Chemo-Enzymatic Syntheses of Oligosaccharides and Glycoconjugates

The synthesis of homogeneous and well-defined glycan is important for detailed structural and functional studies of glycoscience and glycotechnology. Chemo-enzymatic synthesis of glycan maximizes the benefits of both chemical and enzymatic syntheses. This method enables the efficient synthesis of glycans by capitalizing on the high regio- and stereo-selectivity of enzymes in a well-used chemical synthesis where the number of steps and the time are spent. In this article, we describe the efficient synthesis of oligosaccharides by enzymatically adding saccharides to the synthesized core glycan, and the efficient synthesis of glycopeptides and glycoproteins by enzymatically binding glycan chains to chemically synthesized peptides and proteins. In particular, we describe in detail an efficient chemo-enzymatic synthesis of homogeneous and well-defined glycopeptides and glycoproteins by using the transglycosylation activity of microbial endoglycosidases and the chemically synthesized intermediate as a substrate. Furthermore, the application of this chemo-enzymatic method to the synthesis of bioactive substances and biopharmaceuticals is discussed, as well as the chemo-enzymatic glycoengineering and remodeling of sugar chains of glycoproteins.