Mechanistic Study into Free Radical-Activated Glycan Dissociations through Isotope-Labeled Cellobioses.

Inspired by the electron-activated dissociation technique, the most potent tool for glycan characterization, we recently developed free radical reagents for glycan structural elucidation. However, the underlying mechanisms of free radical-induced glycan dissociation remain unclear and, therefore, hinder the rational optimization of the free radical reagents and the interpretation of tandem mass spectra, especially the accurate assignment of the relatively low-abundant but information-rich ions. In this work, we selectively incorporate the C and/or O isotopes into cellobiose to study the mechanisms for free radical-induced dissociation of glycans.

Free-Radical-Mediated Glycan Isomer Differentiation.

The inherent structural complexity and diversity of glycans pose a major analytical challenge to their structural analysis. Radical chemistry has gained considerable momentum in the field of mass spectrometric biomolecule analysis, including proteomics, glycomics, and lipidomics. Herein, seven isomeric disaccharides and two isomeric tetrasaccharides with subtle structural differences are distinguished rapidly and accurately via one-step radical-induced dissociation.