Ferredoxin (from Azotobacter vinelandii)

 

The ferredoxin which can be isolated from bacteria that reduce nitrogen plays an important role as an electron transfer agent. It is only indirectly involved in nitrogen assimilation, which takes probably place at iron-sulfur clusters in nitrogenase.

This ferredoxin contains one 3Fe4S cluster and one 4Fe4S cluster.

 

  Coordination environment of iron in the 3Fe4S cluster

  Coordination environment of iron in the 4Fe4S cluster