[1] The structures of chorismate mutases vary in different organisms, but the majority belong to the AroQ family and are characterized by an intertwined homodimer of 3-helical subunits.

The mechanism for this transformation is formally a Claisen rearrangement, supported by the kinetic and isotopic data reported by Knowles, et al.[7] E. coli and Yeast chorismate mutase have a limited sequence homology, but their active sites contain similar residues.

Evidence for this conformation is provided by an inverse secondary kinetic isotope effect at the carbon directly attached to the hydroxyl group.

[6] This seemingly unfavorable arrangement is achieved through a series of electrostatic interactions, which rotate the extended chain of chorismate into the conformation required for this concerted mechanism.

Not only does this stabilize the complex, but disruption of resonance within the vinyl ether destabilizes the ground state and reduces the energy barrier for this transformation.

[8] This is shown in mutants of the native enzyme in which Arg90 is replaced with citrulline to demonstrate the importance of hydrogen bonding to stabilize the transition state.

[9] Other work using chorismate mutase from Bacillus subtilis showed evidence that when a cation was aptly placed in the active site, the electrostatic interactions between it and the negatively charged transition state promoted catalysis.

However, the relative contribution of conformational constraint of the flexible substrate, specific hydrogen bonding to the transition state, and electrostatic interactions to the observed rate enhancement is still under discussion.