TABLE 2.
Assignment of the main ions obtained by MALDI-TOF MS in the negative ion mode of lipid A from Xac wild type LPS (sugar backbone: [GlcNH2-GlcNH2])
| Acylation | Masscalc.a [M − H]− | Massmeas.b [M − H]− | PP-EtNH2 | P-EtNH2 | M-HOEtnH2 or M-PPEtNH2 |
|---|---|---|---|---|---|
| Penta-acylated | |||||
| c | 1685.9 | 1685.6 | 2 | ||
| 1671.9 | 1671.6 | 2 | |||
| 1657.8 | 1657.1 | 2 | |||
| 1643.9 | 1642.6 | 2 | |||
| 1629.9 | 1628.5 | 2 | |||
| 1615.9 | 1614.3 | 2 | |||
| 1601.9 | 1599.9 | 2 | |||
| d | 1577.8 | 1576.8 | 1 | 1 | |
| 1563.8 | 1562.1 | 1 | 1 | ||
| 1549.9 | 1548.1 | 1 | 1 | ||
| 1535.9 | 1534.2 | 1 | 1 | ||
| 1521.9 | 1521.3 | 1 | 1 | ||
| e | 1503.9 | 1504.4 | 1563.8–60 | ||
| 1490.8 | 1489.1 | 1549.9–60 | |||
| 1474.2 | 1473.4 | 1534.2–60 | |||
| 1461.3 | 1459.2 | 1521.3–60 | |||
| Tetra-acylated | |||||
| f | 1409.8 | 1408.6 | 1 | 1 | |
| 1395.8 | 1395.0 | 1 | 1 | ||
| 1381.8 | 1380.7 | 1 | 1 | ||
| 1367.7 | 1365.3 | 1 | 1 | ||
| 1353.7 | 1351.8 | 1 | 1 | ||
| h | 1177.8 | 1179.1 | 1 | 1381.8–204 | |
| 1163.7 | 1163.8 | 1 | 1367.7–204 | ||
| 1149.7 | 1149.5 | 1 | 1353.7–204 | ||
| Tri-acylated | |||||
| g | 1210.6 | 1209.6 | 1 | 1 | |
| 1196.6 | 1196.0 | 1 | 1 |
a calc., calculated monoisotopic masses.
b meas., measured monoisotopic masses.