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Entry M0237    1.5.1.33    pteridine reductase

Previous Step

Step 03

NADPH transfers a hydride to the C6 position of the dihydrobiopterin intermediate. The N5 position is protonated by an activated water. This water then deprotonates the 4-hydroxyl group and causes tautomerisation back to the keto-form.

GIF of Reaction Step M0237.stg03


Comment: The water molecule is activated by interacting with the 4-hydroxyl group of dihydrobiopterin.



Mechanisms

Hydride Transfer
Bimolecular Nucleophilic Addition
Proton Transfer
Assisted Keto-Enol Tautomerisation

Mechanism Components

Bond Cleavage
Bond Formation
Bond Order Change
Bond Polarisation
Enzyme Regenerated
Intermediate Terminated
Overall Product Formed
Proton Relay
Overall Reactant Used

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Arg14 Side Chain spectator Electrostatic Stabiliser
Hydrogen Bond Donor
Steric Role
Asp161 Side Chain spectator Hydrogen Bond Donor
Hydrogen Bond Acceptor
Tyr174 Side Chain spectator Hydrogen Bond Donor

Reactive Centre

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

View similar reactions in MACiE.


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