FIGURE 3.

HPLC elution profile of C. jejuni muropeptides and proposed muropeptide structures. Purified PG was digested with cellosyl, and the resulting muropeptides were reduced with sodium borohydride and separated on a Prontosil 120-3-C18 AQ reverse-phase column. HPLC profiles are shown for C. jejuni wild-type 81-176 (A), Δpgp2 (B), the complement Δpgp2c (C), and the double mutant Δpgp1Δpgp2 (D). Peak numbers correspond to the main muropeptide fractions (11) whose structures are shown in E. G, N-acetylglucosamine; M, reduced N-acetylmuramic acid; d-iGlu, d-isoglutamic acid; Ac, O-acetyl groups at the C-6 hydroxyl group of MurNAc; Anh, 1,6-anhydro group at MurNAc. *, it is not known on which MurNAc residue the modification occurs.