Bonn 2025 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 25: X-ray Spectroscopy

MO 25.5: Vortrag

Donnerstag, 13. März 2025, 15:45–16:00, HS XVI

Influence of a single water molecule on the X-ray absorption spectra of gas-phase phosphotyrosine — •Juliette Leroux^1,2,3, Jean-Yves Chesnel¹, Lucas Schwob², and Sadia Bari^2,4 — ¹CIMAP, University of Caen — ²Deutsches Elektronen-Synchrotron DESY — ³University of Hamburg — ⁴University of Groningen

The isolation of biomolecules in the gas phase removes all interactions with the solvent and enables stepwise control of these interactions by progressively increasing the number of bound water molecules, ultimately bridging the gap between isolated molecules and aqueous conditions. Already, a single water molecule can induce significant structural changes in the molecule, such as the location of the protonation site. Over the last thirty years, there have been efforts to develop experimental techniques to study hydrated species in the gas phase using an electrospray ionization source.

To study the effect of hydration on the structure of biomolecules, our technique of choice is near-edge X-ray absorption mass spectrometry (NEXAMS). NEXAMS provides a local probe into the atomic environment and is based on the electronic excitations of core electrons to unoccupied molecular orbitals, thus capturing the electronic and geometric structure of the system under investigation. In this context, we studied the influence of a single water molecule on the structure and radiation-induced fragmentation of protonated phosphotyrosine. In particular, I will discuss the results we obtained at the carbon and oxygen K-edges in comparison with density functional theory calculations to decipher the structure of singly hydrated phosphotyrosine.

Keywords: Soft X-ray spectroscopy; Electrospray ionisation source; nanosolvation