Berlin 2024 – scientific programme
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BP: Fachverband Biologische Physik
BP 10: Computational Biophysics II
BP 10.10: Talk
Tuesday, March 19, 2024, 12:15–12:30, H 0112
Transition intensities decomposition for π−π interaction of X-ray absorption for proteins — •Carlos Ortiz-Mahecha1, Lucas Schwob2, Sadia Bari2, and Robert Meissner1, 3 — 1Technische Universität Hamburg — 2Deutsches Elektronen-Synchrotron (DESY) — 3Helmholtz-Zentrum Hereon
π-π stacking between aromatic side chains leads to structure stabilization in proteins, which could be studied by X-ray absorption spectroscopy (XAS) and quantum mechanical (QM) calculations. Access to such excited state calculations for proteins is quite challenging due to their computational cost. In order to decompose the XAS spectra of proteins into a sum of smaller constituents, we propose that the inner-shell transition intensities of aromatic amino acids can be correlated with the charge transfer occurring in the π-π* interactions. We therefore propose a theoretical analysis to decompose the XAS spectra transition intensities into their atomistic contributions in order to derive distance thresholds for the core-to-valence transition between aromatic amino acid pairs in proteins.
We found that the intertransition intensities and the charge transfer energy can be correlated, enabling intermolecular properties to be associated with core-electron excited-state properties. We suggest that, for XAS in proteins, the electronic neighbourhood influence of the high conjugated electronic density of the aromatic amino acid interactions can be inferred by evaluating the charge transfer between them. This can be used as a criterion to define smaller constituents in a proteins by the charge transfer of the aromatic amino acid interactions.
Keywords: X-ray absorption for proteins; 𝜋-𝜋 stacking in aromatic amino acids; Transition intensities; Charge transfer energy; Excited state properties