Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35043 Marburg, Germany.
Institut Lumière Matière, UMR5306 Université de Lyon, Université Lyon 1, CNRS, 5 rue de la Doua, 69100 Villeurbanne, France.
J Phys Chem Lett. 2022 Jul 7;13(26):6110-6116. doi: 10.1021/acs.jpclett.2c01437. Epub 2022 Jun 27.
Many sophisticated approaches for analyzing properties of chiral matter have been developed in recent years. But in general, the available chiroptical methods are limited to either solvated or small gaseous molecules. Studying the chirality of large biopolymers in the gas phase, including aspects of the secondary structure, becomes accessible by combining the electrospray ionization technique with chiroptical detection protocols. Here, laser-induced photodetachment from gramicidin anions, a peptide consisting of 15 amino acids has been investigated. The angular distribution of photoelectrons is demonstrated to be sensitive to the substitution of protons by cesium ions, which is accompanied by a conformational change. The photoelectron circular dichroism (PECD) is -0.5% for bare gramicidin, whereas gramicidin with several Cs ions attached exhibits a PECD of +0.5%. The results are complemented and supported by ion mobility studies. The presented approach offers the prospect of studying chirality and the secondary structure of various biopolymers.
近年来，已经开发出了许多用于分析手性物质性质的复杂方法。但是，一般来说，现有的手性光学方法仅限于溶剂化或小的气态分子。通过将电喷雾电离技术与手性检测方案相结合，可用于研究气相中大生物聚合物的手性，包括二级结构的各个方面。在这里，研究了由 15 个氨基酸组成的肽即短杆菌肽阴离子的激光诱导光电子分离。证明光电子的角分布对用铯离子替代质子敏感，这伴随着构象变化。裸短杆菌肽的光电子圆二色性（PECD）为-0.5％，而带有几个 Cs 离子的短杆菌肽则表现出+0.5％的 PECD。离子迁移率研究补充和支持了这些结果。所提出的方法为研究各种生物聚合物的手性和二级结构提供了前景。
