Substrate Conformational Transition and the Role of Active Site Residues

Substrate Conformational Transition and the Role of Active Site Residues 

82] showed that the reactive CHAIR conformer is considerably less stable than other pseudodiaxial and pseudodiequatorial conformers (see Table 1.3). For instance, the energy difference between CHAIR and the most stable pseudodiequatorial conformer of chorismate can be as much as 18 kcal/mol. It is interesting to note from Table 1.3 that while the results from the SCC-DFTB semiempirical method are rather close to the ab initio results, the AMI method can overestimate the stability of the CHAIR conformer by as much as 10 kcal/mol in the gas phase. 

This suggests that care must be excised in choosing proper computational methods for the study of the Claisen rearrangement of chorismate. 

To explore the possible solution conformers, Guo et al. [82] performed QM/MM molecular dynamics simulations using the CHARMM program [86] the CHAIR 

Conformer (kcal-moC) R (A) (degrees) T2 (degrees) T (degrees) d (degrees) 

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