Prebiotic galacto-oligosaccharides (GOS) are widely used in infant nutrition; they stimulate growth of healthly beneficial bacteria in the infant gut. GOS are synthesized by enzymatic trans-galactosylation of lactose, contain various β-type glycosidic linkages, and have chain lengths between 2 and 10.
The aim of our research was to decorate GOS with sialic acid to obtain sialylated GOS (Sia-GOS), a novel product expected to have broadened functionalities. Human milk is particularly rich in sialylated oligosaccharides (SOS), which play an important role in prevention of pathogen adhesion in the infant gut. Since SOS are only present in very low concentrations in cow milk, infant formulae are also 'deficient' in SOS, thus creating a demand for commercially available SOS in the infant food industry.
We employed the trans-sialidase from Trypanosoma cruzi (TcTS) expressed in E. coli, a recombinant enzyme with the unique ability to transfer (α2-3)-linked sialic acid from various glycoconjugates to acceptors containing a terminal β-linked galactose, to mediate sialic acid transfer from Κ-casein-derived glycomacropeptide to GOS. Product mixtures thus obtained ideally combine the prebiotic properties of GOS and expected anti-adhesive effects of Sia-GOS, making infant and baby foods resemble human milk more.
Here, we demonstrate the successful use of TcTS as a catalyst to synthesize sialylated galacto-oligosaccharides and show detailed analysis of the products formed.
Acknowledgements
This project is jointly financed by the European Union, European Regional Development Fund and The Ministry of Economic Affairs, Agriculture and Innovation, Peaks in the Delta, the Municipality of Groningen, the Provinces of Groningen, Fryslan and Drenthe as well as the Dutch Carbohydrate Competence Center (CCC WP6).
