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Literature summary for 1.18.6.1 extracted from

  • Dilworth, M.J.; Fisher, K.; Kim, C.H.; Newton, W.E.
    Effects on substrate reduction of substitution of histidine-195 by glutamine in the alpha-subunit of the MoFe protein of Azotobacter vinelandii nitrogenase (1998), Biochemistry, 37, 17495-17505.
    View publication on PubMed
Search for more literature for 1.18.6.1

Protein Variants

Protein Variants Comment Organism
H195Q below 2% N2 reducing activity remaining compared to wild-type due to less effective N2 binding Azotobacter vinelandii

Inhibitors

Inhibitors Comment Organism Structure
N2 inhibits C2H2 reduction of mutant H195Q; maximal inhibition of H2 production at Fe protein to MoFe protein ration 2.5 Azotobacter vinelandii
N3- inhibits H2 production competitively and reversibly Azotobacter vinelandii

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
 additional information
-
 Azotobacter vinelandii

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ Mg2+ required for MgATP complex Azotobacter vinelandii

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
8 reduced ferredoxin + 8 H+ + N2 + 16 ATP + 16 H2O Azotobacter vinelandii
-
 8 oxidized ferredoxin + H2 + 2 NH3 + 16 ADP + 16 phosphate
-
 ?

Organism

Organism UniProt Comment Textmining
Azotobacter vinelandii
-
-
-

Purification (Commentary)

Purification (Comment) Organism
wild-type and mutant H195Q Azotobacter vinelandii

Reaction

Reaction Comment Organism Reaction ID
4 reduced ferredoxin + 8 H+ + N2 + 16 ATP + 16 H2O = 4 oxidized ferredoxin + H2 + 2 NH3 + 16 ADP + 16 phosphate enzyme is composed of 2 metalloproteins: component I MoFe protein and component II Fe protein Azotobacter vinelandii
a

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
additional information
-
 assay in anaerobic atmosphere required Azotobacter vinelandii
0.024
-
 purified mutant H195Q enzyme, anaerobic atmosphere Azotobacter vinelandii
0.7
-
 purified enzyme, anaerobic atmosphere Azotobacter vinelandii

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
8 reduced ferredoxin + 8 H+ + N2 + 16 ATP + 16 H2O
-
 Azotobacter vinelandii 8 oxidized ferredoxin + H2 + 2 NH3 + 16 ADP + 16 phosphate
-
 ?
reduced ferredoxin + H+ + ATP
-
 Azotobacter vinelandii oxidized ferredoxin + H2 + ADP + phosphate
-
 ?
reduced ferredoxin + H+ + N3- + ATP mutant H195Q shows only about 7.5% activity compared to wild-type Azotobacter vinelandii oxidized ferredoxin + NH3 + N2 + ADP + phosphate
-
 ?

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
additional information
-
-
 Azotobacter vinelandii

Temperature Range [°C]

Temperature Minimum [°C] Temperature Maximum [°C] Comment Organism
13 45
-
 Azotobacter vinelandii

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
additional information
-
 additional information
-
 Azotobacter vinelandii