title: Molecular conformations of a disaccharide investigated using NMR spectroscopy.
abstract: The molecular structure of alpha-L-Rhap-(1--> 2)-alpha-L-Rhap-OMe has been investigated using conformation sensitive NMR parameters: cross-relaxation rates, scalar 3J(CH) couplings and residual dipolar couplings obtained in a dilute liquid crystalline phase. The order matrices of the two sugar residues are different, which indicates that the molecule cannot exist in a single conformation. The conformational distribution function, P(phi, psi) related to the two glycosidic linkage torsion angles phi and psi was constructed using the APME method, valid in the low orientational order limit. The APME approach is based on the additive potential (AP) and maximum entropy (ME) models. The analyses of the trajectories generated in molecular dynamics and Langevin dynamics (LD) computer simulations gave support to the distribution functions constructed from the experimental NMR parameters. It is shown that at least two conformational regions are populated on the Ramachandran map and that these regions exhibit very different molecular order.
authors.affiliation: Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91, Stockholm, Sweden.
authors.forename: Clas
authors.initials: C
authors.lastname: Landersjö
authors.forename: Baltzar
authors.initials: B
authors.lastname: Stevensson
authors.forename: Robert
authors.initials: R
authors.lastname: Eklund
authors.forename: Jennie
authors.initials: J
authors.lastname: Ostervall
authors.forename: Peter
authors.initials: P
authors.lastname: Söderman
authors.forename: Göran
authors.initials: G
authors.lastname: Widmalm
authors.forename: Arnold
authors.initials: A
authors.lastname: Maliniak
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003198:Computer Simulation; D004187:Disaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D004187:Disaccharides; C076977:rhamnopyranosyl-(1-2)-rhamnopyranoside-(1-methyl ether)