Fig. 4.

a³¹P NMR showing the comparison of lipidome samples containing PB (unbroken line, unstarred labels) and not containing it (dashed line, starred labels); b¹H, ¹H TOCSY showing through bond coupling identifying glyceryl–sn-1-3 (panel, left) and butyl (B1-B4) protons (panel, right). Projections shown opposite the x and y axes indicate protons coupled to ³¹P and are taken from a slice through a ³¹P,¹H HSQC experiment at the ³¹P chemical shift of 0 · 34 ppm (characteristic of PB in a 1D ³¹P experiments, (a)). The subscript notations used above are the same as the notations in Supplementary Figure 20