title: Glycan OH Exchange Rate Determination in Aqueous Solution: Seeking Evidence for Transient Hydrogen Bonds.
abstract: Hydrogen bonds (Hbonds) are important stabilizing forces in biomolecules. However, for glycans in aqueous solution, direct NMR detection of Hbonds is elusive because of their transient nature. Here, we present Isotope-based Natural-abundance TOtal correlation eXchange SpectroscopY (INTOXSY), a new1H-13C heteronuclear single quantum coherence-total correlation spectroscopy based method, to extract OH groups' exchange rate constants (kex) for molecules in natural13C abundance and show that OH Hbonds can be inferred from "slower" H/D kex. We evaluate kexmeasured with INTOXSY in light of those extracted with line-shape analysis. Subsequently, we use a set of common glycans to establish a kexreference basis set and to infer the existence of transient Hbonds involving OH donor groups. Then, we report kexvalues for a series of mono- and disaccharides, as well as for oligosaccharides sialyl Lewis X and β-cyclodextrin, and compare the results with those from the reference set to extract Hbond information. Finally, we utilize NMR experimental data in conjunction with molecular dynamics simulations to establish donor and acceptor Hbond pairs. Our exchange rate measurements indicate that OH/OD exchange rates, kHD, values <10 s-1are consistent with transient Hbond OH groups and potential acceptor groups can be uncovered through MD simulations.
authors.affiliation: Laboratory of Bacterial Polysaccharides, Center for Biologics Evaluation and Research, Food and Drug Administration , 10903 New Hampshire Avenue, Silver Spring, Maryland 20903, United States.
authors.forename: Marcos D
authors.initials: MD
authors.lastname: Battistel
authors.affiliation: Laboratory of Bacterial Polysaccharides, Center for Biologics Evaluation and Research, Food and Drug Administration , 10903 New Hampshire Avenue, Silver Spring, Maryland 20903, United States.
authors.forename: Hugo F
authors.initials: HF
authors.lastname: Azurmendi
authors.affiliation: Laboratory of Bacterial Polysaccharides, Center for Biologics Evaluation and Research, Food and Drug Administration , 10903 New Hampshire Avenue, Silver Spring, Maryland 20903, United States.
authors.forename: Darón I
authors.identifier: 0000-0003-1991-5174
authors.initials: DI
authors.lastname: Freedberg
mesh_terms: D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011134:Polysaccharides / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D011134:Polysaccharides; D012996:Solutions; D014867:Water; D006859:Hydrogen; C031356:hydroxide ion