Aspects of hybrid QM/MM calculations: The treatment of the QM/MM interfaceregion and geometry optimization with an application to chorismate mutase

The location of stationary points on potential energy surfaces calculated b y hybrid quantum mechanical (QM)/molecular mechanical (MM) methods, allowin g for relaxation of both the QM and MM regions, is discussed and illustrate d with results from a study of the enzyme chorismate mutase. Enhanced inter actions between carboxylate groups and neighboring arginine residues are sh own to be important in the catalysis of chorismate to prephenate by this en zyme. The treatment of the interface between the QM and MM regions is studi ed by calculations on a series of models of amino acids. (C) 2000 John Wile y & Sons, dInc.