Iron enters the body in two forms: nonheme iron and heme iron.

During the detection of diatomic gases, the binding of the gas ligand to the heme iron induces conformational changes in the surrounding protein.

Abiterone binds in the active site of the enzyme and coordinates the heme iron through its pyridine nitrogen, mimicking the subtrate.

The heme iron serves as a source or sink of electrons during electron transfer or redox chemistry.

In the transportation or detection of diatomic gases, the gas binds to the heme iron.

Iron in meat (heme iron) is more easily absorbed than iron in vegetables.

The heme iron is ligated to histidine residue (His-59).

The heme is positioned between β-sheet and an α-helix, with heme iron ligated to cysteinate residue.

The reductase domain supplies an electron to the heme iron to achieve a high rate of catalytic NO dioxygenation.

Molecular oxygen binds covalently to the distal axial coordination position of the heme iron.