Fig 6.

ESI-MS/MS of dominant phosphorylated lipid A species (negative ions). The dominant phosphorylated lipid A species (m/z 1,418, 1,404, 1,390, and 1,376) generated through post-ion source de-esterification and desaturation (Fig. 1A and B) were evaluated for characteristic product ions resulting from collision induced dissociation. The product ions produced from these precursor ions are depicted for the mass range m/z 400 to 1,500. (D) The ESI-MS/MS spectrum for the m/z 1,418 monophosphorylated lipid A ion shown was used to reconcile the loss of fatty acids, as proposed in Fig. 1. Loss of fatty acids from the remaining lipid A species (A to C) are reconciled in Tables 2 and 3.