Probing Glycosyltransferase Activities with the Staudinger Ligation

摘要

A fundamental challenge in the field of glycobiology is to identify the substrates and functions of the glycosyltransferases that build glycans within the secretory compartments. Numbering about 250 in humans, these enzymes assemble complex glycans by glycosyl transfer from nucleotide sugar donors. Although the specificities of glycosyltransferases for their glycosyl donors are usually well-defined, the profile of acceptors they can modify is not known for many enzymes. The development of microarray formats for peptide and carbohydrate display offers a new platform for rapid screening of glycosyltransferase acceptor specificities. However, a general nonradioactive method to detect glycosyltransferase products in array format has not been reported. The enzymes transfer various monosaccharides, defined by the enzyme subfamily (i.e., fucose for fucosyltransferases), to a variety of acceptor substrates. Some of their glycan products can be detected using specific antibodies or lectins, but no single detection method can be used with all members of the glycosyltransferase family.