2Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, 119991 Moscow, Russia; fax: (495) 135-1405
3Russian National Research Center “Kurchatov Institute”, pl. Kurchatova 1, 123182 Moscow, Russia; fax: (499) 196-1704; E-mail: email@example.com
* To whom correspondence should be addressed.
Received June 8, 2012; Revision received June 22, 2012
Octaheme oxidoreductases are widespread among various bacterial taxa involved in the biogeochemical nitrogen cycle. The evolution of octaheme oxidoreductases of the nitrogen cycle from the evolutionarily more ancient pentaheme nitrite reductases was accompanied by changes in function from reduction of nitrogen oxides to their oxidation under changing environmental conditions. Octaheme nitrite reductases, which are the subject of the present review, are of a transitional form that combines structural and functional characteristics of pentaheme reductases and octaheme oxidases and possesses a number of unique features typical of only this family of enzymes. The review summarizes data on structure–function investigations of the family of octaheme nitrite reductases. Emphasis is given to comparison of the structures and functions of octaheme nitrite reductases and other multiheme oxidoreductases of the nitrogen cycle.
KEY WORDS: multiheme cytochrome c, octaheme nitrite reductase, structure, properties, evolution