THE MECHANISM OF THE CATALYSIS OF THE CLAISEN REARRANGEMENT OF CHORISMATE TO PREPHENATE BY THE CHORISMATE MUTASE FROM BACILLUS-SUBTILIS - AMOLECULAR MECHANICS AND HYBRID QUANTUM-MECHANICAL MOLECULAR MECHANICAL STUDY

The role of the active site of the chorismate mutase from Bacillus sub tilis in catalysing the Claisen rearrangement of chorismate to prephen ate is studied computationally using both molecular mechanics and a hy brid quantum mechanical/molecular mechanical method. Structures along the pathway calculated at the HF/6-31G level are docked into the acti ve site and reveal that the hydrogen bonding interactions reflect the changing geometry and electronic structure of the substrate. In partic ular the interactions are maximal close to the transition state and le ad to a barrier lowering greater than that needed to produce the obser ved rate acceleration in line with conclusions that the chemical trans formation is not the rate determining process.