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Entry M0267    4.2.1.52    dihydrodipicolinate synthase

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Step 07

A 6-exo-tet cyclisation (Baldwin's classification) occurs in the enzyme-substrate intermediate.

GIF of Reaction Step M0267.stg07


Comment: Dobson et al. [2] have suggested that the cyclisation process may occur outside of the active site and that once addition has occurred, hydrolysis breaks the enzyme-substrate bond and the acyclic intermediate leaves the active site. In this alternative mechanism, the hydrolytic water is activated by the carbonyl backbone of Ile203



Mechanisms

Intramolecular Nucleophilic Addition

Mechanism Components

Cyclisation
Bond Formation
Bond Order Change
Intermediate Formation

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Lys161 Side Chain reactant Covalently Attached
Two Electron Acceptor
Ile203 Main Chain Carbonyl spectator Activator
Steric Role
Tyr133 Side Chain spectator Not Active

Reactive Centre

Bonds Formed Bonds Cleaved Bonds Changed in Order Atom Types Involved
C-N
None
The C-N bond changes from a double to single bond
C
N

View similar reactions in MACiE.


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