Structural Characterization of Isomeric Oligogalacturonan
Mixtures Using Ultrahigh-Performance Liquid Chromatography-Charge
Transfer Dissociation Mass Spectrometry
posted on 2021-01-26, 19:03authored byPraneeth
M. Mendis, Zachary J. Sasiene, David Ropartz, Hélène Rogniaux, Glen P. Jackson
Pectins are natural polysaccharides
made from galacturonic acid
residues, and they are widely used as an excipient in food and pharmaceutical
industries. The degree of methyl-esterification, the monomeric composition,
and the linkage pattern are all important factors that influence the
physical and chemical properties of pectins, such as the solubility.
This work focuses on the successful online coupling of charge transfer
dissociation–mass spectrometry (CTD-MS) with ultrahigh-performance
liquid chromatography (UHPLC) to differentiate isomers of oligogalacturonans
derived from citrus pectins. This work employed CTD fragmentation
of the pectin mixtures in data-dependent acquisition mode. Compared
to the UHPLC with collision-induced dissociation mass spectrometry
(UHPLC-CID-MS), UHPLC-CTD-MS yielded fewer ambiguous ions and more
structurally informative results. The developed UHPLC-CTD-MS method
resulted in abundant cross-ring cleavagesand especially 1,4Xn, 1,5Xn, and 2,4Xn ionswhich helped to identify most of the isomers. The Gal
A isomers differed only in the methyl group position along the galacturonic
acid backbone. The combination of CTD in real time with UHPLC provides
a new tool for the structural characterization of complex mixtures
of oligogalacturonans and potentially other classes of oligosaccharides.