Development of mass spectrometric glycan characterization tags using acid‐base chemistry and/or free radical chemistry.

Despite recent advances in glycomics, glycan characterization still remains an analytical challenge. Accordingly, numerous glycan‐tagging reagents with different chemistries were developed, including those involving acid‐base chemistry and/or free radical chemistry. Acid‐base chemistry excels at dissociating glycans into their constituent components in a systematic and predictable manner to generate cleavages at glycosidic bonds. Glycans are also highly susceptible to depolymerization by free radical processes, which is supported by results observed from electron‐activated dissociation techniques. Therefore, the free radical activated glycan sequencing (FRAGS) reagent was developed so as to possess the characteristics of both acid‐base and free radical chemistry, thus generating information‐rich glycosidic bond and cross‐ring cleavages. Alternatively, the free radical processes can be induced via photodissociation of the specific carbon‐iodine bond which gives birth to similar fragmentation patterns as the FRAGS reagent. Furthermore, the methylated‐FRAGS (Me‐FRAGS) reagent was developed to eliminate glycan rearrangements by way of a fixed charged as opposed to a labile proton, which would otherwise yield additional, yet unpredictable, fragmentations including internal residue losses or multiple external residue losses. Lastly, to further enhance glycan enrichment and characterization, solid‐support FRAGS was developed. [ABSTRACT FROM AUTHOR]