Development of a (1)H NMR structural-reporter-group concept for the analysis of prebiotic galacto-oligosaccharides of the [β-d-Galp-(1→x)]n-d-Glcp type.

Some β-galactosidases (EC 3.2.1.23) are capable of producing mixtures of linear and branched galacto-oligosaccharides (GOS) with various types of glycosidic linkages [degree of polymerization (DP) 2-8; mainly GalnGlc] when incubated under specific conditions with lactose. These products are generally applied in infant formula. However, for most galacto-oligosaccharide products only major components (low DP) or linkage patterns have been described. To build up a library of (1)H and (13)C NMR data, a detailed NMR study on commercially available GOS di- and trisaccharides, and some larger GOS oligosaccharides was carried out. Based on the fully assigned (1)H and (13)C chemical shifts of these model compounds, a (1)H NMR structural-reporter-group concept was formulated to function as a tool in the structural analysis of single GOS components and GOS mixtures.