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Entry M0128    1.13.12.7    photinus-luciferin 4-monooxygenase

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Step 02

Water deprotonates the luciferin intermediate at the C4 atom resulting in a carbanionic intermediate

Rate Determining Step

GIF of Reaction Step M0128.stg02


Comment: This step occurs in the bAcs Conformation. To oxidise luciferin, luciferase must abstract the C4 proton producing a carbanion that undergoes electrophilic attack by molecular oxygen. This process is greatly facilitated by the activating effect of AMP which increases the acidity of C4 and is a good leaving group, allowing the formation of the dioxetanone ring. The abstraction of the proton from C4 is the rate-limiting step of the oxygenase reaction [3]. Due to lack of evidence suggesting an enzymatic base we have assumed that the base is water.



Mechanisms

Proton Transfer

Mechanism Components

Bond Formation
Bond Cleavage
Intermediate Formation

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Thr343A Side Chain spectator Hydrogen Bond Donor
Thr343A Main Chain Amide spectator Hydrogen Bond Donor
Lys443 Side Chain spectator Hydrogen Bond Donor
Electrostatic Stabiliser

Metal Cofactors involved in Step 02

Metal Type Metal Identity Chain Activity Function
magnesium MG(not in PDB) 1 x spectator Not Active

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
O-H
C-H
None
C
H
O

View similar reactions in MACiE.


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