CHAPTER 15. Reverse Synthesis of Natural Glycans

Glycans are a major class of biomolecules posing special synthetic challenges for biologists and chemists due to their inherent complex structures. One major problem for glycoscience is the lack of access to biomedically relevant complex glycan structures. Both chemical and enzymatic syntheses are yet to meet the demand resulting from quickly growing interest on glycoscience. As an alternative approach, complex glycans can be released and harvested from several classes of glycoconjugates presented in different organisms by reactions termed “reverse synthesis”. Many enzymatic and chemical approaches have been developed for the release of glycans from natural materials, many of which are designed for analytical glycomics study. Recent advances in the oxidative release of natural glycans (ORNG) using inexpensive reagents and a simple, scalable procedure can be used to produce large amount of natural glycans from several classes of glycoconjugates, providing potential to a viable “reverse synthesis” approach to enrich complex glycan libraries. This chapter summarizes the development of enzymatic and chemical methods for reverse synthesis of glycans with a special emphasis on the newly developed ORNG method.