Figure 2

Characterization of aminoethylphosphonate (AEPn)-containing SP in T. cruzi by tandem mass spectrometry (MS/MS). (a) MS/MS of major ion found in T. cruzi, with m/z 645 and eluting between 25–26 minutes. Daughter ions include m/z 264, diagnostic of a d18:1 LCB, m/z 280 from a 16:0 fatty acyl chain, m/z 520 and m/z 502. (b) MS/MS of a d18:1/16:0 EPC, the major EPC found in T. cruzi, with m/z 661 and eluting between 24–25 minutes. (c) Absence of signals with m/z 645 from T. brucei at 25–26 minutes. (d) MS/MS of a d18:1/16:0 EPC, the major EPC found in T. brucei, with m/z 661 and eluting between 24–25 minutes,. (e) MS/MS of major ion, with m/z 645, found in T. brucei cultured in the presence of AEPn, eluting between 25–26 minutes. Fragmentation reveals several daughter ions including m/z 264, diagnostic of a d18:1 LCB, m/z 280 from a 16:0 fatty acyl chain, m/z 520 and m/z 502, which result from neutral loss of AEPn and subsequent loss of water. This confirms the T. cruzi lipid to be a d18:1/16:0 AEPnC. (f) MS/MS of a d17:1/12:0 EPC synthetic standard. Daughter ions include m/z 250, diagnostic of a d17:1 LCB, m/z 224 from a 12:0 fatty acyl chain, m/z 450 and 432, arising from neutral loss of phosphoethanolamine and subsequent loss of water. (g) Structure of d18:1/16:0 AEPn-containing ceramide (AEPnC). Sites of fragmentation by collision-induced dissociation are shown - x, y and z denotes fragments arising from the LCB, the fatty acyl moiety and ion from the neutral loss of the AEPn headgroup respectively. (h) Structure of d18:1/16:0 EPC. Sites of fragmentation by collision-induced dissociation are shown, where x, y and z denotes fragments arising from the LCB, the fatty acyl moiety and ion from the neutral loss of the phosphoethanolamine headgroup respectively.