Protoporphyrinogen synthetase

Dibenzofurans (Phe furan Phe) include various fungal infection-induced plant antifungal compounds (phytoalexins) such as the Rosaceae-derived cotonefuran (from Cotoneaster lactea) and a-pyrofurans (from Pyrus communis). Usnic acid from lichens (notably Usnea species) is anti-mycobacterial, anti-mitotic, an uncoupler and a potent inhibitor of plant protoporphyrinogen synthetase and 4-hydroxphenylpyruvate dioxygenase. 

The enzymes of the heme biosynthetic chain have a special distribution [Sano and Granick, 26]. Of the eight enzymes (Fig. 2), the first enz)Tne, ALA-synthetase, is found mainly in the mitochondria. The next four enzymes that convert ALA to coproporphyrinogen isomer III are localized in the cytosol that is, they are soluble enzymes. The last three enzymes are in the mitochondria—the two that oxidize, decarb-oxylate, and dehydrate coproporphyrinogen to protoporphyrinogen. 

Fig. 1. Heme biosynthetic pathway. Steps are catalyzed by 7, -aminolevulinic acid (ALA) synthetase 2, ALA dehydratase 3, uroporphyrinogen I synthetase (PBG deaminase) 4, uroporphyrinogen III cosynthetase 5, uroporphyrinogen decarboxylase 6, coproporphyrinogen oxidase 7, protoporphyrinogen oxidase and 8, ferrochelatase (heme synthetase)...

---