title: NMR and conformational studies of linear and cyclic oligo-(1→6)-β-D-glucosamines.
abstract: The conformational behavior of a series of linear and cyclic oligo-(1→6)-β-D-glucosamines and their N-acetylated derivatives, which are related to fragments of natural poly-N-acetylglucosamine, was studied by theoretical molecular modeling and experimental determination of transglycosidic vicinal coupling constants (3)J(C,H) and (3)J(H,H). Molecular dynamics simulations were performed under several types of conditions varying in the consideration of ionization of amino groups, solvent effect, and temperature. Neural network clustering and asphericity calculations were performed on the basis of molecular dynamics data. It was shown that disaccharide fragments in the studied linear oligosaccharides were not rigid, and tended to have several conformers, thus determining the overall twisted shape with helical elements. In addition, it was found that the behavior of C5-C6 bond depended significantly upon the simulation conditions. The cyclic di-, tri-, and tetrasaccharides mostly had symmetrical ring-shaped conformations. The larger cycles tended to adopt more complicated shapes, and the conformational behavior of their disaccharide fragments was close to that in the linear oligosaccharides.
authors.affiliation: Laboratory of Glycoconjugate Chemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, 119991 Moscow, Russia.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Grachev
authors.forename: Alexey G
authors.initials: AG
authors.lastname: Gerbst
authors.forename: Marina L
authors.initials: ML
authors.lastname: Gening
authors.forename: Denis V
authors.initials: DV
authors.lastname: Titov
authors.forename: Olga N
authors.initials: ON
authors.lastname: Yudina
authors.forename: Yury E
authors.initials: YE
authors.lastname: Tsvetkov
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Pier
authors.forename: Nikolay E
authors.initials: NE
authors.lastname: Nifantiev
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*
chemical_list: D009844:Oligosaccharides; D005944:Glucosamine; D000117:Acetylglucosamine