TABLE 2.
Structural data for muropeptides 3Am and 7Ama
| Peak | Amt (nmol) of:
|
Predicted structure | (M-H)−m/zb
|
||||||
|---|---|---|---|---|---|---|---|---|---|
| Glucosamine | Muramitol | Muramic-δ-lactam | Ala | Glu | Dpm | Calc. | Obs. | ||
| 3Am | 1 (1) | 0.95 (1) | 0 | 2.94 (3) | 1.84 (2) | 2.25 (2) | DS-TriP-TP | 1311.56 | 1312.47 |
| 7Am | 1 (2) | 0.48 (1) | 0.35 (1) | 0 | 0 | 0 | TS | 915.36 | 917.10 |
a
Peaks are numbered as in Fig. 1. All nanomole values were determined using amino acid and amino sugar analyses (24) and were normalized to a value of 1 for NAG. NAM residues at the reducing ends of muropeptides and muramic-δ-lactam were detected as muramitol and muramic acid, respectively, in the amino acid analysis. Values in parentheses are predicted numbers of moles of the residues within the molecule.
b
(M-H)− is the deprotonated molecular ion observed in the negative-ion mode. Calc., predicted from the amino acid and amino sugar analyses, with the average mass values given; obs., measured by matrix-assisted laser desorption ionization–time of flight mass spectrometry.