Table 5.
Interpretation of negative-ion mode MALDI-TOF mass spectra of fraction 5 isolated from E. coli R3 LOS preparation.
| Oligosaccharide Structure | Calculated Monoisotopic Mass (Da) | Observed Ion (m/z) |
Calculated Ion (m/z) |
Interpretation of the Ion |
|---|---|---|---|---|
| [ECA]4-FucNAc-OAc3 | 2760.02 | 2759.94 | 2759.01 | [M-H]− |
| [ECA]4-FucNAc-OAc3 | 2760.02 | 2741.93 | 2740.99 | [M-H2O-H]− |
| [ECA]4-FucNAc-OAc2 | 2718.01 | 2717.90 | 2717.00 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-Kdo-P3 | 1905.45 | 1904.49 | 1904.44 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-Kdo-P3-Etn | 1948.49 | 1947.51 | 1947.48 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-Kdo-P3-Etn | 1948.49 | 1929.53 | 1929.47 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P1 | 1948.60 | 1947.63 | 1947.59 | [M-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P1 | 1948.60 | 1929.60 | 1929.57 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P2 | 2028.66 | 2027.59 | 2027.55 | [M-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P2 | 2028.66 | 2009.58 | 2009.54 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P2-Etn | 2071.60 | 2070.68 | 2070.60 | [M-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P2-Etn | 207.160 | 2052.62 | 2052.58 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P3-Etn | 2151.57 | 2150.59 | 2150.56 | [M-H]− |
| Glc3-Gal-GlcNAc2-Hep3-Kdo-P3-Etn | 2151.57 | 2132.57 | 2132.55 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P1 | 1906.58 | 1887.63 | 1887.56 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P1 | 1906.58 | 1905.61 | 1905.58 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P2 | 1986.55 | 1967.57 | 1967.53 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P2 | 1986.55 | 1985.56 | 1985.54 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P2-Etn | 2029.59 | 2010.64 | 2010.57 | [M-H2O-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P2-Etn | 2029.59 | 2028.63 | 2028.59 | [M-H]− |
| Glc3-Gal-GlcNAc-Hep3-GlcN-Kdo-P3-Etn | 2109.56 | 2108.59 | 2108.55 | [M-H]− |
Three detected core OS R3 glycoforms were colored in green, blue, and red.