Ferrochelatase !

Ferrochelatase puts iron inside protoporphyrin and finishes heme synthesis in the mitochondrion.

Updated 2026-11-01

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Key facts

Protoporphyrin IX + Fe²⁺ → heme + 2 H⁺, on the matrix side of the mitochondrial inner membrane.
It is a dimer with one [2Fe-2S] cluster per subunit; structure 2QD3 holds the product, heme, in the active site.
When iron is short it inserts zinc: zinc protoporphyrin forms.
Lead inhibits it, along with ALA dehydratase.

It depends on iron delivered to the mitochondrion (mitoferrin) and forms a complex with other late-pathway enzymes.

Erythropoietic protoporphyria: nearly always a null FECH allele plus a low-expression variant on the other allele.
Free protoporphyrin builds up in red cells and skin (burning pain in sunlight) and is excreted in bile (gallstones, liver damage).
High red-cell zinc protoporphyrin: iron deficiency or lead poisoning; high free (metal-free) protoporphyrin: protoporphyria.

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What does ferrochelatase do, and where?

It inserts Fe²⁺ into protoporphyrin IX to form heme, in the mitochondrion.

What forms when ferrochelatase has no iron available?

Zinc protoporphyrin: the enzyme inserts zinc instead of iron.

Which disease does ferrochelatase deficiency cause?

Erythropoietic protoporphyria, with burning skin pain minutes after sun exposure.

Educational information, not medical advice. For any symptom, see a health professional.

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Representative model, for educational purposes only.