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Combining UV photodissociation action spectroscopy with electron transfer dissociation for structure analysis of gas‐phase peptide cation‐radicals
Author(s) -
Shaffer Christopher J.,
Pepin Robert,
Tureček František
Publication year - 2015
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.3717
Subject(s) - chemistry , photodissociation , radical , electron transfer dissociation , photochemistry , dissociation (chemistry) , electron transfer , electron capture dissociation , spectroscopy , ion , mass spectrometry , tandem mass spectrometry , fourier transform ion cyclotron resonance , organic chemistry , physics , chromatography , quantum mechanics
We report the first example of using ultraviolet (UV) photodissociation action spectroscopy for the investigation of gas‐phase peptide cation‐radicals produced by electron transfer dissociation. z ‐Type fragment ions ● Gly‐Gly‐Lys + , coordinated to 18‐crown‐6‐ether (CE), are generated, selected by mass and photodissociated in the 200–400 nm region. The UVPD action spectra indicate the presence of valence‐bond isomers differing in the position of the C α radical defect, ( α ‐Gly)‐Gly‐Lys + (CE), Gly‐( α ‐Gly)‐Lys + (CE) and Gly‐Gly‐( α ‐Lys + )(CE). The isomers are readily distinguishable by UV absorption spectra obtained by time‐dependent density functional theory (TD‐DFT) calculations. In contrast, conformational isomers of these radical types are calculated to have similar UV spectra. UV photodissociation action spectroscopy represents a new tool for the investigation of transient intermediates of ion‐electron reactions. Specifically, z ‐type cation radicals are shown to undergo spontaneous hydrogen atom migrations upon electron transfer dissociation. Copyright © 2015 John Wiley & Sons, Ltd.