Collision-Induced Dissociation of Cellobiose and Maltose

Abstract

Structure determination is a longstanding bottleneck of carbohydrate research. Tandem mass spectrometry (MS/MS) is one of the most widely used methods for carbohydrate structure determination. However, the effectiveness of MS/MS depends on how the precursor structures are derived from the observed fragments. Understanding the dissociation mechanisms is crucial for MS/MS-based structure determination. Herein, we investigate the collision-induced dissociation mechanism of β-cellobiose and β-maltose sodium adducts using quantum chemical calculations and experimental measurements. Four dissociation channels are studied. Dehydration mainly occurs through the transfer of an H atom to O1 of the sugar at the reducing end, followed by a C1−O1 bond cleavage; cross-ring dissociation starts with a ring-opening reaction, which occurs through the transfer of an H atom from O1 to O5 of the sugar at the reducing end. These two dissociation channels are analogous to that of glucose monosaccharide. The third channel, generation of B 1 and Y 1 ions, occurs through the transfer of an H atom from O3 (cellobiose) or O2 (maltose) to O1 of the sugar at the nonreducing end, followed by a glycosidic bond cleavage. The fourth channel, C 1 −Z 1 fragmentation, has two mechanisms: (1) the transfer of an H atom from O3 or O2 to O4 of the sugar at the reducing end to generate C ions in the ring form and (2) the transfer of an H atom from O3 of the sugar at the reducing end to O5 of the sugar at the nonreducing end to produce C ions in the linear form. The results of calculations are supported by experimental collision-induced dissociation spectral measurements.

Electrospray ionization in‐source decay of N‐glycans and the effects on N‐glycan structural identification

“…[43][44][45] The cleavage of glycosidic bond to generate C/Z ions has a high barrier, and the corresponding ion intensities in CID spectra are usually smaller than that of B/Y ions. 42 spectrum shows that the co-fragment (N-glycan without sialic acid) remains as the doubly charged ion (m/z 906). It is likely the sodiated energy of sialic acid is not large enough to compete with its co-fragment for sodium ion during the dissociation process, and both sodium ions remain on the same fragment (i.e., on N-glycan without sialic acid).…”

“…Most of the precursor ions are dissociated by CID through the dissociation channels that have low barriers. These low‐barrier channels include the elimination of sialic acid, fucose, mannose, or GlcNAc through the cleavage of one glycosidic bond to generate B/Y ions, 42 dehydration at the reducing end to generate B ion, and cross‐ring dissociation at the reducing end to generate A ions 43–45 . The cleavage of glycosidic bond to generate C/Z ions has a high barrier, and the corresponding ion intensities in CID spectra are usually smaller than that of B/Y ions 42 .…”

“…These low‐barrier channels include the elimination of sialic acid, fucose, mannose, or GlcNAc through the cleavage of one glycosidic bond to generate B/Y ions, 42 dehydration at the reducing end to generate B ion, and cross‐ring dissociation at the reducing end to generate A ions 43–45 . The cleavage of glycosidic bond to generate C/Z ions has a high barrier, and the corresponding ion intensities in CID spectra are usually smaller than that of B/Y ions 42 . Our results show that the energy transfer from the heated capillary is involved in the ESI in‐source decay of most fragments, but the dissociation patterns of ESI in‐source decay are slightly different from those of CID, indicating that the mechanism of ESI in‐source decay is not completely the same as that of CID.…”

The Good, the Bad, and the Ugly Memories of Carbohydrate Fragments in Collision-Induced Dissociation

“…Dehydration and cross-ring dissociation at the reducing end and glycosidic bond cleavage to generate B or Y ions endothermic reactions with small heat of reaction as well as and low dissociation barrier height. By contrast, glycosidic bond cleavage to generate C or Z ions are endothermic reaction with small heat of reaction but large dissociation barrier heights . Here, B, C, Y, and Z ions are denoted according to Domon and Costello’s nomenclature .…”

“…By contrast, glycosidic bond cleavage to generate C or Z ions are endothermic reaction with small heat of reaction but large dissociation barrier heights. 42 Here, B, C, Y, and Z ions are denoted according to Domon and Costello's nomenclature. 35 The CID sequence in Figure 4h was designed to generate the C ion m/z 527, containing three hexoses at the nonreducing end, from ion m/z 877 by breaking glycosidic bond between sugars 3 and 4 (pathway I in Figure 4h).…”