Tautomerism of a backbone protonated peptide revealed by soft X-ray action spectroscopy

The structure and reactivity of peptides can be influenced by their protonation state. Notably, protonation of the backbone can induce structural changes, such as tautomerism, shifting from the stable keto form to the enol form. This phenomenon, particularly in the backbone protonated peptide acetyl-pentaglycine, was examined using a combination of soft X-ray action spectroscopy at the nitrogen K-edge and theoretical calculations based on density functional theory (DFT). We identified a resonance at 400 eV that can be clearly attributed to π*(CN) transitions, linked exclusively to the enol form, as no keto form structures could replicate this resonance. These findings enhanced our understanding of the effect of protonation on the structure of peptides and could be employed for future dynamic studies.

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Journal
Physical Chemistry Chemical Physics
Published
2025-01-01
DOI
https://doi.org/10.1039/d5cp00506j
Primary Topic
Mass Spectrometry Techniques and Applications
Type
article
Field-Weighted Citation Impact
0.00

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article

Tautomerism of a backbone protonated peptide revealed by soft X-ray action spectroscopy

I. Unger, Lucas Schwob, Juliette Leroux, Kaja Schubert et al.
Physical Chemistry Chemical Physics
Mass Spectrometry Techniques and Applications
article

Tautomerism of a backbone protonated peptide revealed by soft X-ray action spectroscopy

I. Unger, Lucas Schwob, Juliette Leroux, Kaja Schubert, Florian Trinter, Sadia Bari, Carlos Ortiz‐Mahecha
article en

Abstract

The structure and reactivity of peptides can be influenced by their protonation state. Notably, protonation of the backbone can induce structural changes, such as tautomerism, shifting from the stable keto form to the enol form. This phenomenon, particularly in the backbone protonated peptide acetyl-pentaglycine, was examined using a combination of soft X-ray action spectroscopy at the nitrogen K-edge and theoretical calculations based on density functional theory (DFT). We identified a resonance at 400 eV that can be clearly attributed to π*(CN) transitions, linked exclusively to the enol form, as no keto form structures could replicate this resonance. These findings enhanced our understanding of the effect of protonation on the structure of peptides and could be employed for future dynamic studies.

Physical Chemistry Chemical PhysicsVol. 27(16)
Uppsala University (SE), Centre National de la Recherche Scientifique (FR), Universität Hamburg (DE), University of Groningen (NL), École Nationale Supérieure d'Ingénieurs de Caen (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Fritz Haber Institute of the Max Planck Society (DE), Deutsches Elektronen-Synchrotron DESY (DE), Centre de Recherche sur les Ions, les Matériaux et la Photonique (FR), Hamburg University of Technology (DE), Université de Caen Normandie (FR)
Deutsche Forschungsgemeinschaft, Région Normandie, Deutsches Elektronen-Synchrotron
Openalex Percentile: Top 94%
Mass Spectrometry Techniques and Applications
DOIOpen Access PDFOpenAlex
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