Fig. 1.

Site-selective ¹³C incorporation in aromatic side-chains using site-selectively labeled erythrose. Phenylalanine, tyrosine and tryptophan (from top to bottom) are shown with the positions in the aromatic rings labeled. Incorporation of carbons from erythrose is shown in red, with the positions of erythrose (1–4) labeled. Other positions (shown in black) can be labeled if erythrose is scrambling into other pathways