Dresden 2026 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Focus Session: Water – from Atmosphere to Space II (joint session CPP/DY)

DY 24.4: Vortrag

Dienstag, 10. März 2026, 12:00–12:15, ZEU/LICH

Calcium-amino acid complexation in water probed by Intermolecular Coulombic Decay — •Michele Pugini, Nicolas Velasquez, Harmanjot Kaur, Florian Trinter, Qi Zhou, Lukas Tomaník, Uwe Hergenhahn, and Bernd Winter — Fritz-Haber-Institut, Berlin

The Ca2+ ion is the most abundant metal ion in the human body, playing essential roles in numerous biological processes, many of which involve interactions with proteins. Gaining molecular-level insight into the nature of the interaction between Ca2+ ions and solvated amino acids is therefore crucial for understanding calcium's biological function. Intermolecular Coulombic decay (ICD), a non-local autoionization process, offers unique sensitivity to the local chemical environment and can selectively probe interactions within the first solvation shell of solvated Ca2+ ions.

Here, we demonstrate the sensitivity of resonant ICD3 to the chemical composition of the solvation shell, enabling the identification of Ca2+ associations with specific amino acids. Our model system is the amino acid proline. The interaction, if present, is revealed via the ICD electrons resulting from the ionization of the biomolecule upon the 2p to 3d excitation of Ca2+.

Our results unequivocally identify Ca2+-proline interactions, indicating substitution of water molecules in the ion's coordination shell by proline. These findings establish ICD as a sensitive probe of metal-biomolecule interactions and highlight its potential as a powerful spectroscopic tool for investigating biomolecular structure in solution.

Keywords: Intermolecular Coulombic Decay; amino acid-metal interaction; proline; calcium