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Entry M0004    1.7.2.1    nitrite reductase (NO-forming)

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Step 02

Cu502 donates the electron to the bound nitrous acid, which collapses to form water, deprotonating His255B, and a Cu-bound NO radical.

It is unknown whether this reaction is reversible or not.

GIF of Reaction Step M0004.stg02


Comment: Water displaces the product C00533 after this step. An alternative role for His255 in this step may be to provide a positive charge in a location that assists in stabilising the transient complex of NO and water bound to the copper [1].



Mechanisms

Radical Formation
Redox
Elimination Reaction
Proton Transfer
Heterolysis

Mechanism Components

Bond Formation
Bond Cleavage
Overall Product Formed
Dehydration
Metal De-coordination

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Asp98A Side Chain spectator Hydrogen Bond Acceptor
His135A Side Chain spectator Metal Ligand
His135A Main Chain Carbonyl spectator Not Active
Cys136A Side Chain spectator Metal Ligand
Cys136A Main Chain Amide spectator Not Active
His255B Side Chain reactant Proton Donor
Hydrogen Bond Donor

Metal Cofactors involved in Step 02

Metal Type Metal Identity Chain Activity Function
copper CU 501 A spectator Not Active
copper CU 502 A reactant Substrate Binding
One Electron Donor

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
O-H
Cu-O
N-H
N-O
None
Cu
H
N
O

View similar reactions in MACiE.


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