title: A closer look at the nitrogen next door: 1H-15N NMR methods for glycosaminoglycan structural characterization.
abstract: Recently, experimental conditions were presented for the detection of the N-sulfoglucosamine (GlcNS) NHSO(3)(-) or sulfamate (1)H and (15)N NMR resonances of the pharmaceutically and biologically important glycosaminoglycan (GAG) heparin in aqueous solution. In the present work, we explore further the applicability of nitrogen-bound proton detection to provide structural information for GAGs. Compared to the detection of (15)N chemical shifts of aminosugars through long-range couplings using the IMPACT-HNMBC pulse sequence, the more sensitive two-dimensional (1)H-(15)N HSQC-TOCSY experiments provided additional structural data. The IMPACT-HNMBC experiment remains a powerful tool as demonstrated by the spectrum measured for the unsubstituted amine of 3-O-sulfoglucosamine (GlcN(3S)), which cannot be observed with the (1)H-(15)N HSQC-TOCSY experiment due to the fast exchange of the amino group protons with solvent. The (1)H-(15)N HSQC-TOCSY NMR spectrum reported for the mixture of model compounds GlcNS and N-acetylglucosamine (GlcNAc) demonstrate the broad utility of this approach. Measurements for the synthetic pentasaccharide drug Arixtra® (Fondaparinux sodium) in aqueous solution illustrate the power of this NMR pulse sequence for structural characterization of highly similar N-sulfoglucosamine residues in GAG-derived oligosaccharides.
authors.affiliation: Department of Chemistry, University of California-Riverside, Riverside, CA 92521, USA.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Langeslay
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Beni
authors.forename: Cynthia K
authors.initials: CK
authors.lastname: Larive
mesh_terms: D000606:Amino Sugars / Q000737:chemistry; D002240:Carbohydrate Sequence; D000077425:Fondaparinux; D006025:Glycosaminoglycans / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D009844:Oligosaccharides / Q000032:analysis; D010455:Peptides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D011522:Protons; D012996:Solutions; D012997:Solvents
chemical_list: D000606:Amino Sugars; D006025:Glycosaminoglycans; D009844:Oligosaccharides; D010455:Peptides; D011134:Polysaccharides; D011522:Protons; D012996:Solutions; D012997:Solvents; D006493:Heparin; D000077425:Fondaparinux; D009584:Nitrogen