CONFORMATION of the UNSATURATED URONIC-ACID RESIDUES of GLYCOSAMINOGLYCAN DISACCHARIDES
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Data
1993-01-01
Autores
Ragazzi, M.
Ferro, D. R.
Provasoli, A.
Pumilia, P.
Cassinari, A.
Torri, G.
Guerrini, M.
Casu, B.
Nader, H. B.
Dietrich, C. P.
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Molecular mechanics calculations (using the REFINE package) have been performed on a series of disaccharides obtained by cleavage of glycosaminoglycans with lyases, in order to examine the effect of chemical environment on the conformation of the 4,5-unsaturated uronic acid residue. the disaccharides were derived from heparin and heparan sulfate (1-5), hyaluronic acid (6), chondroitin (7), chondroitin-4-sulfate (8), and chondroitin-6-sulfate (9). the H-1 NMR spectra were analysed for the above compounds and for the unsaturated uronic acid residues of a low-molecular weight E. Coli K5 polysaccharide (10), as well as for the alditol derivative (11) of compound 8; the wide variation of the interproton vicinal coupling constants as a function of configuration and position of the glycosidic linkages and of the sulfation pattern is unequivocally interpreted in terms of equilibrium between two distinct ring forms, namely H-2(1) and H-1(2). the equilibrium is semi-quantitatively explained by the results of the present energy calculations.
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Journal of Carbohydrate Chemistry. New York: Marcel Dekker Inc, v. 12, n. 4-5, p. 523-535, 1993.