Application of nano-probe NMR for structure determination of low nanomole amounts of arabinoxylan oligosaccharides fractionated by analytical HPAEC-PAD

• Published in: Carbohydrate research 2000-09, Vol.328 (3), p.375-382
• Main Authors: Broberg, Anders, Thomsen, Karl Kristian, Duus, Jens Ø.
• Format: Article
• Language: English
• Subjects: Arabinoxylan; Barley; Carbohydrate Conformation; Carbohydrate Sequence; Cell Wall - chemistry; Chromatography, Ion Exchange - methods; Hordeum - chemistry; HPAEC-PAD; Magnetic Resonance Spectroscopy - methods; MALDI-TOF MS; Molecular Sequence Data; Nano-probe NMR; Oligosaccharide; Oligosaccharides - chemistry; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Structure; Xylans - chemistry
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(00)00108-7

A methodology for NMR analysis of low nanomole amounts of oligosaccharides fractionated by analytical HPAEC is presented. Arabinoxylan derived oligosaccharides purified by HPAEC-PAD on an analytical column, by single injections, were analyzed with nano-probe NMR and MALDI-TOF MS to provide full structural assignment. The NMR data were obtained with a 500 MHz NMR spectrometer equipped with a 1H-observe nano-probe. Both one- and two-dimensional experiments on arabinoxylan samples in the low nanomole range were performed, including 1H– 1H DQF-COSY, 1H– 1H TOCSY and 1H– 1H ROESY. These experiments allowed, in combination with MALDI-TOF MS and literature NMR data, a complete structural determination of several tetra-, penta-, hexa- and heptasaccharides. Two new structures: α- l-Ara f-(1→2)-β- d-Xyl p-(1→4)-β- d-Xyl p-(1→4)-β- d-Xyl p-(1→4)- d-Xyl p and α- l-Ara f-(1→2)[α- l-Ara f-(1→3)]-β- d-Xyl p-(1→4)-β- d-Xyl p-(1→4)-β- d-Xyl p-(1→4)- d-Xyl p) were characterized, as well as some previously published structures.