Missing Amide I Mode in Gap-Mode Tip-Enhanced Raman Spectra of Proteins
Missing Amide I Mode in Gap-Mode Tip-Enhanced Raman Spectra of Proteins
复制标题
DOI：
10.1021/jp306831p
复制
发表时间：
2012-11-01
影响因子：
3.7
通讯作者：
Zenobi, Renato
中科院分区：
文献类型：
--
作者：
Blum, Carolin;Schmid, Thomas;Zenobi, Renato
针尖增强拉曼光谱是一种结合了扫描探针显微镜和拉曼光谱优点的表面灵敏分析方法。它为生物样品成像提供了很大的希望，具有高空间分辨率（10-50 nm），远低于光学衍射极限。它提供了直接定位和鉴定蛋白质及其在复合物中的构象的机会（例如，原生）环境。尖端增强拉曼。(TER)在所谓的“间隙模式”的配置与金属尖端扫描隧道反馈与金属基板涂有不同的蛋白质（牛血清白蛋白，免疫球蛋白G，胰蛋白酶，β-乳球蛋白）以及模型八肽（有和没有一个芳香族氨基酸残基）的光谱。目标是确定是否有可能可靠地分配蛋白质的标记带，以及蛋白质的不同二级结构是否可以在其间隙模式TER光谱中与IR和常规拉曼光谱一样可靠地区分。结果表明，与传统的蛋白质拉曼光谱相反，酰胺I模式，这是广泛用于识别蛋白质的二级结构基序，是不可见的缺口模式TEAS。芳香模式是突出的，可以用作在复杂环境中的蛋白质成像的可靠标记带。
Tip-enhanced Raman spectroscopy is a surface sensitive analytical method that combines the advantages of scanning probe microscopy and Raman spectroscopy. It holds great promises for imaging of biological samples with high spatial resolution (10-50 nm), well below the optical diffraction limit. It offers the opportunity to directly localize and identify proteins and their conformation in a complex (e.g., native) environment. Tip-enhanced Raman.(TER) spectra in the so-called "gap-mode" configuration with a metal tip in scanning tunnelling feedback with a metal substrate coated with different proteins (bovine serum albumin, immunoglobulin G, trypsin, and beta-lactoglobulin) as well as of model octapeptides (with and without an aromatic amino acid residue) are presented. The goal was to determine if it is possible to reliably assign marker bands for proteins and if different secondary structures of proteins can be distinguished in their gap-mode TER spectra as reliably as by IR and conventional Raman spectroscopy. It is shown that contrary to the presented conventional Raman spectra of proteins the amide I mode, which is widely used to identify secondary structure motifs of proteins, is not visible in gap-mode TEAS. Aromatic modes are prominent and can be used as reliable marker bands for imaging of proteins in a complex environment.