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Entry M0143    1.20.4.1    arsenate reductase

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Step 04

The disulfide bond between Cys82 and Cys89 is transferred to Cys82 and the thioredoxin acceptor in a nucleophilic substitution reaction that releases Cys89.

GIF of Reaction Step M0143.stg04


Comment: It is unclear which sulfur initiates the reaction. It is also unclear whether the nucleophilic cysteine residue from the thioredoxin attacks the Cys82 or the Cys89 of the enzyme. We assume thioredoxin attacks Cys82.



Mechanisms

Bimolecular Nucleophilic Substitution

Mechanism Components

Overall Reactant Used
Bond Formation
Enzyme-Substrate Bond Formation
Bond Cleavage
Intermediate Formation
Decyclisation

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Cys10A Side Chain spectator Hydrogen Bond Acceptor
Cys10A Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Thr11 Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Gly12 Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Asn13 Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Ser14 Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Cys15 Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Arg16A Main Chain Amide spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Arg16A Side Chain spectator Not Active
Ser17 Side Chain spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Cys82 Side Chain reactant Electrophile
Electrofuge
Cys89 Side Chain reactant Nucleofuge
Asp105 Side Chain spectator Not Active

Metal Cofactors involved in Step 04

Metal Type Metal Identity Chain Activity Function
potassium K 133 _ spectator Active site structural component

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
S-S
S-S
None
S

View similar reactions in MACiE.


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