Faculty of Chemistry, Jagiellonian Chemistry, Ingardena 3, 30-060 Krakow, Poland.
J Phys Chem B. 2012 Feb 2;116(4):1414-25. doi: 10.1021/jp208586j. Epub 2012 Jan 25.
Three dipeptides containing dehydroresidues (ΔAla, Δ((Z))Phe, and Δ((E))Phe) were examined by IR, Raman, and surface-enhanced Raman techniques for the first time. The effect of the size and isomer type of the β-substituent in the dehydroresidue on the conformational structure of the peptide was evaluated by using the analysis of IR and Raman bands. Additionally, SERS spectroscopy provided insight into the adsorption mechanism of these species on the metal surface. SERS spectra were recorded at alkaline pH on the silver sol using visible light excitation. The dehydroresidues studied here strongly influenced the SERS profile of the peptides. The most pronounced SERS signal for all dipeptides was assigned to the symmetric stretching vibration of the carboxylate ions. This indicates that the dehydropeptides studied here primarily adsorb via the deprotonated carboxylic group. Additionally, the enhanced SERS bands in the range 1550-1650 cm(-1) show differences in contribution of the dehydroresidue to the adsorption mechanism of the studied peptides.
三种含有脱氢残基（ΔAla、Δ((Z))Phe 和 Δ((E))Phe）的二肽首次通过红外、拉曼和表面增强拉曼技术进行了研究。通过分析红外和拉曼带，评估了β-取代基在脱氢残基中的大小和异构体类型对肽构象结构的影响。此外，SERS 光谱提供了对这些物种在金属表面上吸附机制的深入了解。在碱性 pH 下，使用可见光激发在银溶胶上记录 SERS 光谱。研究中发现的脱氢残基强烈影响了肽的 SERS 图谱。所有二肽的最强 SERS 信号都归因于羧酸离子的对称伸缩振动。这表明研究中的脱氢肽主要通过脱质子羧酸基团吸附。此外，在 1550-1650 cm(-1)范围内增强的 SERS 带显示了脱氢残基对研究中肽吸附机制的贡献的差异。
