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Entry M0262    4.2.3.6    trichodiene synthase

Previous Step

Step 06

The Pyrophosphate deprotonates the substrate, which initiates the first methyl migration, followed by a second methyl migration and finally a 1,4-hydride shift.

GIF of Reaction Step M0262.stg06


Comment: Leu97 appears to sterically hinder to potentially competing C12 or C13 methyl migrations. Thr96 sterically directs the C12 to C7 methyl migration. This final carbocation is quenched by proton elimination from C12, possibliy mediated by the carboxylate of Asp100 or the pyrophosphate. The pyrophosphate is shown here [4].



Mechanisms

Proton Transfer
Intramolecular Rearrangement

Mechanism Components

Bond Formation
Bond Cleavage
Bond Order Change
Intermediate Terminated
Overall Product Formed
Enzyme Regenerated

Amino acids involved in the reaction step.

Amino Acid Location of Function Activity Function
Tyr93 Side Chain spectator van der Waals interaction
Leu97 Side Chain spectator van der Waals interaction
Steric Role
Thr96 Side Chain spectator van der Waals interaction
Steric Role
Asp100 Side Chain spectator Metal Ligand
Electrostatic Stabiliser
Arg182 Side Chain spectator Electrostatic Stabiliser
Hydrogen Bond Donor
Lys232 Side Chain spectator Electrostatic Stabiliser
Hydrogen Bond Donor
Arg304 Side Chain spectator Electrostatic Stabiliser
Hydrogen Bond Donor
Tyr305 Side Chain spectator Electrostatic Stabiliser
Hydrogen Bond Donor

Metal Cofactors involved in Step 06

Metal Type Metal Identity Chain Activity Function
magnesium MG 701 B spectator Substrate Binding
Electrostatic Stabiliser
magnesium MG 702 B spectator Substrate Binding
Electrostatic Stabiliser
magnesium MG 703 B spectator Substrate Binding
Electrostatic Stabiliser

Reactive Centre

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

View similar reactions in MACiE.


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