Structure and mechanism of iron and magnesium chelatases - at the heme-chlorophyll branch-point
Tetrapyrroles are synthesised through a single branched biosynthetic pathway. Heme and chlorophyll are synthesised from the common intermediate protoporphyrin IX at the heme-chlorophyll branch-point. Ferrochelatase catalyses the synthesis of heme by inserting Fe(II) into the protoporphyrin macro-cycle while magnesium chelatase, a three-subunit enzyme, catalyses the first unique step in chlorophyll