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

✍ Scribed by Doris Karibian; Alain Brunelle; Laurent Aussel; Martine Caroff

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 116 KB
• Volume: 13
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19991130)13:22<2252::aid-rcm783>3.0.co;2-g

✦ Synopsis

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.