FIG 6.

Analysis of L. lactis F44 PG by LC-MS. (A) Result for L. lactis F44-murF without addition of any d-amino acids. (B) LC-MS analysis of L. lactis F44-murF PG after growth in medium containing d-Met for 6 h. Peak 1 represents d-Met binding to Penta^Met, a disaccharide pentapeptide with the asparagine-peptide bridge. The structures and parameters are shown in Table 2. (C) LC-MS analysis of L. lactis F44-murF PG after growth in medium containing d-Phe for 6 h. Peaks 2 and 3 represent d-Phe binding to Penta^Phe, a disaccharide pentapeptide with the asparagine peptide bridge. Peak 4 represents d-Phe binding to Penta^Phe(X), a disaccharide (N-acetylglucosamine-N-acetylmuramyl) tetrapeptide with the aspartate peptide bridge and a molecule of water loss. Peaks 5, 6, and 7 represent d-Phe binding to Tetra^Phe, a disaccharide tetrapeptide with an aspartate peptide bridge. The structures and parameters are shown in Table 2.