TCDB is operated by the Saier Lab Bioinformatics Group
« See all members of the family

Nitric oxide reductase (EC # (NorBC) (component of the anerobic, respiratory chain that converts NO3- to N2; denitrification) [reaction catalyzed by Nor: 2 nitric oxide (NO) + 2e- + 2H+ → nitrous oxide (N20) + H2O].  This enzyme does not pump protons across the bacterial membrane (Reimann et al. 2007), but the protons needed for the reaction are taken from the periplasmic side of the membrane (from which side the electrons are donated). P. denitrificans NOR uses a single defined proton pathway with residues Glu-58 and Lys-54 from the NorC subunit at the entrance (ter Beek et al. 2016).  norC and norB encode the cytochrome-c-containing subunit II and cytochrome b-containing subunit I of nitric-oxide reductase (NO reductase), respectively. norQ encodes a protein with an ATP-binding motif and is similar to NirQ from Pseudomonas stutzeri and Pseudomonas aeruginosa and CbbQ from Pseudomonas hydrogenothermophila. norE encodes a protein with five putative transmembrane alpha-helices and has similarity to CoxIII, the third subunit of the aa3-type cytochrome-c oxidases. norF encodes a small protein with two putative transmembrane alpha-helices. Mutagenesis of norC, norB, norQ or norD resulted in cells unable to grow anaerobically. Nitrite reductase and NO reductase (with succinate or ascorbate as substrates) and nitrous oxide reductase (with succinate as substrate) activities were not detected in these mutant strains. Nitrite extrusion was detected in the medium, indicating that nitrate reductase was active. The norQ and norD mutant strains retained about 16% and 23% of the wild-type level of NorC, respectively. The norE and norF mutant strains had specific growth rates and NorC contents similar to those of the wild-type strain, but had reduced NOR and NIR activities, indicating that their gene products are involved in regulation of enzyme activity (de Boer et al. 1996).

Accession Number:Q51662
Protein Name:NorC aka Nitric-oxide reductase subunit C
Molecular Weight:16992.00
Species:Paracoccus denitrificans [266]
Number of TMSs:1
Location1 / Topology2 / Orientation3: Cell membrane1 / Single-pass membrane protein2
Substrate H+

Cross database links:

RefSeq: YP_916267.1   
Entrez Gene ID: 4580122   
Pfam: PF00034   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0070469 C:respiratory chain
GO:0009055 F:electron carrier activity
GO:0020037 F:heme binding
GO:0022900 P:electron transport chain
GO:0006810 P:transport

References (2)

[1] “Mutational analysis of the nor gene cluster which encodes nitric-oxide reductase from Paracoccus denitrificans.”  de Boer   9022686
[2] “The active site of the bacterial nitric oxide reductase is a dinuclear iron center.”  Hendriks   9748316

External Searches:

  • Search: DB with
  • BLAST ExPASy (Swiss Institute of Bioinformatics (SIB) BLAST)
  • CDD Search (Conserved Domain Database)
  • Search COGs (Clusters of Orthologous Groups of proteins)
  • 2° Structure (Network Protein Sequence Analysis)


Predict TMSs (Predict number of transmembrane segments)
Window Size: Angle:  
Window Size: Angle:  
FASTA formatted sequence