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Entry M0276    1.7.99.4    nitrate reductase

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Step 04

A solvent molecule acts as a proton donor to the dianionic molybdenum centre.

GIF of Reaction Step M0276.stg04


Comment: The proton donor is presumed to be a solvent molecule because of the identification of solvent channels close to the metal coordination site. However, the possibility of a residue acting as a general acid has not been ruled out [1].



Mechanisms

Proton Transfer

Mechanism Components

Bond Cleavage
Bond Formation
Intermediate Formation
Bond Order Change
Overall Reactant Used

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Met153A Side Chain spectator Electrostatic Stabiliser
Polar Non-polar interaction
Steric Role
Lys56A Side Chain spectator Hydrogen Bond Donor
Cys152 Side Chain reactant Activator
Electrostatic Stabiliser
Metal Ligand
Covalently Attached
Gly383A Main Chain Amide spectator Hydrogen Bond Donor
Met346A Side Chain spectator Electrostatic Stabiliser
Polar Non-polar interaction
Steric Role
Glu384A Side Chain spectator Not Active

Organic Cofactors involved in the reaction step

Cofactor Type Cofactor Activity Function
Molybdopterin guanosine dinucleotide MGD1803A spectator Electrostatic Stabiliser
Metal Ligand
Molybdopterin guanosine dinucleotide MGD1804A spectator Electrostatic Stabiliser
Metal Ligand

Metal Cofactors involved in Step 04

Metal Type Metal Identity Chain Activity Function
iron SF4 1801 A spectator Not Active
molybdenum MO 1802 A spectator Not Active
iron HEC 1128 B spectator Not Active
iron HEC 1129 B spectator Not Active

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
O-H
O-H
The Mo-O bond changes from a double to single bond
H
Mo
O

View similar reactions in MACiE.


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