Table 2.
Mass spectrometric analysis of LOS from Neisseria meningitidis capsule null locus (cnl) strainsa
| Strain | Observed ions (m/z) |
Molecular mass (Da) |
Relative intensityb | Lipid A-OHc | Core OSd | Proposed composition | ||
|---|---|---|---|---|---|---|---|---|
| (M − 3H)3− | (M − 2H)2− | Observed | Calculated | |||||
| 2274 | 929.8 | 1,395.5 | 2,792.7 | 2,792.6 | 1.0 | 952 | 1,841 | 3Hex, 2HexNAc, PEtn, 2Hep, 2 Kdo, lipid A-OH |
| 2275 | 930.1 | 1,395.5 | 2,793.1 | 2,792.6 | 1.0 | 952 | 1,841 | 3Hex, 2HexNAc, PEtn, 2Hep, 2 Kdo, lipid A-OH |
a
Negative-ion CE-MS and CE–ES–MS-MS data and proposed compositions of O-deacylated LOS are shown. Average mass units (in Da) were used for calculation of molecular masses, based on the proposed composition, as follows: Hex, 162.15; Hep, 192.17; HexNAc, 203.19; Kdo, 220.18; PEtn, 123.05.
b
Relative to most intense peak in mass spectrum.
c
As determined by MS-MS analyses, following introduction of separated LPS-OH glycoforms into the mass spectrometer by CE.
d
As deduced from lipid A-OH size determinations.