NMR study of hydroxy protons of di- and trimannosides, substructures of Man-9.
The chemical shifts, temperature coefficients and inter-residual rotating-frame Overhauser effect (ROE)s for the hydroxy protons of some alpha-(1,2)-, alpha-(1,3)- and alpha-(1,6)-linked di- and trimannosides have been measured for samples in 85% H2O/15% acetone-d6 solution. These mannosides, Manalpha(1-->2)ManalphaOMe (1) Manalpha(1-->3)ManalphaOMe (2), Manalpha(1-->6)ManalphaOMe (3), Manalpha(1-->2)Manalpha(1-->2)ManalphaOMe (4), Manalpha(1-->2)Manalpha(1-->3)ManalphaOMe (5), Manalpha(1-->2)Manalpha(1-->6)ManalphaOMe (6) and Manalpha(1-->3)[Manalpha1-->6]ManalphaOMe (7), are substructures of the N-glycan Man-9. The NMR data show that the hydration of each individual hydroxyl group in the di- and trisaccharides is very similar to the hydration of the corresponding hydroxyl in the monomeric methyl alpha-D-mannoside. No hydrogen-bond interactions were found to stabilize the conformations of the alpha-(1,2)- and alpha-(1,6)-linkages and the chemical shifts for the hydroxy proton resonances of the alpha-(1,6)-linkage indicated high-conformational flexibility. For the alpha-(1,3)-linkage, however, the downfield shift for the signal of O(2)H of the 3-substituted residue together with the ROE between this proton and H5' on the next residue suggest some weak inter-residue interactions.
Department of Chemistry, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
Birgit
B
Hakkarainen
Lennart
L
Kenne
Martina
M
Lahmann
Stefan
S
Oscarson
Corine
C
Sandström
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards*; D008362:Mannosides / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D011522:Protons; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013696:Temperature
D008362:Mannosides; D009844:Oligosaccharides; D011522:Protons