This study demonstrates that neutral gas activated carbohydrate ions can be disassociated in a step-wise, structurally dependent manner to yield regio-specific linkage fragments. Such ions can be captured, documented and shared, retaining all aspects of structure for sequence understanding. Extensive studies for over two decades have shown the fidelity of disassembly with a large cross selection of synthetic and natural carbohydrate samples. Identical results have also been observed with abbreviated steps in triple quadrupoles and exacting results in both linear and quadrupolar ion traps, supporting the concept that following activation, disassembly is an independent physiochemical process controlled only by its inherent structure. Moreover, three additional facts complement this approach as an effective sequence technology; 1.) a loss of native background ions with early MS<b><sup>n</sup></b> steps, allows commensurate sample ion amplification; 2.) double and triple charging significantly extends mass range; and, 3.) incrementing steps of disassembly occur at higher energies that must be shared with smaller oscillator number, a feature that provides greater structural detail in core areas of stability. This latter feature is predicted by the quasi-equilibrium theory, (RRKM). With support from these basic physiochemical facts, we turned our attention to challenging stereo-isomers, as known in the equatorial-axial pyran isomers, (the C4 Gal/Glc, GlcN/GalN and the C2 Glc/Man monomers). Synthetic regio-specific disaccharide samples that included these specific stereoisomers did produce differential spectra upon disassembly, completing a spatial regio-specific analysis. Since synthesis is revered as a proof of structure, so in a reverse sense, disassembled products allow an opportunity to document precursors in defining sequence. Equally important is the opportunity to challenge all products by spectral documentation. Such searchable files and documentation would greatly facilitate collaborative research, a fundamental component long missing in glycosylation studies.

Glycan spatial sequencing with regio-specific spectral documentation

255th National Meeting (2018)

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