How many ligands does Fe has in heme ? I am not sure how many are in heme and how many in cytochrome C. Its about iron complexes.

  • $\begingroup$ Sorry. Check the answer again. $\endgroup$
    – rch
    Jul 19 '14 at 23:08

Heme: The Iron molecule is bound to 4 Nitrogen atoms, but take a look at porphyrin. All the nitrogens are part of one actual structure. You can visualize the iron molecule in the center of the larger compound's structure, replacing the two Hydrogen atoms in N-H:

The large structure surrounding and coordinating with Fe is also known as a polydentate ligand since it bonds to Iron at more than one site. So there is just one ligand on Fe.

porphyrin enter image description here

Cytochrome C: is a heme protein, so you may expect the same answer: A single polydentate ligand binds to Iron. This page has a PDB Model of it in a plugin.

As one ligand coordinates to four sites in this case, other ligands typically attach (e.g. oxygen binding in hemoglobin) to fill the octahedral group (up to 6 ligands attached to Fe the coordinate center).


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