peptidoglycan A peptidoglycosaminoglycan formed by alternating residues of β-(1→4)-linked <em>N</em>-acetylglucosamine and <em>N</em>-acetylmuramic acid {2-amino-3-<em>O</em>-[(<i>S</i>)-1-carboxyethyl]-2-deoxy-<small>D</small>-glucose} residues. Attached to the carboxy group of the muramic acid is a peptide chain of three to five amino acids. CHEBI:8005 peptidoglycosaminoglycan