Mass spectrometry (MS) is a powerful tool for the biosynthetic studies of plant cell walls. The method requires only minute amount of sample and is capable of elucidating the structural differences of heterogenic wall polysaccharide derived fragments (oligosaccharides). O-acetylglucuronoxylans (AcGX) are abundantly present in the secondary cell of flowering plants. The AcGX backbone is formed by beta-D-xylopyranosyl residues, some of which carry alpha-(4-O-methyl)glucopyranosyluronic acid and acetyl residues at the 2-O/and 3-O positions. Enzymatic hydrolysis releasing oligosaccharide directly from the plant material for the MS analysis was exploited to study O-acetylation of glucuronoxylan in different hardwood species and of Arabidopsis thaliana xylan biosynthesis mutants. The released oligosaccharides were further analyzed by the atmospheric pressured-matrix assisted laser desorption ionization-ion trap mass spectrometry (AP-MALDI-ITMS). The AP-MALDI-ITMS offers the advantage to analyze the mass (fingerprint spectrum) and structure (MS/MS analysis) of complex oligosaccharides in one system. The % intensities of the mass peaks were compared and analyzed further by principal component analysis (PCA) to identify the Arabidopsis mutants with altered O-acetylation in glucuronoxylan. The MS/MS analysis also revealed information on the spatial distribution on O-acetyl residues. Moreover, a novel pentose branching in Arabidopsis glucuronoxylan was identified. Endoxylanase hydrolysis followed by AP-MALDI-ITMS detection was shown to be a selective and sensitive tool for studying the structural details of O-acetylglucuronoxylans in a semi-high throughput manner. The method is well suited to analyze large numbers of samples.

Mass spectrometry analysis of structural details in O-acetylglucuronoxylans

249th National Meeting (2015)

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Mass spectrometry analysis of structural details in O-acetylglucuronoxylans<br />