative to the model peptide, W2W9, which does not form aromatic interactions. Additionally, hypochromism of the B absorption band of tryptophan in TrpZip2 leads to a decrease in the relative Raman cross-sections of B-coupled Raman bands. These results reveal spectral markers for stabilizing tryptophan π-π interactions and indicate that ultraviolet resonance Raman may be an important tool for the characterization of these biological forces.
芳香相互作用是蛋白质中重要的稳定作用力，但在缺乏高分辨率结构的情况下难以检测。紫外共振拉曼光谱用于探测TrpZip2中芳香相互作用的振动特征，TrpZip2是一种合成的β-发夹肽，通过边对面和面对面的色氨酸π-π相互作用而稳定。在相关的β-发夹肽W2W11中研究了孤立的边对面π-π相互作用的振动标记。相对于不形成芳香相互作用的模型肽W2W9，构成费米双峰的谱带在TrpZip2和W2W11中的位置和强度呈现系统性变化。此外，TrpZip2中色氨酸B吸收带的减色导致B耦合拉曼谱带的相对拉曼截面减小。这些结果揭示了稳定色氨酸π-π相互作用的光谱标记，并表明紫外共振拉曼可能是表征这些生物作用力的重要工具。
