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Spectroscopic Evidence for Peptide-Bond-Selective Ultraviolet Photodissociation

Research output: Contribution to journalLetter

Aleksandr Y. Pereverzev, Zsuzsanna Koczor-Benda, Erik Saparbaev, Vladimir N. Kopysov, Edina Rosta, Oleg V. Boyarkin

Original languageEnglish
Pages (from-to)206-209
Number of pages4
JournalJournal of physical chemistry letters
Volume11
Issue number1
DOIs
Publication statusPublished - 2 Jan 2020

King's Authors

Abstract

We study the photodissociation induced by ultraviolet excitation of amide bonds in gas-phase protonated peptides. Jointly, mass spectrometry and cold ion spectroscopy provide evidence for a selective nonstatistical dissociation of specific peptide bonds in the spectral region of the formally forbidden n → π* transition of amide groups. Structural analysis reveals that the activation of this transition, peaked at 226 nm, originates from the nonplanar geometry of the bond. In contrast, the statistical dissociation in the electronic ground state appears to be the main outcome of the π → π* excitation of the peptide bonds at 193 nm. We propose a tentative model that explains the difference in the fragmentation mechanisms by the difference in localization of the electronic transitions and the higher amount of vibrational energy released in the electronic excited state upon absorption at 193 nm.

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