Collision-induced dissociation of sodiated glucose and identification of anomeric configuration

Abstract

Collision-induced dissociation (CID) of sodiated glucose was investigated using electronic structure calculations and resonance excitation in a low-pressure linear ion trap. The major dissociation channels in addition to desodiation are dehydration and CHO elimination reactions which the barrier heights are near to or lower than the sodiation energy of glucose. Dehydration reaction involves the transfer of the H atom from the O2 atom to the O1 atom, followed by the cleavage of the C1-O1 bond. Notably, α-glucose has a dehydration barrier lower than that of β-glucose. This difference results in the larger branching ratio of dehydration reactions involving α-glucose, which provides a simple and fast method for identifying the anomeric configurations of glucose. The CHO elimination starts from the H atom transfer from the O1 atom to the O0 atom, followed by the cleavage of the C1-O0 bond. These results were further confirmed by experimental study using O-isotope-labeled compounds. Both the experimental data and theoretical calculations suggest that the dehydration reaction and cross-ring dissociation of sodiated carbohydrates mainly occur at the reducing end during low-energy CID.

Does low‐energy collision‐induced dissociation of lithiated and sodiated carbohydrates always occur at anomeric carbon of the reducing end?

“…CID of sodiated glucose has been investigated extensively by theoretical calculations in a previous study . Calculations were focused on the search for the lowest dissociation barriers of various dissociation channels.…”

“…However, the barrier heights of these isomerizations are all very low. Detailed barrier heights for isomerizations of sodiated glucose were reported in a previous study …”

Automatic Full Glycan Structural Determination through Logically Derived Sequence Tandem Mass Spectrometry

“…A major difference between the CID spectra of two anomers of a given hexose (e.g., Figure B and C for α‐ and β‐glucose, respectively) is the relative intensity of ion m / z 169, which represents H 2 O elimination. High‐level quantum chemistry calculations have revealed that the water elimination barriers of the O1 and O2 atoms in the cis configuration of the sodium adduct were substantially smaller than that in the trans configuration . We found that lithium adducts had similar properties.…”

“…However, information on the anomeric configuration and monosaccharide constituents was not available. In this study, we extended the use of cross‐ring fragments to identify the linkage positions and anomeric configurations of disaccharides containing glucose, galactose, mannose, GalNAc, and GlcNAc based on an understanding of the dissociation mechanism . The third one is the capability to dissociate selective chemical bonds and generate the chosen mono‐ or disaccharide for subsequent structural determination.…”

Proposal for a chemically consistent way to annotate ions arising from the analysis of reference compounds under ESI conditions: A prerequisite to proper mass spectral database constitution in metabolomics

“…In positive ionization mode, adduct ions formed with cations may have different origins and may result from: the protonation of a basic site of an entity already existing as a salt; the charge solvation of a metal cation by the lone‐pair(s) of heteroatom(s) of either (A) a molecule or (B) a salt. Representative examples of such adduct ions possibly formed with glucose and sodium cations are depicted in Figure as well as the corresponding proposed annotation.…”