• combined quantum mechanical/molecular mechanical method;
  • hydride transfer;
  • kinetic isotope effects;
  • potential of mean force;
  • proton transfer;
  • quantized vibrations;
  • quantum mechanical dynamics;
  • rate constants;
  • semiclassical theory of tunneling;
  • statistical theory


This paper provides an overview of a new method developed to include quantum mechanical effects and free energy sampling in calculations of reaction rates in enzymes. The paper includes an overview of variational transition state theory with optimized multidimensional tunneling for simple gas-phase reactions and then shows how this is extended to incorporate free energy effects and to include protein motions in the reaction coordinate by ensemble averaging. Finally we summarize recent comparisons to experiment for primary and secondary kinetic isotope effects for proton and hydride transfer reactions catalyzed by enzymes. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004