Biology:Cytochrome c nitrite reductase
| Cytochrome c nitrite reductase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 Crystallographic structure of a homodimer of the cytochrome c nitrite reductase from Escherichia coli (rainbow colored cartoon, blue = N-terminus, red = C-terminus) complexed with heme C (sticks).[1] | |||||||||
| Identifiers | |||||||||
| EC number | 1.7.2.2 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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Cytochrome c nitrite reductase (ccNiR) (EC 1.7.2.2) is a bacterial enzyme that catalyzes the six electron reduction of nitrite to ammonia; an important step in the biological nitrogen cycle.[2] The enzyme catalyses the second step in the two step conversion of nitrate to ammonia, which allows certain bacteria to use nitrite as a terminal electron acceptor, rather than oxygen, during anaerobic conditions. During this process, ccNiR draws electrons from the quinol pool, which are ultimately provided by a dehydrogenase such as formate dehydrogenase or hydrogenase. These dehydrogenases are responsible for generating a proton motive force.[3]
Cytochrome c Nitrite Reductase is a homodimer which contains five c-type heme cofactors per monomer.[4] Four of the heme centers are bis-histidine ligated and presumably serve to shuttle electrons to the active site. The active site heme, however, is uniquely ligated by a single lysine residue.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with a cytochrome as acceptor. The systematic name of this enzyme class is ammonia:ferricytochrome-c oxidoreductase.
| Cytochrom_NNT | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Cytochrom_NNT | ||||||||
| Pfam | PF03264 | ||||||||
| Pfam clan | CL0317 | ||||||||
| InterPro | IPR005126 | ||||||||
| OPM superfamily | 175 | ||||||||
| OPM protein | 2j7a | ||||||||
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References
- ↑ PDB: 1GU6; "Structure and spectroscopy of the periplasmic cytochrome c nitrite reductase from Escherichia coli". Biochemistry 41 (9): 2921–31. March 2002. doi:10.1021/bi015765d. PMID 11863430.
- ↑ "Escherichia coli cytochrome c nitrite reductase NrfA". Meth. Enzymol.. Methods in Enzymology 437: 63–77. 2008. doi:10.1016/S0076-6879(07)37004-3. ISBN 9780123742780. PMID 18433623.
- ↑ Simon J (August 2002). "Enzymology and bioenergetics of respiratory nitrite ammonification". FEMS Microbiol. Rev. 26 (3): 285–309. doi:10.1111/j.1574-6976.2002.tb00616.x. PMID 12165429.
- ↑ "Structure of cytochrome c nitrite reductase". Nature 400 (6743): 476–80. July 1999. doi:10.1038/22802. PMID 10440380. Bibcode: 1999Natur.400..476E.
Further reading
- "Structure of cytochrome c nitrite reductase". Nature 400 (6743): 476–80. July 1999. doi:10.1038/22802. PMID 10440380. Bibcode: 1999Natur.400..476E.
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