Populations of metal-glycan structures influence MS fragmentation patterns.

The structures and collision-induced dissociation (CID) fragmentation patterns of the permethylated glycan Man5GlcNAc2 are investigated by a combination of hybrid ion mobility spectrometry (IMS), mass spectrometry (MS), and MS/MS techniques. IMS analysis of eight metal-adducted glycans ([Man5GlcNAc2 + M](2+), where M = Mn, Fe, Co, Ni, Cu, Mg, Ca, and Ba) shows distinct conformer patterns. These conformers appear to arise from individual metals binding at different sites on the glycan. Fragmentation studies suggest that these different binding sites influence the CID fragmentation patterns. This paper describes a series of separation, activation, and fragmentation studies that assess which fragments arise from each of the different gas-phase conformer states. Comparison of the glycan distributions formed under gentle ionization conditions with those obtained after activation of the gas-phase ions suggests that these conformer binding states also appear to exist in solution.