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Entry M0251    2.1.1.63    methylated-DNA--[protein]-cysteine S-methyltransferase

Step 01

His146 deprotonates water, which in turn deprotonates Cys145. Cys145 then initiates a nucleophilic attack upon the methylated DNA in a substitution reaction. The DNA base then undergoes double bond rearrangement, resulting in the deprotonation of Tyr114.

Rate Determining Step

This reaction is irreversible.

GIF of Reaction Step M0251.stg01



Mechanisms

Proton Transfer
Bimolecular Nucleophilic Substitution

Mechanism Components

Bond Formation
Bond Cleavage
Bond Order Change
Proton Relay
Overall Reactant Used
Overall Product Formed
Enzyme Not Regenerated

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Glu172 Side Chain spectator Hydrogen Bond Acceptor
Increase Basicity
His146 Side Chain reactant Hydrogen Bond Donor
Hydrogen Bond Acceptor
Proton Acceptor
Cys145 Side Chain reactant Hydrogen Bond Donor
Proton Donor
Nucleophile
Asn137 Side Chain spectator Hydrogen Bond Donor
Hydrogen Bond Acceptor
Electrostatic Stabiliser
Tyr114 Side Chain reactant Hydrogen Bond Donor
Proton Donor

Reactive Centre

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

View similar reactions in MACiE.


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