Reverse-phase HPLC analysis of muropeptides derived from the peptidoglycan of wild-type E. coli CS109 and three mutants. The muropeptide peaks are labeled according to the abbreviations defined in Table 6. In B, C, and D, only those peaks that changed substantially from the preceding panel are labeled. (A) E. coli CS109. (B) E. coli CS12-7 (PBP 5 deleted). (C) E. coli CS357-3 (PBP 1a, PBP 5, and AmpH deleted). (D) E. coli CS420-2 (PBP 1a, PBP 5, AmpC, and AmpH deleted).