Figure 5.

Identification and tentative structural assignment of novel GDGT IPLs produced by T. kodakarensis. IPLs containing a GDGT core lipid were deduced via fragmentation patterns, retention times, and parent ion masses identified after ion trap-MS and Q-TOF-MS. Expected mass losses of known headgroup moieties are illustrated in the dark gray box and correspond to daughter ions identified in the MS/MS spectra. The daughter ions labeled with dotted lines in the MS/MS spectra refer to a loss of water (18 Da) from fragments identified in the dark gray box. (A) IPL-17; the 161 Da loss and elemental formula are consistent with the loss of a Hex(NH₂) or Hex, as in Figure 4C, yielding the PI-GDGT daughter ion (m/z = 1544 Da). (B,C) IPL-18 and IPL-19; the similar fragmentation patterns and mass difference of parent ions of these IPLs are parallel to the headgroups identified in IPLs-9 and 10 (Figures 4C,D). In the case of IPL-19, the 1705 Da daughter ion is consistent with IPL-17 after the loss of a PI moiety. (D) IPL-20; the 1544 Da fragment identifies PI-GDGT after the loss of one PI moiety.