Electrospray tandem mass spectrometry of underivatised acetylated xylo‐oligosaccharides

Abstract

Acetylated neutral (Xyl(n)Ac(m)) and acidic xylo-oligosaccharides (Xyl(n)Ac(m)MeGlcA, and Xyl(n)Ac(m)MeGlcAHex) obtained by partial acid hydrolysis of Eucalyptus globulus wood glucuronoxylans and fractionated by preparative ligand exchange/size-exclusion chromatography were identified by electrospray ionisation mass spectrometry (ESI-MS). Low molecular weight acetylated xylo-oligosaccharides were studied by ESI-tandem mass spectrometry (MS/MS). All the acetylated xylo-oligosaccharides showed an abundant ion due to the neutral loss of 60 Da (CH(3)CO(2)H) in the MS/MS spectra. The presence of diacetylated xylo-oligosaccharides was confirmed by the ions formed by loss of two molecules of acetic acid. Furthermore, characteristic [Xyl(res)Ac(2)+Na](+) and [XylAc(2)+Na](+) ions, and ions due to loss of XylAc(2), indicate that both acetyl groups are located in the same Xyl residue. On the other hand, losses of Xyl(res)Ac and XylAc are also observed as well as [Xyl(res)Ac+Na](+) and [XylAc+Na](+) , indicating the location of both acetyl groups in different Xyl residues, in some cases even in adjacent xyloses. The MS/MS spectra of triacetylated xylo-oligosaccharides were complex due to the presence of different isobaric xylo-oligosaccharides containing the acetyl groups at different locations in the xylo-oligosaccharide backbone. In the MS/MS spectra of acidic xylo-oligosaccharides, the ion at m/z 387, [Xyl(res)AcMeGlcA+Na](+), indicates that the acetyl groups are preferentially linked to Xyl substituted with MeGlcA. However, acidic xylo-oligosaccharides with the acetyl and 4-O-methylglucuronic acid groups in different Xyl residues were also identified. In neutral and in acidic xylo-oligosaccharides several possible locations of the acetyl groups were identified, namely at terminal positions. In summary, ESI-MS/MS is shown to be a powerful tool for the characterisation of acetylated patterns in complex mixtures of oligosaccharides.

Neutral and acidic products derived from hydroxyl radical-induced oxidation of arabinotriose assessed by electrospray ionisation mass spectrometry

“…Figure A shows the LEX/SEC chromatograms of the stock solution of Ara 3 (4 mg/ml) and the reaction mixture (Ara 3 /Fe 2+ /H 2 O 2 ). According to results of previous studies, the peak with the lowest elution time (10–12 min; F1) in the chromatogram of the reaction mixture was assigned to the acidic products of Ara 3 . Also, considering the elution time of the Ara 3 (maximum of the peak at 17 min), the fraction eluted at 16–18 min was mainly assigned to neutral trisaccharides.…”

Isolation of inulin‐type oligosaccharides from Chinese traditional medicine: Morinda officinalis How and their characterization using ESI‐MS/MS

“…4. The oligosaccharides cleavage in MS/MS spectra has been discussed in previous literatures [19][20][21]. The fragment ions of oligosaccharides mainly result from glycosidic cleavages between two sugar residues and cross-ring cleavages of two bonds within the sugar ring.…”

Xylooligosaccharides (XOS) as an Emerging Prebiotic: Microbial Synthesis, Utilization, Structural Characterization, Bioactive Properties, and Applications

“…The analysis of oligosaccharides released from xylans has been mainly done by NMR, and also by mass spectrometry using MALDI‐MS (Huisman and others 2000; Deery and others 2001; Jacobs and others 2001; Kabel and others 2002a; Reis and others 2003a) and electrospray tandem mass spectrometry (ESI‐MS) (Reis and others 2002, 2003b). Recently, positive tandem mass spectrometry using ESI was proposed for the characterization of underivatized neutral and acidic XOS formed by partial acid hydrolysis (Reis and others 2002, 2003b, 2005).…”