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Eur. J. Mass Spectrom. DOI: 10.1255/ejms.526 |
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Structural characterization by both positive and negative electrospray mass spectrometry of partially methyl-esterified oligogalacturonides puriefied by semi-preparative high performance anion exchange chromatography | ||
Bernard Quéméner, Cédric Désiré and Marc Lahaye |
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ABSTRACT: | ||
The off-line coupling of high performance anion exchange chromatography (HPAEC) to electrospray ionization/ion trap mass spectrometry (ESI-ITMS) is described. The Dionex Carbohydrate Membrane Desalter (CDM) has been assessed as an on-line chromatographic desalting system to remove the high sodium concentration necessary for the HPAEC separation of partially methyl-esterified oligogalacturonides. The developed HPAEC configuration proved to be suitable for the indirect coupling with ESI-ITMS. This paper provides some interesting features of positive and negative MSn analysis of these acidic oligosaccharides. The spectra acquired in both negative- and positive-ion modes show characteristic fragment ions resulting from glycosidic bond and cross-ring cleavages. Some new MS fragmentation routes are also described. The positive-ion mode gave more complex spectra but was as informative as the negative one. ESI-ITMS revealed to be, as previously reported directly on non-separated enzymatic digest, a powerful sequencing technique for the determination of the linkage type and the methylester distribution of partially methyl-esterified oligogalacturonides. Moreover, contrary to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, it gives valuable information on the elution behavior of these oligomers in relation to their structure, namely the HPAEC coelution of isomeric structures | ||
Keywords: pectins, endogalacturonase, partially-esterified oligogalacturonides, structural characterization, HPAEC, ESI-ITMS |
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