title: NMR spectra of oligosaccharides at ultra-high field (900 MHz) have better resolution than expected due to favourable molecular tumbling.
abstract: Nuclear magnetic resonance (NMR) remains the most promising technique for acquiring atomic-resolution information in complex carbohydrates. Significant obstacles to the acquisition of such data are the poor chemical-shift dispersion and artifacts resultant from their degenerate chemical structures. The recent development of ultra-high-field NMR (at 900 MHz and beyond) gives new potential to overcome these problems, as we demonstrate on a hexasaccharide of the highly repetitive glycosaminoglycan hyaluronan. At 900 MHz, the expected increase in spectral dispersion due to higher resonance frequencies and reduction in strong coupling-associated distortions are observed. In addition, the fortuitous molecular tumbling rate of oligosaccharides results in longer T2-values that further significantly enhances resolution, an effect not available to proteins. Combined, the resolution enhancement can be as much as twofold relative to 600 MHz, allowing all 1H-resonances in the hexasaccharide to be unambiguously assigned using standard natural-abundance experiments. The use of ultra-high-field spectrometers is clearly advantageous and promises a new and exciting era in carbohydrate structural biology.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester Interdisciplinary Biocentre, Princess Street, Manchester M1 7ND, UK.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Blundell
authors.forename: Michelle A C
authors.initials: MA
authors.lastname: Reed
authors.forename: Michael
authors.initials: M
authors.lastname: Overduin
authors.forename: Andrew
authors.initials: A
authors.lastname: Almond
mesh_terms: D002240:Carbohydrate Sequence; D006820:Hyaluronic Acid / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D009844:Oligosaccharides; D006820:Hyaluronic Acid