Evaluation of the Chemical Reporter Analog PNP-6AzGlcNAc as an O-GlcNAcase Substrate

Abstract

6-Azido-6-deoxy-N-acetylglucosamine (6AzGlcNAc) was recently introduced as a new selective metabolic chemical reporter (MCR) for labeling O-GlcNAc-modified proteins in cells. To investigate whether O-6AzGlcNAc is readily cleaved by O-GlcNAcase (OGA), the enzyme responsible for removing the GlcNAc modification, we synthesized PNP-6AzGlcNAc. This analog mimics O-GlcNAc and can be used in vitro to define the kinetic parameters for OGA thereby defining whether O-6AzGlcNAc can be employed as an appropriate tool to monitor O-GlcNAc dynamics in cells. Both PNP-6AzGlcNAc and PNP-GlcNAc were efficiently hydrolyzed by OGA with similar kinetics suggesting that an azidomodification at the GlcNAc C6 position does not significantly interfere with the beta-hexosaminidase activity of OGA.