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Paper on "Photoelectron Circular Dichroism of Electrosprayed Gramicidin Anions" published in Journal of Physical Chemistry Letters

Peter Krüger*, Jon Henrik Both*, Uwe Linne*, Fabien Chirot**, and Karl-Michael Weitzel*

*   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

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.

J. Phys. Chem. Lett. 2022, 13, 6110−6116
Doi: https://doi.org/10.1021/acs.jpclett.2c01437