Experimentelle Physik VII, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany.
Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , 4505 Maryland Parkway, Las Vegas, Nevada 89154-4003, United States.
J Phys Chem B. 2017 Jul 13;121(27):6549-6556. doi: 10.1021/acs.jpcb.7b04291. Epub 2017 Jun 28.
Nonresonant N K, O K, C K, and S L X-ray emission spectra of the 20 most common proteinogenic amino acids in their solid zwitterionic form are reported. They represent a comprehensive database that can serve as a reliable basis for the X-ray absorption spectroscopy (XES) studies of peptides and proteins. At the most important N and O K edges, clear similarities and differences between the spectra of certain amino acids are observed and associated with the specific chemical structure of these molecules and their functional groups. Analysis of these spectra allows the generation of spectral fingerprints of the protonated amino group, the deprotonated carboxylic group, and, using a building block approach, the specific nitrogen- and oxygen-containing functional groups in the side chains of the amino acids. Some of these fingerprints are compared to the spectra of reference compounds with the respective functional groups; they exhibit reasonable similarity, underlining the validity of the spectral fingerprint approach. The C K and S L XES spectra are found to be specific for each amino acid, in accordance with the different local environments of the involved C and S atoms, respectively.
报告了 20 种最常见的蛋白质氨基酸在其固体两性离子形式下的非共振 N K、O K、C K 和 S L X 射线发射光谱。它们代表了一个全面的数据库，可以作为肽和蛋白质的 X 射线吸收光谱（XES）研究的可靠基础。在最重要的 N 和 O K 边缘，观察到某些氨基酸的光谱之间存在明显的相似和差异，并与这些分子的特定化学结构及其官能团相关。对这些光谱的分析允许生成质子化氨基、去质子化羧酸基的光谱指纹，以及使用积木方法生成氨基酸侧链中特定的含氮和含氧官能团的光谱指纹。其中一些指纹与具有相应官能团的参考化合物的光谱进行了比较；它们表现出合理的相似性，突出了光谱指纹方法的有效性。C K 和 S L XES 光谱分别与涉及的 C 和 S 原子的不同局部环境相对应，被发现对每种氨基酸都是特异的。
