Glycosylation with activated sugars using glycosyltransferases and transglycosidases

Abstract

The growing recognition of the roles of carbohydrates in fundamental biological processes and their potential application as functional foods and new therapeutics have generated a requirement for the general availability of larger amounts of varying carbohydrate structures.Thus the synthesis of oligo-, polysaccharides and glycosylated substances/products represents a major challenge.Activated sugars are key substrates for synthesis and glycosylation. Nucleotide activated sugars are natural tools for highly selective synthesis, providing complex polysaccharides, glycopeptides, glycolipids etc. However their high cost and availability limit their application. Sucrose acts as an activated substrate for a range of sucrase enzymes elaborating natural polysacchrides of the glucan and fructan type, which also serve for the synthesis and technical production of different oligosaccharides. Sucrose analogues have been shown to extend the range of oligosaccharide synthesis making new structures available incorporating further monosaccharides, such as mannose, galactose, xylose, rhamnose and fucose. A short overview of the use of glycosyl phosphates and glycosyl fluorides as substrates is also given.