ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

On the Flexibility of the Lewis x, Lewis a, Sialyl Lewis x, and Sialyl Lewis a Oligosaccharides Conformational Analysis in Solution by Molecular Modelling

F. Bízik and I. Tvaroška

Institute of Chemistry, Slovak Academy of Sciences, SK-842 38 Bratislava

Abstract: The three-dimensional structure and conformational behaviour of the disaccharide α-D-Neu5Ac-(2→3)-β-D-Gal (I), two trisaccharides β-D-Gal-(1→3)-[α-L-Fuc-(1→4)]-β-D-GlcNAc (Lewis a, II) and β-D-Gal-(1→4)-[α-L-Fuc-(1→3)]-β-D-GlcNAc (Lewis x, III), and two tetrasaccharides α-D-Neu5Ac-(2→3)-β-D-Gal-(1→3)-[α-L-Fuc-(1→4)]-β-D-GlcNAc (sialyl Lewis a, IV) and α-D-Neu5Ac-(2→3)-β-D-Gal-(1→4)- [α-L-Fuc-(1→3)]-β-D-GlcNAc (sialyl Lewis x, V) in solution have been established using molecular modelling methods. The conformations available for each tri- and tetrasaccharide have been based on the minima available for disaccharide constituents of these oligosaccharides. The structure of the minima was calculated by molecular mechanics program RAMM which uses the MM2 force field in conjunction with the Monte Carlo simulation for a determination of the best side group orientations and with the evaluation of solvent effects, Abundances of conformers appear to depend strongly on the solvent. Comparison showed that calculated average vicinal carbon-proton coupling constants [³J_C,H] are in good agreement with available experimental data. These results imply that the flexibility of these compounds is larger than assumed up to now.

Full paper in Portable Document Format: 502a84.pdf

Chemical Papers 50 (2) 84–96 (1996)