Conformational analysis of the neutral exopolysaccharide produced by Lactobacillus delbrueckii ssp. bulgaricus LBB.B26

Abstract

The conformational properties of the neutral exopolysaccharide produced by Lactobacillus delbrueckii ssp. bulgaricus LBB.B26 have been studied by NMR measurements and molecular modelling. The exopolysaccharide, with an average molecular mass of 1.3 × 10⁶ Da, was previously determined to consist of pentasaccharide repeating units with the following structure: →3)-β-D-Galp-(1→4)-β-D-Glcp-(1→3)-β-D-Galf-(1→3)-[α-D-Glcp-(1→6)-]α-D-Galp-(1→. Adiabatic maps were generated for each of the disaccharide fragments in the repeating unit. In addition, free energy maps calculated from MD simulations were obtained for each of the glycosidic linkages in an extended repeating unit and the influence of the Galf residue on the conformational properties of the repeating unit was investigated. The values of the global energy minima provided by the free energy maps were used to build a polymer chain. The polysaccharide was shown to have a random coil structure, without stable extended helical motifs.