Probing the glycosidic linkage: UV and IR ion-dip spectroscopy of a lactoside.
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.
Jockusch
Rebecca A
RA
Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom.
Kroemer
Romano T
RT
Talbot
Francis O
FO
Snoek
Lavina C
LC
Carçabal
Pierre
P
Simons
John P
JP
Havenith
Martina
M
Bakker
Joost M
JM
Compagnon
Isabelle
I
Meijer
Gerard
G
von Helden
Gert
G
D006027:Glycosides / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D006027:Glycosides; D007477:Ions; C008245:lactosides