Table 3.
MALDI-TOF mass spectrometry of SEB-purified peptidoglycan fragments
|
m/z observed1 |
m/z calculated | Δ (observed and calculated) |
Predicted structure2 | ||||
|---|---|---|---|---|---|---|---|
| femAB::308 | femAB::308 fmhA | femAB::308 fmhC | femAB::308 | femAB::308 fmhA | femAB::308 fmhC | ||
| 2234.88 | 2234.59 | 2234.87 | 2236.35 | 1.47 | 1.76 | 1.48 | [NH2-AQK-(NH2-H6AQALPET-G5)-A-COOH] H+ |
| 2257.20 | 2256.97 | 2257.20 | 2258.34 | 1.14 | 1.37 | 1.14 | 2236.35 |
| 2262.78 | 2263.12 | 2262.65 | 2264.34 | 1.56 | 1.22 | 1.69 | 2236.35 |
| 2278.34 | 2278.32 | 2280.44 | 2.10 | 2.12 | [NH2- AQK-(NH2-H6AQALPET-G3S1)-AA-COOH] H+ | ||
| 2284.82 | 2285.62 | 2285.10 | 2286.33 | 1.51 | 0.71 | 1.23 | 2258.34 formylated |
| 2300.70 | 2300.0032 | 2302.42 | 1.72 | 2.42 | 2280.44 sodiated | ||
| 2306.39 | 2307.28021 | 2305.776 | 2307.44 | 1.05 | 0.16 | 1.66 | [NH2-AQK-(NH2-H6AQALPET-G5)-A A-COOH] H+ |
| 2316.26 | 2315.9331 | 2316.42 | 0.16 | 0.49 | [NH2-AQK-(NH2-H6AQALPET-G4S1)-A-COOH] Na+ formylated | ||
| 2341.44 | 2341.06 | 2343.42 | 1.99 | 2.37 | [NH2-AQK-(NH2-H6AQALPET-G5)-Ala-[G1]-COOH] Na+ formylated | ||
1See Fig. 5 for the corresponding mass spectra.
2Adventitious formylation of peptides in the presence of TFA has been previously noted.