The structural elucidation of bacterial capsular polysaccharides using laser desorption ionisation fourier transform ion cyclotron resonance spectroscopy

Coordination of Alkali Metals to Oligosaccharides Dictates Fragmentation Behavior in Matrix Assisted Laser Desorption Ionization/Fourier Transform Mass Spectrometry

“…Laser desorption, with and without, matrix has been more recently developed but has been used already with great success to analyze carbohydrate structures. Extensive fragementation is observed without matrix providing numerous structurally important fragment ions. − Laser desorption without matrix (LD) is unfortunately also limited by its relatively poor detection limits. Matrix assisted laser desorption ionization (MALDI) mass spectrometry is, in contrast, a highly sensitive method but often lacks the high degree of fragmentation necessary for the structural elucidation .…”

Structural and reaction assignments for some common polysaccharides using laser desorption ionization Fourier transform ion cyclotron resonance spectroscopy

“…In our prior (13) oligosaccharide work, we noted that the most prominent ring cleavage, shown in Figure 2, occurs between the ring oxygen and C-l, and between C-2 and C-3, to give a two-carbon unsaturated fragment containing C-l and C-2. This unsaturated moiety is attached via a glycosidic oxygen atom to a fragment that contains the reducing end of oligomer (13). This type of fragmentation route is designated as the M-type fragmentation in Figures 2 and 3 C 24…”

“…This is the case for all of the Coates-Wilkins polysaccharides (12). For other cases, for example, polymers containing some deoxyhexopyranose residues in the main chain, the two paths can be distinguished (13).…”

“…Ionization techniques such as FAB induce fragmentation at the glycosidic bonds of oligosaccharides (5,7). LDI-FT-ICR spectra of carbohydrates also show glycosidic bond fragmentation (13). Following Kochetkov's convention, we label this glycosidic bond cleavage of the saccharide chain the L-type fragmentation.…”

Photodissociation of laser-desorbed ions as a structure determination tool

“…It is a relatively soft ionization technique and usually yields high abundances of molecular ions or cation-attached molecular ions, allowing facile determinations of molecular weight. Laser desorption also results in fragment ions, depending upon the nature of the sample (6,7). However, more fragmentation often is required in order to allow inference of molecular structure.…”