Structural resolution of carbohydrate positional and structural isomers based on gas-phase ion mobility-mass spectrometry

Abstract

This report describes the rapid characterization of positional and structural carbohydrate isomers based on structural separations provided by ion mobility-mass spectrometry (IM-MS). Many of the diseases associated with glycoprotein variation can be more effectively treated with earlier detection substantiating the need for high-throughput methodologies for glycan characterization. This remains particularly difficult due to heterogeneity, branching, and large size of carbohydrate moieties which creates the potential for numerous isobaric positional and structural isomers that are difficult to characterize using conventional MS methods. IM-MS provides rapid (μs to ms) structural separations by IM and subsequent identification by MS which presents a means for characterization of positional and structural carbohydrate isomers. To chart the structural variation observed in IM-MS, the ion-neutral collision cross sections for over 300 carbohydrates are reported. This diversity can also be varied through the utility of using different alkali metals to tune separation selectivity via alkali metal-carbohydrate coordination. Furthermore, the advantages of combining either pre- and/or post-IM fragmentation prior to MS analysis is demonstrated for enhanced confidence in carbohydrate identification.

Adduct-ion formation in trapped ion mobility spectrometry as a potential tool for studying molecular structures and conformations

“…A common approach to separate isomers, which exhibit similar collision cross section (CCS (Å 2 )), is the use of mono-and divalent cations, which form distinguishable adduct complexes with the target analytes, and has led to successful separations of isomeric carbohydrates, lipids, and peptides [8][9][10][11][12][13]. The improved resolution was due to mobility shifts in one of the isomeric forms as a result of conformational changes induced by cation adduct formation.…”

Biologically-Inspired Peptide Reagents for Enhancing IMS-MS Analysis of Carbohydrates

“…The combination of collision induced dissociation (CID) with electron transfer dissociation (ETD) is making it possible to determine peptide sequences as well as glycan positions and structures [3]. Recently, ion mobility spectrometry (IMS) [6] has emerged as a means of separating isomers prior to MS analysis [7][8][9][10][11][12][13][14][15][16]. Because IMS separates ions based on their shapes, it also offers information that is complementary to MS analysis.…”

“…Because saccharidebased analytes do not typically protonate favorably, electrospray ionization (ESI) [20] typically involves salt-containing solutions to form metal cation adducts. Sodium salts are most typically used, although other alkali metals [16] and some transition metals [12] have been investigated.…”

Direct Infusion Electrospray Ionization – Ion Mobility – High Resolution Mass Spectrometry (DIESI-IM-HRMS) for Rapid Characterization of Potential Bioprocess Streams

“…A few analytes common to many biomass samples have been independently investigated with IM-MS (often using commercially available standards), including acetic acid [21] and several carbohydrates [21,[25][26][27][37][38][39], such as 5-and 6-carbon mono/oligosaccharides. However, in almost all of these studies, only positive ions have been analyzed, which is contrary to established mass spectrometry protocols for biomass analysis [5,14].…”

“…IM-MS has been applied as an effective tool for complex sample analysis in several fields, including proteomics [15][16][17], petroleomics [18][19][20], and metabolomics [21][22][23], and has the ability to separate ions based on differences in chemical class [24][25][26][27] and to distinguish between various molecular conformations and geometries [16,[18][19][20]28]. IM-MS has also been utilized in small molecule analyses, including separation of pharmaceutical drug formulations [29,30], chiral amino acid enantiomers [31], alkaloid stereoisomers [32], trace analysis of drugs [33], and screening for chemical warfare agents [34][35][36].…”