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Entry M0143    1.20.4.1    arsenate reductase

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Step 02

Thiolate of Cys82 attacks the sulfur of Cys10 in a nucleophilic substitution reaction that releases the arsenite product, and creates a disulfide bond between Cys10 and Cys82.

GIF of Reaction Step M0143.stg02


Comment: The formation of the Cys10-Cys82 disulfide bond triggers the structural change that allows Cys89 to move out of its hydrophobic core, so that it can attack Cys82 [1].



Mechanisms

Bimolecular Nucleophilic Substitution

Mechanism Components

Bond Formation
Bond Cleavage
Enzyme-Substrate Bond Cleavage
Intermediate Terminated
Overall Product Formed
Cyclisation
Bond Order Change

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Cys10A Side Chain reactant Electrofuge
Hydrogen Bond Acceptor
Electrophile
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 Hydrogen Bond Donor
Electrostatic Stabiliser
Ser17 Side Chain spectator Hydrogen Bond Donor
Cys82 Side Chain reactant Nucleophile
Hydrogen Bond Acceptor
Cys89 Side Chain spectator Not Active
Asp105 Side Chain spectator Hydrogen Bond Acceptor

Metal Cofactors involved in Step 02

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
As-S
The As-O bond changes from a double to single bond
As
O
S

View similar reactions in MACiE.


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