CE‐MSⁿ of complex pectin‐derived oligomers

Abstract

As pectin molecules are too large and heterogeneous to analyze as a whole, the polymer is usually degraded to smaller oligomers, which are often analyzed by high-performance anion exchange chromatography (HPAEC). However, the high salt concentration necessary to elute pectin oligomers by HPAEC is incompatible with online mass detection. To overcome such a disadvantage, a CE-IT-MS system was set up to further elucidate the fine structure of charged oligosaccharides. An effective separation of differently substituted galacturonic acid containing oligomers was obtained by low-pH CE-LIF analysis. By adapting the buffer and capillary online MS detection was enabled. Moreover, with MS/MS it was possible to localize sugar residues' substitutions. With this combined CE-MS approach LIF electropherograms of xylogalacturonan and rhamnogalacturonan I digests could be annotated. The method was further exemplified by a complex oligomer mixture of acid hydrolyzed apple pectin, which was separated and characterized by CE-MSn. Oligomers present in low amounts could be localized by their corresponding m/z, as was demonstrated by selected mass range representation.

Biosynthesis of Pectin

“…Even a model suggesting that HG and its substituted variants are side chains of RGI was proposed (Vincken et al, 2003). However, the discovery of RGI backbone oligomers with HG and XGA as nonreducing end extensions suggests otherwise (Nakamura et al, 2002;Coenen et al, 2008).…”

CE‐LIF‐MSn profiling of oligosaccharides in human milk and feces of breast‐fed babies

“…On-line LIF electropherograms showed some peak overlap, which was not the case for the MS base peak chromatograms, due to ongoing electrophoretic separation between LIF and MS detector. The time difference between on-line LIF peak detection and MS detection was 5 min, which is small compared with Z10 min reported in earlier studies [27,38]. A sheath-flow interface was used for transferring liquid from the CE capillary outlet to the MS inlet.…”

Mass Spectrometry for Characterizing Plant Cell Wall Polysaccharides

“…The use of powerful mass analyzers with MS/MS (triple quadrupole, TOF/TOF) or even MS n (ion trap, IT) capabilities in conjunction with reverse-phase, normal phase (NP), porous graphitized carbon, size exclusion, ion exchange, or high-performance anion-exchange, liquid chromatographic (LC) or capillary electrophoretic separation methods has increased the role of mass spectrometry for oligosaccharide structural characterization (Schols et al, 1994; Deery et al, 2001; Kabel et al, 2001; Mazumder et al, 2005; Hilz et al, 2006; Coenen et al, 2008). The main function of these coupling techniques is reduction of complexity by separation of isobaric structures that are not resolved by MS.…”

“…Introduction of a permanent charge (e.g., quartenary ammonium groups) or an ionizable function (amino or carboxy group) not only increases sensitivity and often attaches a chromophore group to the molecule but also fixes the charge state at one side of the molecule (Harvey, 2000; Gouw et al, 2002; Coenen et al, 2008). This greatly enhances the intensities of ions containing the charged label and supports structure confirmation.…”