Is chorismate mutase a prototypic entropy trap? Activation parameters for the Bacillus subtilis enzyme

Chorismate mutase is thought to accelerate the chorismate-to-prephenate rearrangement in part by significantly lowering the entropy barrier for the reaction. We have determined the activation parameters for the well-characterized Bacillus subtilis chorismate mutase and find that Delta S double dagger (-9.1 +/- 1.2 eu) is nearly as unfavorable as the activation entropy for the uncatalyzed process. Our results suggest that chorismate mutase catalysts show greater mechanistic versatility than commonly believed. Copyright (C) 1996 Elsevier Science Ltd.