|Gene:||nit-6||Accession Number: G-9620 (MetaCyc)|
Synonyms: NAD(P)H-nitrite reductase, nitrite reductase [NAD(P)H]
Species: Neurospora crassa
Subunit composition of
assimilatory nitrite reductase = [Nit-6]2
nitrite reductase subunit = Nit-6
Nitrite reductase from Neurospora crassa shows significant amino acid sequence homology with the enzymes from Escherichia coli and Aspergillus nidulans FGSC A4 [Exley93]. The enzyme contains siroheme, non-heme iron in iron-sulfur clusters, and FAD [Prodouz81].
The native molecular weight was determined by gel filtration chromatography and sucrose density gradient centrifugation [Lafferty74].
The subunit molecular weight was determined by SDS-PAGE. The isoelectric point determined for the monomeric subunit was 6.8-6.9 [Prodouz81].
Molecular Weight of Polypeptide: 127.37 kD (from nucleotide sequence), 140 kD (experimental) [Prodouz81 ]
Molecular Weight of Multimer: 290 kD (experimental) [Lafferty74]
Relationship Links: Entrez-Nucleotide:PART-OF:L07391 , InterPro:IN-FAMILY:IPR001327 , InterPro:IN-FAMILY:IPR005117 , InterPro:IN-FAMILY:IPR006066 , InterPro:IN-FAMILY:IPR006067 , InterPro:IN-FAMILY:IPR007419 , InterPro:IN-FAMILY:IPR012744 , InterPro:IN-FAMILY:IPR013027 , InterPro:IN-FAMILY:IPR017941 , InterPro:IN-FAMILY:IPR023753 , Pfam:IN-FAMILY:PF00070 , Pfam:IN-FAMILY:PF00355 , Pfam:IN-FAMILY:PF01077 , Pfam:IN-FAMILY:PF03460 , Pfam:IN-FAMILY:PF04324 , Pfam:IN-FAMILY:PF07992 , Prints:IN-FAMILY:PR00368 , Prints:IN-FAMILY:PR00397 , Prosite:IN-FAMILY:PS00365 , Prosite:IN-FAMILY:PS51296
Instance reaction of [ammonium + 3 NAD(P)+ + 2 H2O ← nitrite + 3 NAD(P)H + 5 H+] (220.127.116.11):
Enzymatic reaction of: nitrite reductase
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the opposite direction.
This enzyme catalyzes the reduction of nitrite to ammonia in a NADPH-dependent, six-electron transfer reaction. The siroheme prosthetic group is involved in the catalysis and may bind nitrite. NADH can replace NADPH as an electron donor, but NADPH is preferred [Greenbaum78]. Inhibition of the enzyme by carbon monoxide requires the presence of NADPH, and is not complete unless FAD is added [Vega75].
pH(opt): 7.5 [Lafferty74]
Exley93: Exley GE, Colandene JD, Garrett RH (1993). "Molecular cloning, characterization, and nucleotide sequence of nit-6, the structural gene for nitrite reductase in Neurospora crassa." J Bacteriol 175(8);2379-92. PMID: 8096840
Greenbaum78: Greenbaum P, Prodouz KN, Garrett RH (1978). "Preparation and some properties of homogeneous Neurospora crassa assimilatory NADPH-nitrite reductase." Biochim Biophys Acta 526(1);52-64. PMID: 150863
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