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Temperature dependencies of amide 1H- and 15N-chemical shifts in hyaluronan oligosaccharides

✍ Scribed by Charles D. Blundell; Andrew Almond

Publisher: John Wiley and Sons
Year: 2007
Tongue: English
Weight: 207 KB
Volume: 45
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1969

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✦ Synopsis

Abstract

Temperature coefficients (Δδ/ΔT) of amide chemical shifts of N‐acetylglucosamine residues have been measured in a range of oligosaccharides of the important vertebrate polysaccharide hyaluronan. Odd‐ and even‐numbered oligosaccharides with glucuronic acid, Δ‐4,5‐unsaturated glucuronic acid and N‐acetylglucosamine at the termini were investigated. All amide proton temperature coefficients were only slightly less negative (−6.9 to − 9.1 ppb/ °C) than those of amide protons in free exchange with water (≈− 11 ppb/ °C), indicating an absence of persistent intramolecular hydrogen bonds. With the exception of amide groups in reducing‐terminal N‐acetylglucosamine rings, all amide proton environments have the same temperature coefficient (−6.9 ppb/ °C), irrespective of differences in amide group chemical shifts and ^3^J~HH~ coupling constants, i.e. they do not sense subtle differences in orientation of the amide group. Amide nitrogen temperature coefficients report the same phenomena but with greater sensitivity. These data provide a set of reference values for temperature coefficients measured in other carbohydrates with acetamido sugars. Copyright © 2007 John Wiley & Sons, Ltd.

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