TABLE 1 .
Proposed structures and molecular masses of PG fragments resulting from the digestion of M. lysodeikticus PG by purified His6-Cwp19
| Peaka | Proposed structureb |
m/z ([M+Na]+)c |
|
|---|---|---|---|
| Observed | Calculated | ||
| B | NAG-AnhNAM-l-Ala-d-iGlu-(Gly)l-Lys-d-Ala | 957.55 | 957.40 |
| C | NAG-AnhNAM-l-Ala-d-iGlu-(Gly)l-Lys-d-Ala | 957.55 | 957.40 |
| D | NAG-NAM-(l-Ala-d-iGlu-[Gly]l-Lys-d-Ala)NAG-NAM | 1,455.79 | 1,455.61 |
| E | NAG-AnhNAM-l-Ala-d-iGlu-(Gly)l-Lys-d-Ala-(d-Ala) | 1,028.59 | 1,028.44 |
| G | NAG-NAM-(l-Ala-d-iGlu-[Gly]-l-Lys-[d-Ala-l-Lys])NAG-NAM | 1,583.93 | 1,583.70 |
a
Peak letters correspond to Fig. 2.
b
The structures were deduced according to the previously determined structure of M. lysodeikticus PG (45). NAG, N-acetylglucosamine; NAM, N-acetylmuramic acid; AnhNAM, 1,6-anhydroNAM; iGlu, isoGlu.
c
Sodiated molecular ions are the most abundant on MALDI-TOF mass spectra for all PG fragments. m/z values correspond to monoisotopic masses.