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Literature summary for 1.7.1.3 extracted from

  • McDonald, D.W.; Coddington, A.
    Properties of the assimilatory nitrate reductase from Aspergillus nidulans (1974), Eur. J. Biochem., 46, 169-178.
    View publication on PubMed

Inhibitors

Inhibitors Comment Organism Structure
8-hydroxyquinoline pH 7.5, 20% inhibition at 0.1 mM Aspergillus nidulans
azide pH 7.5, 90% inhibition at 0.01 mM Aspergillus nidulans
cyanide pH 7.5, 100% inhibition at 0.01 mM Aspergillus nidulans
iodoacetamide pH 7.5, 40% inhibition at 1 mM Aspergillus nidulans
additional information cysteine or dithiothreitol relieve or prevent inhibition. Not inhibited by urea, glutamic acid, aspartic acid and ammonia at 10 mM Aspergillus nidulans
NADP+ inhibits NADPH oxidation, non-competitive with respect to nitrate Aspergillus nidulans
nitrite competitive with respect to nitrate and non-competitive to NADPH Aspergillus nidulans
p-hydroxymercuribenzoate pH 7.5, 85% inhibition at 0.001 mM Aspergillus nidulans
phenanthroline hydrate pH 7.5, 1:10, 20% inhibition at 0.1 mM Aspergillus nidulans
potassium chlorate pH 7.5, slight, 20% inhibition at 5 mM Aspergillus nidulans
Sodium nitrite pH 7.5, slight, 50% inhibition at 5 mM Aspergillus nidulans

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.009
-
NADPH + nitrate, pH 6.5 and + cytochrome c, pH 7.5 Aspergillus nidulans
0.01
-
NADPH + nitrate, pH 7.5 Aspergillus nidulans
0.015
-
NADPH + cytochrome c, pH 8.5 Aspergillus nidulans
0.024
-
cytochrome c cosubstrate NADPH, pH 8.5 Aspergillus nidulans
0.029
-
cytochrome c cosubstrate NADPH, pH 7.5 Aspergillus nidulans
0.06
-
nitrate cosubstrate NADPH, pH 7.5 Aspergillus nidulans
0.08
-
nitrate cosubstrate NADPH, pH 6.5 Aspergillus nidulans

Metals/Ions

Metals/Ions Comment Organism Structure
Molybdenum
-
Aspergillus nidulans
phosphate stimulates, required for maximal activity Aspergillus nidulans

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
180000 200000 sucrose density gradient, gel-filtration Aspergillus nidulans

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
nitrate + NADPH Aspergillus nidulans
-
nitrite + NADP+ + H2O
-
?

Organism

Organism UniProt Comment Textmining
Aspergillus nidulans
-
bi-1 a, translocation-free biotin auxotroph
-

Purification (Commentary)

Purification (Comment) Organism
ion-exchange, ammonium sulfate precipitation, gel filtration Aspergillus nidulans

Reaction

Reaction Comment Organism Reaction ID
nitrite + NADP+ + H2O = nitrate + NADPH + H+ random order rapid-equilibrium mechanism, two functional parts: 1. heat labile, FAD and haemoprotein containing, binds NADPH and transfers electrons from NADPH via FAD and perhaps cytochrome b to acceptors such as cytochrome c, 2. heat stable, molybdenum containing, accepts electrons from reduced viologen dyes and transfers them to nitrate Aspergillus nidulans

Specific Activity [micromol/min/mg]

Specific Activity Minimum [┬Ámol/min/mg] Specific Activity Maximum [┬Ámol/min/mg] Comment Organism
2.5
-
-
Aspergillus nidulans
4 16.1 at different stages of purification Aspergillus nidulans

Storage Stability

Storage Stability Organism
4┬░C, half life of 3-5 days Aspergillus nidulans

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
chlorate + NADPH lower affinity than to nitrate, appears to be toxic or its product Aspergillus nidulans chlorite + NADP+
-
?
ferricytochrome c + NADPH + H+
-
Aspergillus nidulans ferrocytochrome c + NADP+ + H2O
-
r
nitrate + NADPH
-
Aspergillus nidulans nitrite + NADP+ + H2O
-
?
nitrate + NADPH two associated activities: cytochrome c reductase and reduced viologen dye:nitrate reductase Aspergillus nidulans nitrite + NADP+ + H2O
-
?

Temperature Optimum [┬░C]

Temperature Optimum [┬░C] Temperature Optimum Maximum [┬░C] Comment Organism
25
-
assay at Aspergillus nidulans

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.5
-
assay at Aspergillus nidulans
7.5 8
-
Aspergillus nidulans

Cofactor

Cofactor Comment Organism Structure
FAD stimulated by flavin Aspergillus nidulans
heme
-
Aspergillus nidulans

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.04 0.048 NADP+ NADPH as substrate in saturating and non-saturating concentrations, competitive Aspergillus nidulans
0.065
-
NADP+ nitrate as substrate in non-saturating concentrations, non-competitive Aspergillus nidulans
0.15
-
nitrite NADPH as substrate in non-saturation concentration, non-competitive Aspergillus nidulans
0.18
-
nitrite nitrate as substrate in saturating and non-saturating concentrations, competitive Aspergillus nidulans