Production of Glycopeptide Derivatives for Exploring Substrate Specificity of Human OGA Toward Sugar Moiety.

O-GIGNAcase (OGA) is the only enzyme responsible for removing N-acetyl glucosamine (GIcNAc) attached to serine and threonine residues on proteins. This enzyme plays a key role in O-GleNAc metabolism. However, the structural features of the sugar moiety recognized by human OGA (hOGA) remain unclear. In this study, a set of glycopeptides with modifications on the GIcNAc residue, were prepared in a recombinant full-length human OGT-catalyzed reaction, using chemoenzymatically synthesized UDP-GIcNAc derivatives. The resulting glycopeptides were used to evaluate the substrate specificity of hOGA toward the sugar moiety. This study will provide insights into the exploration of probes for O-GIcNAc modification, as well as a better understanding of the roles of O-GIcNAc in cellular physiology.