N-Acetylglucosamine, or GlcNAc is a monosaccharide derivative of glucose. It is part of the bacterial cell wall, a biopolymer build from alternating units of N-acetyl glucosamine (GlcNAc) and N-acetyl muramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. The so formed layered structure is called peptidoglycan.

Membrane biology