FIG. 2.

Proposed structure of muropeptide 7A. The DSs (N-acetylglucosamine–N-acetylmuramic acid) have the peptide side chains linked to the muramic acid residues. The peptides have the d-Glu residues linked through their γ-carboxyls to the α-amino groups of Dpm. The peptide cross-link is formed between the d-Ala carboxyl and the ε-amino group of the Dpm. The Gly residues in brackets are the positions where this residue can be linked to the α-carboxyl (a) and ω-carboxyl (b) of the Dpm in the acceptor peptide, respectively.