TY  - JOUR
AU  - Leroux, Juliette
AU  - Ortiz Mahecha, Carlos Andres
AU  - Schubert, Kaja
AU  - Trinter, Florian
AU  - Unger, Isaak
AU  - Schwob, Lucas
AU  - Bari, Sadia
TI  - Tautomerism of a backbone protonated peptide revealed by soft X-ray action spectroscopy
JO  - Physical chemistry, chemical physics
VL  - 27
SN  - 1463-9076
CY  - Cambridge
PB  - RSC Publ.
M1  - PUBDB-2025-00794
SP  - 8320 - 8326
PY  - 2025
AB  - 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<sup>*</sup>(C[double bond, length as m-dash]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. 
LB  - PUB:(DE-HGF)16
C6  - 40183417
UR  - <Go to ISI:>//WOS:001459353700001
DO  - DOI:10.1039/d5cp00506j
UR  - https://bib-pubdb1.desy.de/record/623828
ER  -