In enzymology, a ferredoxinâÂÂnitrite reductase () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are NH<sub>3</sub>, H<sub>2</sub>O, and oxidized ferredoxin, whereas its 3 products are nitrite, reduced ferredoxin, and H<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with an iron-sulfur protein as acceptor. The systematic name of this enzyme class is ammonia:ferredoxin oxidoreductase. This enzyme participates in nitrogen metabolism and nitrogen assimilation. It has 3 cofactors: iron, Siroheme, and Iron-sulfur.
This enzyme can use many different isoforms of ferredoxin. In photosynthesizing tissues, it uses ferredoxin that is reduced by PSI and in the root it uses a form of ferredoxin (FdIII) that has a less negative midpoint potential and can be reduced easily by NADPH.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .