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Entry M0181    3.11.1.1    phosphonoacetaldehyde hydrolase

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Step 05

Lys53 initiates a double bond rearrangement that causes the reduction of the C=C in the alkylated intermediate and deprotonates water. The activated water attacks the phosphate in a nucleophilic substitution that releases Asp12 and the phosphate product.

GIF of Reaction Step M0181.stg05


Comment: Although reference [2] separates this step into a protonation of the C=C and cleavage by HO- of the aspartate phosphate bond, we are assuming that both species originate from the same water molecule and thus the reactions are concerted.



Mechanisms

Proton Transfer
Bimolecular Nucleophilic Substitution

Mechanism Components

Overall Reactant Used
Bond Formation
Bond Cleavage
Enzyme-Substrate Bond Cleavage
Bond Order Change
Intermediate Collapse
Intermediate Formation
Overall Product Formed

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
His56 Side Chain spectator Hydrogen Bond Acceptor
Hydrogen Bond Donor
Ala45 Main Chain Carbonyl spectator Hydrogen Bond Acceptor
Met49 Side Chain spectator Hydrogen Bond Acceptor
Arg160 Side Chain spectator Hydrogen Bond Donor
Electrostatic Stabiliser
Asp12 Side Chain reactant Hydrogen Bond Acceptor
Metal Ligand
Nucleofuge
Lys53 Side Chain reactant Covalently Attached
Nucleophile
Two Electron Donor

Metal Cofactors involved in Step 05

Metal Type Metal Identity Chain Activity Function
magnesium MG 502 x spectator Substrate Binding
Electrostatic Stabiliser
Increase Electrophilicity
Activator

Reactive Centre

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

View similar reactions in MACiE.


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