1 Centre for Applied Synthetic Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, QC, Canada H4B 2A6.
2 PROTEO, Quebec Network for Research on Protein Function, Structure, and Engineering, Quebec City, Quebec, Canada G1V 0A6.
3 Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB, Canada T6G 2G2.

Many glycosylated small molecule natural products and glycoprotein biologics are important in a broad range of therapeutic and industrial applications. The sugar moieties that decorate these compounds often show a profound impact on their biological functions, thus biocatalytic methods for controlling their glycosylation are valuable. Enzymes from nature are useful tools to tailor bioproduct glycosylation but these sometimes have limitations in their catalytic efficiency, substrate specificity, regiospecificity, stereospecificity, or stability. Enzyme engineering strategies such as directed evolution or semi-rational and rational design have addressed some of the challenges presented by these limitations. In this review, we highlight some of the recent research on engineering enzymes to tailor the glycosylation of small molecule natural products (including alkaloids, terpenoids, polyketides, and peptides), as well as the glycosylation of protein biologics (including hormones, enzyme replacement therapies, enzyme inhibitors, vaccines, and antibodies).