spacer

Entry M0131    1.14.13.2    4-hydroxybenzoate 3-monooxygenase

Previous Step     Next Step

Step 08

Water deprotonates the 3,4-dihydroxybenzoic acid through the His72-water-water-Tyr385-Tyr201 proton transfer chain.

GIF of Reaction Step M0131.stg08


Comment: Product deprotonation enhances the rate of a specific conformational change required for both product release and the elimination of water from flavin-C4a-hydroxide. The 3-hydroxyl of the product can form a strong H-bond with the backbone carbonyl of Pro293. This interaction probably prevents the product, which should be more reactive than the substrate, from exposing its 5-carbon to attack in subsequent cycles of catalysis and inhibits formation of the out conformation for enzyme reduction in the presence of product. Pro293 is also known to be fundamental to the conformational response of the protein to signals from the substrate pOHB [2].



Mechanisms

Proton Transfer

Mechanism Components

Bond Formation
Bond Cleavage
Bond Order Change
Intermediate Terminated
Overall Product Formed
Proton Relay

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
His72 Side Chain reactant Hydrogen Bond Acceptor
Hydrogen Bond Donor
Proton Acceptor
Proton Donor
Proton Relay
Tyr201 Side Chain reactant Hydrogen Bond Donor
Hydrogen Bond Acceptor
Proton Acceptor
Proton Donor
Proton Relay
Tyr385 Side Chain reactant Hydrogen Bond Donor
Hydrogen Bond Acceptor
Proton Acceptor
Proton Donor
Proton Relay
Pro293 Main Chain Carbonyl spectator Hydrogen Bond Acceptor
Lys297 Side Chain spectator Steric Role

Organic Cofactors involved in the reaction step

Cofactor Type Cofactor Activity Function
FAD FAD395 reactant Covalently Attached

Reactive Centre

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

View similar reactions in MACiE.


spacer
spacer