N-Acetylglucosamine (N-acetyl-D-glucosamine, or GlcNAc, or NAG) is a derivative of . It is an amide between and . It has a molecular formula of 8156, a of 221.21 g/mol, and it is significant in several biological systems.
It is part of a biopolymer in the bacterial , built from alternating units of GlcNAc and (MurNAc), cross-linked with at the residue of MurNAc. This layered structure is called .
GlcNAc is the monomeric unit of the polymer , which forms the outer coverings of and . GlcNAc is also of note in , where it is thought to be an atypical functioning in nocioceptive () pathways.
Polymerized with it forms .