Glycosynthases as tools for the production of glycan analogs of natural products.

Oligo-, polysaccharides, and glycoconjugates are a relevant part of the bioactive components of the natural products exploited in therapeutics, diagnostics, food additives, and biomaterials. Glycans are directly involved in important biological processes, such as immunostimulation, anti-inflammatory, antioxidant, and chemoprotectant actions and/or are crucial for their activity, by modulating target recognition, stability, and pharmacokinetics. On the other hand, carbohydrate extracts used for functional studies are rather heterogeneous and lack structural information because of their intrinsic complexity hampering purification and characterization. Therefore, methods for glycoside synthesis and modification are urgently needed. Recently, glycosynthases, engineered glycoside hydrolases with no hydrolytic activity that synthesize glycans in quantitative yields, were introduced. Here we will illustrate how the glycosynthases described so far might be exploited for the production of glycan analogs of natural products and their enormous potential in this field.