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Literature summary for 1.7.2.2 extracted from

  • Shaw, S.; Lukoyanov, D.; Danyal, K.; Dean, D.R.; Hoffman, B.M.; Seefeldt, L.C.
    Nitrite and hydroxylamine as nitrogenase substrates mechanistic implications for the pathway of N2 reduction (2014), J. Am. Chem. Soc., 136, 12776-12783 .
    View publication on PubMedView publication on EuropePMC

Metals/Ions

Metals/Ions Comment Organism Structure
Fe2+ initial and final states contain Fe(II) heme, catalytic heme in the Fe2+ state Azotobacter vinelandii

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
hydroxylamine + ferrocytochrome c Azotobacter vinelandii cf. EC 1.7.99.1 NH3 + H2O + ferricytochrome c
-
?
nitrite + 4 ferrocytochrome c + 5 H+ Azotobacter vinelandii cf. EC 1.7.2.6 hydroxylamine + H2O + 4 ferricytochrome c
-
?

Organism

Organism UniProt Comment Textmining
Azotobacter vinelandii
-
several strains
-

Reaction

Reaction Comment Organism Reaction ID
NH3 + 2 H2O + 6 ferricytochrome c = nitrite + 6 ferrocytochrome c + 7 H+ reaction mechanism, overview. NO2- binds to the enzyme ccNIR catalytic heme in the Fe2+ state, accepts two protons, and releases H2O to form a moiety formally written as Fe(II)-[NO+]. The key mechanistic challenge in reducing NO2- is to avoid or overcome formation of the terminal Fe(II)-NO thermodynamic sink through one-electron reduction of Fe(II)-[NO+]. Enzyme ccNIR achieves this by two proton-coupled electron transfer reductions that promptly reduce Fe(II)-[NO+] to Fe(II)-[HNO]. The process involves recharging of the catalytic heme with electrons obtained through transfer from the other hemes of the enzyme and of the heme environment with protons Azotobacter vinelandii

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
hydroxylamine + ferrocytochrome c cf. EC 1.7.99.1 Azotobacter vinelandii NH3 + H2O + ferricytochrome c
-
?
nitrite + 4 ferrocytochrome c + 5 H+ cf. EC 1.7.2.6 Azotobacter vinelandii hydroxylamine + H2O + 4 ferricytochrome c
-
?

Synonyms

Synonyms Comment Organism
ccNiR
-
Azotobacter vinelandii
multiheme cytochrome c nitrite reductase
-
Azotobacter vinelandii

Cofactor

Cofactor Comment Organism Structure
cytochrome c heme Azotobacter vinelandii
heme catalytic heme in the Fe2+ state Azotobacter vinelandii

General Information

General Information Comment Organism
additional information comparison of reaction mechanisms of nitrogenase, EC 1.18.6.1, and multiheme cytochrome c nitrite reductase, ccNIR, EC 1.7.2.2, overview Azotobacter vinelandii