252Cf-plasma desorption mass spectrometry of unmodified lipid A: fragmentation patterns and localization of fatty acids

Rapid Commun Mass Spectrom. 1999;13(22):2252-9. doi: 10.1002/(SICI)1097-0231(19991130)13:22<2252::AID-RCM783>3.0.CO;2-G.


The fragmentation patterns of synthetic Escherichia coli-type lipid A in plasma desorption mass spectrometry (PDMS) in both negative- and positive-ion modes were determined. Negative-ion spectra gave signals for the main diphosphorylated (intact) molecular species in their native proportions. Intact and alkaline-treated lipid A in this mode gave, for the glucosamine I moiety, easily identified signals that have not been previously reported in PDMS. These spectra gave enough information to localize the fatty acids. The procedure was verified with relatively homogeneous lipids A prepared from Salmonella minnesota R595 and Neisseria meningitidis lipopolysaccharides, and then applied to the previously unstudied Yersinia entercolitica O:11,24 lipid A to obtain the localization of its fatty acids. The possibility of obtaining this much information from two negative-ion spectra was attributed to the method, described earlier, of preparing the samples. In the positive-ion mode, about half of the E. coli ions containing diglucosamine appeared as monodephosphorylated species and/or as Na adducts. The intact glucosamine II moiety and its fragment ions gave signals none of which were Na adducts. With lipids A prepared from S. minnesota, N. meningitidis, and Y. enterocolitica, similar fragmentation patterns were observed. For lipid A structure determination, the positive-ion mode could play a confirmatory role. The above results and some of those reported by others were compared.

MeSH terms

  • Escherichia coli / chemistry*
  • Fatty Acids / analysis*
  • Glucosamine / analysis
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Lipid A / chemistry*
  • Lipopolysaccharides / analysis
  • Mass Spectrometry / methods*
  • Molecular Structure
  • Neisseria meningitidis / chemistry
  • Salmonella / chemistry
  • Static Electricity
  • Yersinia enterocolitica / chemistry


  • Fatty Acids
  • Lipid A
  • Lipopolysaccharides
  • Glucosamine