Background:

Proteins can be modified post-translationally by the addition of O-linked N-acetylglucosamine (O-GlcNAc). Nuclear cytoplasmic O-GlcNAcase and acetyltransferase (NCOAT) is a β-N-acetylglucosaminidase that removes GlcNAc from O-glycosylated proteins. PUGNAc is a (phenylcarbamoyl)oxime analog of GlcNAc that reversibly inhibits NCOAT (Ki = 40-110 nM).[1],[2] It also less potently inhibits other hexosaminidases and exochitinases.[2],[3],[4] (Z)-PUGNAc is a stereoisomer of PUGNAc that is a more potent inhibitor of NCOAT than the (E) isomer, both in vitro and in cells.[5]

Reference:
[1]. Horsch, M., Hoesch, L., Vasella, A., et al. N-Acetylglucosaminono-1,5-lactone oxime and the corresponding (phenylcarbamoyl)oxime. Novel and potent inhibitors of β-N-acetylglucosaminidase. European Journal of Biochemistry 197(3), 815-818 (1991).
[2]. Dong, D.L.Y., and Hart, G.W. Purification and characterization of an O-GlcNAc selective N-acetyl-β-D-glucosaminidase from rat spleen cytosol. The Journal of Biological Chemisty 269(30), 19321-19330 (1994).
[3]. Hodge, A., Gooday, G.W., and Alexander, I.J. Inhibition of chitinolytic activities from tree species and associated fungi. Phytochemistry 41, 77-84 (1996).
[4]. Macauley, M.S., Bubb, A.K., Martinez-Fleites, C., et al. Elevation of global O-GlcNAc levels in 3T3-L1 adipocytes by selective inhibition of O-GlcNAcase does not induce insulin resistance. The Journal of Biological Chemisty 283(50), 34687-34695 (2008).
[5]. Perreira, M., Kim, E.J., Thomas, C.J., et al. Inhibition of O-GlcNAcase by PUGNAc is dependent upon the oxime stereochemistry. Bioorganic & Medicinal Chemistry 14, 837-846 (2006).