A peracetylated 4-nitrophenyl β-glycoside of N-acetylglucosamine (GlcNAc), in which the sugar hydroxyls are protected as acetate esters. The peracetate groups increase lipophilicity to facilitate cell membrane permeability, supporting use as a cell-permeable precursor or as a synthetic intermediate. Upon deprotection, the parent 4-nitrophenyl β-D-GlcNAc serves as a chromogenic substrate for β-N-acetylhexosaminidases (e.g., HexA/HexB, OGA), cleaving the β-glycosidic bond to release free GlcNAc and 4-nitrophenol. 4-Nitrophenyl (pNP) glycosides are chromogenic enzyme substrates: cleavage of the glycosidic bond by the target enzyme releases free 4-nitrophenol, which is yellow under basic conditions (absorbance maximum ~405 nm), enabling straightforward spectrophotometric assays of enzyme activity in solution and in high-throughput screening formats.