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Biopolymers 2012 Mar;97(3):145-54

Transient hydrogen bonding in uniformly 13C, 15N labeled carbohydrates in water.

Norris SE, Landström J, Weintraub A, Bull TE, Widmalm G, Freedberg DI

Abstract

We report NMR studies of transient hydrogen bonding in a polysaccharide dissolved in water without co-solvent at ambient temperature. The polysaccharide portion of the Escherichia coli O142 lipopolysaccharide is comprised of repeating pentasaccharide units of GalNAc (N-acetyl galactosamine), GlcNAc (N-acetyl glucosamine) and rhamnose in a 3:1:1 ratio, respectively. A 105 ns MD (molecular dynamics) simulation on one pentasaccharide repeat unit predicts transient interresidue hydrogen bonds from the GalNAc NH groups in the polysaccharide. To investigate these predictions experimentally, the polysaccharide was uniformly (13) C,(15) N enriched and the NH, carbonyl, C2, C4 and methyl resonances of the GalNAc and GlcNAc residues assigned using through-bond triple-resonance NMR experiments. Temperature dependence of amide NH chemical shifts and one-bond NH J couplings support that NH groups on two of the GalNAc residues are donors in transient hydrogen bonds. The remaining GalNAc and GlcNAc NHs do not appear to be donors from either temperature-dependent chemical shifts or one-bond NH J couplings. These results substantiate the presence of weak or partial hydrogen bonds in carbohydrates, and that MD simulations of repeating units in polysaccharides provide insight into overall polysaccharide structure and dynamics.


Category: Journal Article
PubMed ID: #21858784 DOI: 10.1002/bip.21710
Includes FDA Authors from Scientific Area(s): Biologics
Entry Created: 2011-10-03 Entry Last Modified: 2012-08-29
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