title: Probing the glycosidic linkage: UV and IR ion-dip spectroscopy of a lactoside.
abstract: The beta(1-->4) glycosidic linkage found in lactose is a prevalent structural motif in many carbohydrates and glycoconjugates. Using UV and IR ion-dip spectroscopies to probe benzyl lactoside isolated in the gas phase, we find that the disaccharide unit adopts only a single, rigid structure. Its fully resolved infrared ion-dip spectrum is in excellent agreement with that of the global minimum structure computed ab initio. This has glycosidic torsion angles of phi(H) (H1-C1-O-C4') approximately 180 degrees and psi(H) (C1-O-C4'-H4') approximately 0 degrees which correspond to a rotation of approximately 150 degrees about the glycosidic bond compared to the accepted solution-phase conformation. We discuss the biological implications of this discovery and the generality of the strategies employed in making it.
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Jockusch
authors.forename: Romano T
authors.initials: RT
authors.lastname: Kroemer
authors.forename: Francis O
authors.initials: FO
authors.lastname: Talbot
authors.forename: Lavina C
authors.initials: LC
authors.lastname: Snoek
authors.forename: Pierre
authors.initials: P
authors.lastname: Carçabal
authors.forename: John P
authors.initials: JP
authors.lastname: Simons
authors.forename: Martina
authors.initials: M
authors.lastname: Havenith
authors.forename: Joost M
authors.initials: JM
authors.lastname: Bakker
authors.forename: Isabelle
authors.initials: I
authors.lastname: Compagnon
authors.forename: Gerard
authors.initials: G
authors.lastname: Meijer
authors.forename: Gert
authors.initials: G
authors.lastname: von Helden
mesh_terms: D006027:Glycosides / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006027:Glycosides; D007477:Ions; C008245:lactosides