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-d(6) solution. These mannosides, Man alpha(1 -> 2)Man alpha OMe (1) Man alpha(1 -> 3)Man alpha OMe (2), Man alpha(1 -> 6)Man alpha OMe (3), Man alpha(1 -> 2)Man alpha(1 -> 2)Man alpha OMe (4), Man alpha(1 -> 2)Man alpha(1 -> 3)Man alpha OMe (5), Man alpha(1 -> 2)Man alpha(1 -> 6)Man alpha OMe (6) and Man alpha(1 -> 3)[Man alpha 1 -> 6]Man alpha OMe (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.

Ämnesord

NATURVETENSKAP  -- Kemi -- Organisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Organic Chemistry (hsv//eng)

Nyckelord

NMR

H-1

hydroxy protons

dimannosides

trimannosides

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