Glycosynthases: new enzymes for oligosaccharide synthesis

The mutation of putative acid/base and nucleophile of the active sites of retaining glycosyl hydrolases, together with kinetic analysis of the mutants, and stereochemical identification of products lead to useful information for the understanding of the reaction mechanism of these enzymes. This was the preliminary and fundamental step toward the preparation of new enzymatic activities called glycosynthases. Direct exploitation of this information has been possible, leading to the design of four new enzymes for oligosaccharides synthesis. The interest for these biocatalysts rises from the fact that the yield of the reaction can be increased and selectivity can be interpreted as key characteristic of the transfer reaction instead of a balance of hydrolytic and transferring pathways followed either by substrates and products. These new biocatalysts possess different specificities and are promising and useful tools in the construction of oligosaccharide molecules of great biological interest. This short review focused the attention on different glycosynthases obtained from four glycosyl hydrolases highlighting on the preparation and development of these new enzymes.