Fragmentation of negative ions from carbohydrates: Part 2. Fragmentation of high-mannose N-linked glycans

DJ Harvey - Journal of the American Society for Mass Spectrometry, 2005 - Springer
DJ Harvey
Journal of the American Society for Mass Spectrometry, 2005Springer
Abstract [M+ NO 3]− And [M+(NO 3) 2] 2− ions were produced by electrospray from neutral
high-mannose ([Man] 5–9 [GlcNAc] 2,[Glc] 1–3 [Man] 4–9 [GlcNAc] 2) N-linked glycans and
their 2-aminobenzamide derivatives sprayed from methanol: water containing ammonium
nitrate. Low energy collision-induced decomposition (CID) spectra of both types of ions were
almost identical and dominated by cross-ring and C-type fragments, unlike the
corresponding spectra of the positive ions that contained mainly B-and Y-type glycosidic …
Abstract
[M +NO3] And [M +(NO3)2]2− ions were produced by electrospray from neutral high-mannose ([Man]5–9[GlcNAc]2, [Glc]1–3[Man]4–9[GlcNAc]2) N-linked glycans and their 2-aminobenzamide derivatives sprayed from methanol:water containing ammonium nitrate. Low energy collision-induced decomposition (CID) spectra of both types of ions were almost identical and dominated by cross-ring and C-type fragments, unlike the corresponding spectra of the positive ions that contained mainly B- and Y-type glycosidic fragments. This behavior could be rationalized by an initial proton abstraction from various hydroxy groups by the initially-formed anionic adduct. These negative ion spectra were more informative than the corresponding positive ion spectra and contained prominent ions that were diagnostic of structural features such as the composition of individual antennas that were not easily obtainable by other means. C-ions defined the sequence of the constituent monosaccharide residues. Detailed fragmentation mechanisms are proposed to account for many of the diagnostic ions.
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