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. 2010 Jun 28;78(9):3726–3735. doi: 10.1128/IAI.00225-10

FIG. 1.

FIG. 1.

Electrospray-MS characterization of total lipids of P. gingivalis and the highly enriched phosphoethanolamine dihydroceramide (PE DHC) or phosphoglycerol dihydroceramide (PG DHC) lipid fractions. Lipids were prepared and characterized by electrospray-MS as described in Materials and Methods. The upper frame shows the negative ions recovered in the total lipid extract of P. gingivalis lipids, the middle frame shows the ions recovered in the PE DHC lipid fraction, and the bottom frame shows the ions recovered in the PG DHC lipid fraction. A description of the MS interpretation of these ions and the structural deduction can be found in Nichols et al. (34). The PG DHC lipids include three component lipids that produce negative ions of 960, 946, and 932 m/z and, by analogy, the PE DHC lipids produce negative ions of 705, 691, and 677 m/z (34). Note that the dominant-negative ions previously reported for lipid A species of P. gingivalis (1,450, 1,690, and 1,770 m/z) (10) are not recovered in these lipid isolates.