Institute of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo náměstí 2, 16610, Prague, Czech Republic.
Department of Analytical Chemistry, University of Chemistry and Technology, Technická 5, 16628, Prague, Czech Republic.
Chemistry. 2018 Jun 18;24(34):8664-8669. doi: 10.1002/chem.201800840. Epub 2018 May 22.
Lanthanide complexes are used as convenient spectroscopic probes for many biomolecules. Their binding to proteins is believed to be enhanced by the presence of histidine, but the strength of the interaction significantly varies across different systems. To understand the role of peptide length and sequence, short histidine-containing peptides have been synthesized (His-Gly, His-Gly-Gly, His-Gly-Gly-Gly, Gly-His, Gly-His-Gly, His-His, and Gly-Gly-His) and circularly polarized luminescence (CPL) induced at the [Eu(dpa) ] complex has been measured by means of a Raman optical activity (ROA) spectrometer. The obtained data indicate relatively weak binding of the histidine residue to the complex, with a strong participation of other parts of the peptide. Longer peptides, low pH, and a histidine residue close to the N-peptide terminus favor the binding. The binding strengths are approximately proportional to the CPL intensity and roughly correlate with predictions based on molecular dynamics (MD) simulations. The specificity of lanthanide binding to the peptide structure and its intense luminescence and high optical activity make the ROA/CPL technique suitable for probing secondary and tertiary structures of peptides and proteins.
镧系配合物被用作许多生物分子的方便光谱探针。据信，组氨酸的存在增强了它们与蛋白质的结合，但不同体系之间的相互作用强度有很大差异。为了了解肽长度和序列的作用，已经合成了含有短组氨酸的肽（His-Gly、His-Gly-Gly、His-Gly-Gly-Gly、Gly-His、Gly-His-Gly、His-His 和 Gly-Gly-His），并通过拉曼光学活性（ROA）光谱仪测量了[Eu（dpa）]配合物诱导的圆偏振发光（CPL）。所获得的数据表明组氨酸残基与配合物的结合较弱，肽的其他部分强烈参与。较长的肽、较低的 pH 值和靠近 N-肽末端的组氨酸残基有利于结合。结合强度与 CPL 强度大致成正比，并与基于分子动力学（MD）模拟的预测大致相关。镧系元素与肽结构的特异性结合以及其强烈的发光和高光学活性使得 ROA/CPL 技术适合于探测肽和蛋白质的二级和三级结构。
