Structural characterisation by both positive- and negative-ion electrospray mass spectrometry of partially methyl-esterified oligogalacturonides purified by semi-preparative high-performance anion-exchange chromatography.
The off-line coupling of high-performance anion-exchange chromatography (HPAEC) to electrospray ionisation/ion trap mass spectrometry (ESI-ITMS) is described. The Dionex carbohydrate membrane desalter (CMD) 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 indirect coupling with ESI-ITMS. This paper provides some interesting features of positive- and negative-ion multistage tandem mass spectrometry (MS(n)) 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 mass spectrometric fragmentation routes are also described. The positive-ion mode gave more complex spectra but was as informative as the negative-ion mode. ESI-ITMS was revealed to be, as previously reported from direct use on an unseparated enzymatic digest, a powerful sequencing technique for the determination of linkage type and the methyl ester distribution of partially methyl-esterified oligogalacturonides. Moreover, unlike matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF MS), it gives valuable information on the elution behaviour of these oligomers in relation to their structure, namely the HPAEC co-elution of isomeric structures.
Institut National de la Recherche Agronomique, Unité de Recherche sur les Polysaccharides, leurs Organisations et leurs Interactions (URPOI), rue de la Géraudière, BP 71627, 44316 Nantes, France. quemener@nantes.inra.fr
Bernard
B
Quéméner
Cédric
C
Désiré
Marc
M
Lahaye
Laurent
L
Debrauwer
Luc
L
Negroni
D002852:Chromatography, Ion Exchange / Q000379:methods*; D004952:Esters / Q000737:chemistry; D007536:Isomerism; D008745:Methylation; D015394:Molecular Structure; D009844:Oligosaccharides / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D004952:Esters; D009844:Oligosaccharides; C412763:oligogalacturonic acid