The near attack conformation approach to the study of the chorismate to prephenate reaction.

Standard free energies (DeltaGN degree) for formation of near attack conformers, those ground state conformers that can convert directly to the transition state, were calculated for the Claisen rearrangement of chorismate to prephenate in six different environments: water, wild-type enzymes from Bacillus subtilis and Escherichia coli, their Arg90Cit and Glu52Ala mutants, and the 1F7 catalytic antibody. Values of the calculated DeltaGN degrees and the experimentally determined activation energies (DeltaG++) are linearly related with the slope of approximately equal to 1. This demonstrates that the relative rate of the chorismate --> prephenate reaction is overwhelmingly dependent on the efficiency of formation of near attack conformers in the ground state.