Trisaccharides, solution conformation

C-N.m.r. lines have been assigned to the terminal, central and directly attached monosaccharide residues in a triterpenoid saponin with a trisaccharide moiety, on the basis of decreasing spin-lattice relaxation times, the so-called "partially relaxed Fourier transform" method. The solution conformation of acarbose (16) has been determined by H and n.O.e. n.m.r. techniques and compared with that predicted by hard-sphere exo-anomerlc effect calculations. 

The H- and C-NMR spectra of aclacinomycin A have been fully assigned, and the results were used in a study of the solution conformation of the trisaccharide 22 of this antibiotic. The related trisaccharide 23 of ditrisarubidn B and betaclacamydn has been synthesized and its DNA-binding was studied. It was found that the DNA binding of the trisaccharide is low, indicating the need for the chromophere to anchor the antibiotic in the DNA. ... 

The unusual properties of xanthan undoubtedly result from its stmctural rigidity, which in turn is a consequence of its Linear, ceUulosic backbone that is stiffened and shielded by the trisaccharide side chains. The conformation of xanthan in solution is a matter of debate. It does appear that the conformation changes with conditions. 

The 3H chemical shifts, coupling constants, temperature coefficients, exchange rates and inter-residual ROEs of the hydroxyl protons of various synthetic type II trisaccharides, analogues of (3-D-Galp-(l - 4)-p-D-GlcpNAc-(l - 2)-a-D-Man-(l - 0)(CH2)7CH3, were reported and interpreted,8 assisted with molecular dynamic simulations, to deduce key information on the conformational behavior of these important molecules in aqueous solution. 

A trisaccharide fragment of the jV-type oligosaccharides (oc-D-Man-(l-3)-p-D-Man-(l-4)- 3-D-Glc.VAc) including the central P-D-Man has been obtained as single crystals. The dihedral angles of the glycosidic bonds which were obtained from an X-ray analysis are summarized in Fig. 9 [ 137]. This conformation is very closely related to the conformations calculated or determined experimentally in solution by NMR... 

Among GAG, conformation of HA in solution (6,9,25-33) and in solid state (39,35,36,37) has been studied most. We have recently prepared oligosaccharides of HA, starting from di- to dodecasaccharide according to reported methods (3S,39). We have also succeeded in making some trisaccharides by glucuronidase digestion of tetrasaccharides (39). 

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