Hydrogen bonds (Hbonds) are a recurrent structural feature found in biological molecules, such as proteins and nucleic acids. Hbonds help stabilize biological structural motifs in proteins, DNA and RNA, supported by a wealth of direct evidence in solution. However, direct evidence for Hbonds in glycans dissolved in aqueous solution has been lacking until recently. The best tool for directly detecting Hbonds is solution NMR spectroscopy because it offers atomic resolution and the potential to directly establish Hbond donor and acceptor pair via <i>J</i>-couplings. Thus, Hbonds' directionality can also be determined. Hbonds expected in glycans are different than those in proteins and nucleic acids, where the NH-based Hbonds are far more prominent and also dictates structure. Hbonding in glycans is thought to occur between multiple OH groups. Since OH in glycans are considered similar to those in H<sub>2</sub>O, internal Hbonds are believed not to provide significant structural stabilization to yield long-lived conformations. Consequently, Hbonds are likely transient, and therefore harder to detect than for other biomolecules. However, their detection may provide direct evidence of the presence of defined conformations, even while multiple conformations may exist simultaneously in equilibrium. In this context, our group considers detection of Hbonds a valuable tool for the characterization of a glycan’s conformational space. In our recent work, we have detected NH→O, OH→OH, OH→O=C and CH→O Hbonds. In this talk, we report our progress towards detecting and characterizing Hbonds in glycans by direct NMR measurements.

Hydrogen bonding in the conformations of glycans

2019 Fall National Meeting

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