Eradicating mass spectrometric glycan rearrangement by utilizing free radicals

Nikunj Desai, Daniel A. Thomas, Jungeun Lee, Jinshan Gao, J. L. Beauchamp

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Mass spectrometric glycan rearrangement is problematic because it provides misleading structural information. Here we report on a new reagent, a methylated free radical activated glycan sequencing reagent (Me-FRAGS), which combines a free radical precursor with a methylated pyridine moiety that can be coupled to the reducing terminus of glycans. The collisional activation of Me-FRAGS-derivatized glycans generates a nascent free radical that concurrently induces abundant glycosidic bond and cross-ring cleavage without the need for subsequent activation. The product ions resulting from glycan rearrangement, including internal residue loss and multiple external residue losses, are precluded. Glycan structures can be easily assembled and visualized using a radical driven glycan deconstruction diagram (R-DECON diagram). The presence and location of N-acetylated saccharide units and branch sites can be identified from the characteristic dissociation patterns observed only at these locations. The mechanisms of dissociation are investigated and discussed. This Me-FRAGS based mass spectrometric approach creates a new blueprint for glycan structure analysis.

Original languageEnglish
Pages (from-to)5390-5397
Number of pages8
JournalChemical Science
Issue number8
StatePublished - 2016


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