Editing Nitrite (section)

==Biochemistry==
[[File:Nitrogen Cycle - Reactions and Enzymes.svg|thumb|upright=1.5|class=skin-invert-image|A schematic representation of the microbial nitrogen cycle.<ref>{{Cite journal|last1=Sparacino-Watkins|first1=Courtney|last2=Stolz|first2=John F.|last3=Basu|first3=Partha|date=2013-12-16|title=Nitrate and periplasmic nitrate reductases|journal=Chem. Soc. Rev.|language=en|volume=43|issue=2|pages=676–706|doi=10.1039/c3cs60249d|pmid=24141308|issn=1460-4744|pmc=4080430}}</ref><ref>{{Cite journal|last1=Simon|first1=Jörg|last2=Klotz|first2=Martin G.|title=Diversity and evolution of bioenergetic systems involved in microbial nitrogen compound transformations|journal=Biochimica et Biophysica Acta (BBA) - Bioenergetics|language=en|volume=1827|issue=2|pages=114–135|doi=10.1016/j.bbabio.2012.07.005|pmid=22842521|year=2013|doi-access=free}}</ref> [[Anammox|ANAMMOX]] is anaerobic ammonium oxidation, [[Dissimilatory nitrate reduction to ammonium|DNRA]] is dissimilatory nitrate reduction to ammonium, and [[Comammox|COMMAMOX]] is complete ammonium oxidation.]]

In [[nitrification]], [[ammonium]] is converted to nitrite.  Important species include ''[[Nitrosomonas]]''. Other bacterial species such as ''[[Nitrobacter]]'', are responsible for the oxidation of the nitrite into nitrate.

Nitrite can be reduced to [[nitric oxide]] or [[ammonia]] by many species of bacteria. Under hypoxic conditions, nitrite may release nitric oxide, which causes potent [[vasodilation]]. Several mechanisms for nitrite conversion to NO have been described, including enzymatic reduction by [[xanthine oxidoreductase]], [[nitrite reductase]], and [[Nitric oxide synthase|NO synthase]] (NOS), as well as nonenzymatic acidic [[disproportionation]] reactions.