Recent Developments in Enzymatic Synthesis of Modified Sialic Acid Derivatives

Sialic acid‐containing glycans play important roles in biology, but their synthesis by standard chemical approaches is challenging. Enzymatic assembly is generally a better approach. In the last two decades, a number of bacterial sialyltransferases (STs) and trans‐sialidases have been identified and a number of them found to exhibit broad substrate specificity. In this review, we will focus on the donor and acceptor substrate specificities of these enzymes along with the enzymatic routes employed to prepare sialosides bearing modifications at specific positions on the sialic acid carbon skeleton. Understanding the substrate tolerance of these enzymes will help researchers to choose the best biocatalyst for the assembly of specific sialosides, which can be valuable tools in the study of or inhibition of sialidases and STs and sialic acid‐binding proteins. In addition, the ability to study these processes using synthetic sialylated glycans will lead to a greater understanding of their biology and will lead to new therapeutic targets.