Structure Determination of Large Isomeric Oligosaccharides of Natural Origin through Multipass and Multistage Cyclic Traveling-Wave Ion Mobility Mass Spectrometry

Abstract

Carbohydrate isomers with identical atomic composition cannot be distinguished by mass spectrometry. By separating the ions according to their conformation in the gas phase, ion mobility (IM) coupled to mass spectrometry is an attractive approach to overcome this issue and extend the limits of mass spectrometry in structural glycosciences. Recent technological developments have significantly increased the resolving power of ion mobility separators. One such instrument features a cyclic traveling-wave IM separator integrated in a quadrupole/time-of-flight mass spectrometer. This system allows for multipass ion separations and for pre-, intra-, and post-IM fragmentation.In the present study, we utilize this system to explore a complex mixture of oligoporphyrans derived from the enzymatic digestion of the cell wall of the red alga P. umbilicalis. We are able to deduce their complete structure using IM arrival times and the m/z of specific fragments. This approach was successfully applied for sequencing of oligoporphyrans of up to 1500 Da and included the positioning of the methyl ether and sulfate groups. The structures defined in this study by IM-MS/MS agree with those found in the past but use much more time-consuming analytical approaches. This study also revealed some so far undescribed structures, present at very low abundance. In addition, the results made it possible to compare the abundance of the different isomers released by the enzyme and to draw further conclusions on the specificity of β-porphyranase and more particularly on its accommodation tolerance of anhydro-bridges in subsites. Finally, a separation of two isomers with very similar mobility was obtained after 58 passes around the cIM, with an estimated resolving power of 920 for these triply charged species, confirming the structures attributed to these two isomers.

Application of a novel cyclic ion mobility‐mass spectrometer to the analysis of synthetic polymers: A preliminary evaluation

“…This arrangement is capable of manipulating the ions to effect injection and ejection into and out of the ion mobility separator, enabling the use of complex ion mobility sequences. A full description of cyclic sequence methods, and how they are developed, is given elsewhere; in addition, full details of the timings used for the methods employed within this work are presented in Table S1 (supporting information). These sequences were developed in a stepwise manner while observing the arrival times of key ions of interest to track the number of passes of the cyclic device completed by the ions of interest.…”

“…Early work on this concept was carried out by Merenbloom and co‐workers, while the commercial realisation of this approach has recently been completed by Giles and co‐workers to deliver an integrated cyclic ion mobility‐mass spectrometry (cIM‐MS) system. The most obvious technical advancement from this type of instrument is the potential for improved IM resolution; however, novel developments in ion manipulation provide further scope for new experimental approaches and improvements to current IM acquisitions . The work presented here explores both the effects of increased IM resolution and the possibilities for new experimental designs for synthetic polymer analysis.…”

Discovery and Biotechnological Exploitation of Glycoside-Phosphorylases

“…When no standards are available, highly resolutive MS-MS can be used to determine the linkage position. Recent methods, such as ion-mobility based separation, offer exquisite carbohydrate separation, even for isomers co-eluted by other separation techniques [ 272 ]. Associated with very sensitive and specific tandem MS methods, (complex) carbohydrate structure can now be completely elucidated [ 272 , 273 ].…”

“…Recent methods, such as ion-mobility based separation, offer exquisite carbohydrate separation, even for isomers co-eluted by other separation techniques [ 272 ]. Associated with very sensitive and specific tandem MS methods, (complex) carbohydrate structure can now be completely elucidated [ 272 , 273 ]. This analysis only requires 1 µg of carbohydrate, directly from reactional mixtures.…”

Synthesis of an Exhaustive Library of Naturally Occurring Galf-Manp and Galp-Manp Disaccharides. Toward Fingerprinting According to Ring Size by Advanced Mass Spectrometry-Based IM-MS and IRMPD

“…As shown in the literature, this level of IM resolution allows the gas phase separation of isomers and conformers prior to their mass measurement. [56][57][58] After massselection of each disaccharide using a quadrupole filter, we recorded the set of gas-phase conformations for each ion, translated into CCS distributions (CCSDs). As shown in figure 2 for the eight FP and PP disaccharides, a single disaccharide can give a single conformer or multiple ones with different CCSs, intensities, and peak shapes.…”