Measurement and Prediction of Chlorine Kinetic Isotope Effects in Enzymatic Systems

Approaches to determine chlorine  kinetic isotope effects  (Cl-KIEs) on enzymatic  dehalogenations  are discussed and illustrated by representative examples. Three aspects are considered. First methodology for experimental measurement of Cl-KIEs, with stress being on FAB-IRMS technique developed in our laboratory, is described. Subsequently, we concentrate our discussion on the consequences of reaction complexity in the interpretation of experimental values, a problem especially important in cases of polychlorinated reactants. The most fruitful studies of enzymatic dehalogenations by Cl-KIEs require their theoretical evaluation, hence the computational focus of the second part of this chapter.