Encyclopedia of Biophysics

Living Edition
| Editors: Gordon Roberts, Anthony Watts, European Biophysical Societies

Kinetic Isotope Effects

  • Clive R. BagshawEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-35943-9_58-1



Kinetic isotope effects reflect the consequences of the change in atomic mass on the kinetics of a reaction when a heavy isotope (e.g., deuterium) is substituted for a lighter atom (e.g., protium). The information obtained can help identify the contribution of bond-making and bond-breaking steps to the rate-limiting step of a reaction pathway, as well as assessing the role of quantum tunneling in a mechanism.

Basic Characteristics

Isotopes are widely used to study chemical mechanisms as they can identify the fate of atoms within a reactant as it is converted to product. A classic example is the identification of the site of hydrolysis of a compound by determining the fate of an 18O (heavy oxygen) atom when hydrolysis is carried out in H 2 18O. Heavy isotopes can also change the kinetics of a reaction and this may also provide valuable information (Cook 1991; Cook and Cleland 2007; Fersht 1999). In classical theory, this effect is attributed to...
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Copyright information

© European Biophysical Societies' Association (EBSA) 2018

Authors and Affiliations

  1. 1.Department of Chemistry and BiochemistryUniversity of California Santa CruzSanta CruzUSA

Section editors and affiliations

  • Clive R. Bagshaw
    • 1
  1. 1.Department of Chemistry and BiochemistryUniversity of California at Santa CruzSanta CruzUSA