Figure 2.

Schematic of porphyrin-synthetic pathway to illustrate potential control points for increased PpIX accumulation. Enzymes, with names abbreviated and relative locations in the pathway shown in boxes are numbered beginning with the initial condensation of glycine and succinyl-CoA. Substrates/products are shown in bold font. The intracellular location of enzymes, relative to the mitochondria and the cytoplasm, is indicated.