Characterization of Antigenic Oligosaccharides from Gram-Negative Bacteria via Activated Electron Photodetachment Mass Spectrometry

Christopher M. Crittenden, Edwin E. Escobar, Peggy E. Williams, James D. Sanders, Jennifer Brodbelt

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Lipooligosaccharides (LOS), composed of hydrophilic oligosaccharides and hydrophobic lipid A domains, are found on the outer membranes of Gram-negative bacteria. Here we report the characterization of deacylated LOS of LPS by activated-electron photodetachment mass spectrometry. Collision induced dissociation (CID) of these phosphorylated oligosaccharides produces simple MS/MS spectra with most fragment ions arising from cleavages near the reducing end of the molecule where the phosphate groups are located. In contrast, 193 nm ultraviolet photodissociation (UVPD) generates a wide array of product ions throughout the oligosaccharide including cross-ring fragments that illuminate the branching patterns. However, there are also product ions that are redundant or uninformative, resulting in more congested spectra that complicate interpretation. In this work, a hybrid UVPD-CID approach known as activated-electron photodetachment (a-EPD) affords less congested spectra than UVPD alone and richer fragmentation patterns than CID alone. a-EPD combines UVPD of negatively charged oligosaccharides to yield abundant charge-reduced radical ions which are subsequently interrogated by collisional activation. CID of the charge-reduced precursors results in extensive fragmentation throughout the backbone of the oligosaccharide. This hybridized a-EPD approach was employed to characterize the structure and branching pattern of deacylated LOS of E. coli.

Original languageEnglish (US)
Pages (from-to)4672-4679
Number of pages8
JournalAnalytical Chemistry
Volume91
Issue number7
DOIs
StatePublished - Apr 2 2019

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Photodissociation
Oligosaccharides
Mass spectrometry
Bacteria
Electrons
Ions
Lipid A
Escherichia coli
Chemical activation
Phosphates
Membranes
Molecules
lipid-linked oligosaccharides

ASJC Scopus subject areas

  • Analytical Chemistry

Cite this

Characterization of Antigenic Oligosaccharides from Gram-Negative Bacteria via Activated Electron Photodetachment Mass Spectrometry. / Crittenden, Christopher M.; Escobar, Edwin E.; Williams, Peggy E.; Sanders, James D.; Brodbelt, Jennifer.

In: Analytical Chemistry, Vol. 91, No. 7, 02.04.2019, p. 4672-4679.

Research output: Contribution to journalArticle

Crittenden, Christopher M. ; Escobar, Edwin E. ; Williams, Peggy E. ; Sanders, James D. ; Brodbelt, Jennifer. / Characterization of Antigenic Oligosaccharides from Gram-Negative Bacteria via Activated Electron Photodetachment Mass Spectrometry. In: Analytical Chemistry. 2019 ; Vol. 91, No. 7. pp. 4672-4679.
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