CONFORMATIONAL BEHAVIOR OF OLIGO-GALACTOMANNAN CHAINS INFERRED FROM NMR-SPECTROSCOPY AND MOLECULAR MODELING

An investigation of the solution conformation of oligo-galactomannans has been carried out. It consists first in the study of the conformati onal behavior of two model disaccharides (mannobiose and epimelibiose) of galactomannans through combined NMR and molecular modeling. H-1-H- 1 NOE and (3)J((C,H)) coupling constants across glycosidic bonds have been measured and compared to results of conformational analysis using the PCILO quantum chemical method, to define the stable conformers, a nd the SOLVOL program, to take into account the solvent effects. From these results, helical and statistical conformations of oligomers were then generated. The structures obtained are discussed in terms of the influence of the position and number of galactose units upon the conf ormation of the mannose backbone.