spacer

Entry M0055    4.2.1.10    3-dehydroquinate dehydratase (type II)

Previous Step     Next Step

Step 02

Asn16 deprotonates water, which deprotonates the C1-hydroxy, causing a double bond rearrangement that eliminates water with deprotonation of His106, which in turn deprotonates Glu104.

GIF of Reaction Step M0055.stg02


Comment: His106 is the only residue appropriately positioned to act as the proton donor in this step. The OD2 of the invariant Asn79 is a hydrogen bond acceptor for the C1 hydroxy, thereby correctly orienting it to accept a proton. The driving force for the release of the product is the fact that there is not enough space in the active site for the water and product to be present together [2].



Mechanisms

Bimolecular Elimination
Proton Transfer

Mechanism Components

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

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Asn79 Side Chain spectator Hydrogen Bond Acceptor
Steric Role
Arg113 Side Chain spectator Polar Interaction
Electrostatic Stabiliser
His106 Side Chain reactant Proton Acceptor
Proton Donor
Hydrogen Bond Acceptor
Hydrogen Bond Donor
Pro15 Main Chain Carbonyl spectator Hydrogen Bond Acceptor
Steric Role
Activator
Asn16 Side Chain reactant Hydrogen Bond Acceptor
Proton Acceptor
Arg23 Side Chain spectator Polar Interaction
Electrostatic Stabiliser
Tyr28 Side Chain spectator Not Active
Ala82 Main Chain Amide spectator Hydrogen Bond Donor
Steric Role
Activator
Glu104 Side Chain reactant Proton Donor
Hydrogen Bond Donor

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
N-H
N-H
O-H
O-H
C-O
N-H
O-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-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.


spacer
spacer