Home
This Title All WIREs
WIREs RSS Feed
How to cite this WIREs title:
WIREs Comput Mol Sci
Impact Factor: 14.016

Kinetic isotope effects in chemical and biochemical reactions: physical basis and theoretical methods of calculation

Full article on Wiley Online Library:   HTML PDF

Can't access this content? Tell your librarian.

Kinetic isotope effects (KIEs) are a valuable tool for the analysis of chemical and biochemical reaction mechanisms. Theoretical methods of calculation of those KIEs have been developed with the aim to better understand their experimental behavior. In this review, the physical basis as well as several of those computational approaches to calculate primary hydrogen KIEs is presented. Examples of interesting chemical reactions and relevant enzymatic processes are given to demonstrate how theory is used to interpret those complex kinetic magnitudes. In particular, KIE computations within generalized transition state theory formulations are shown here to explain the temperature dependence of chemical and biochemical KIEs caused by multidimensional quantum effects contributions, such as zero point vibrational energy and quantum tunneling. An unexpected large isotope effect on the phosphorescence emission of an organic reaction is analyzed by means of KIE calculations as a function of energy and including also tunneling corrections. More quantum‐based methodologies such as the Multiconfiguration Time‐Dependent Hartree method and Feynman path integral simulations are discussed within the context of KIE computations. The special kinetic treatment of proton‐coupled electron transfer reactions is also analyzed. WIREs Comput Mol Sci 2016, 6:584–603. doi: 10.1002/wcms.1268

Computed free‐energy profiles (with quantized vibration contributions included) along the reaction coordinate for the ecDHFR catalyzed reaction at 5 and 45°C. The same profiles for the gas‐phase hydrogen transfer reaction of CH3 + H2 are shown for comparison, where the reaction coordinate is distance along the mass‐scaled minimum‐energy path (scaled to mass of 1 amu). All curves have been normalized at the top to emphasize the difference in the barrier shape as temperature changes. (Reprinted with permission from Ref . Copyright 2005 American Chemical Society)
[ Normal View | Magnified View ]
Temperature dependence of KIEs for the ecDHFR‐catalyzed and a gas‐phase hydrogen transfer reaction with a similar magnitude to that of the KIEs. (Reprinted with permission from Ref . Copyright 2005 American Chemical Society)
[ Normal View | Magnified View ]
Schematic diagram showing the generalized activation free energy as a function of s. (Reprinted with permission from Ref . Copyright 2004 American Chemical Society)
[ Normal View | Magnified View ]
Experimental Arrhenius plot for Mu + C2H2 (experimental values: red squares; fitted line: red line); calculated Arrhenius plots for H + C2H2 (from Ref : dark green; from Ref : light green) and for D + C2H2 (from Ref : magenta line). (Reprinted with permission from Ref . Copyright 2015 American Chemical Society)
[ Normal View | Magnified View ]
Potential energy profile and adiabatic potential energy profiles as a function of the DCP coordinate for the X + C2H4 addition reaction with X = H, D, and Mu. The location of the saddle point and the variational transition states for each isotope variant is shown. (Reprinted with permission from Ref . Copyright 1999 American Chemical Society)
[ Normal View | Magnified View ]
Arrhenius plots corresponding to the CVT and CVT/SCT rate constants for the X + C2H4 addition reaction with X = H, D and Mu. (Reprinted with permission from Ref . Copyright 1998 American Chemical Society)
[ Normal View | Magnified View ]
Theoretical and experimental KIEs: (a) k D /k Heμ and (b) k Mu /k Heμ as a function of temperature. (Reprinted with permission from Ref . Copyright 2011 AIP Publishing LLC)
[ Normal View | Magnified View ]
Survival probabilities for the hydrogen and deuterium transfers for the first 50 fs of propagation. The horizontal line sets the point where the 50% of the reactant turns into product. (Reprinted with permission from Ref . Copyright 2006 American Chemical Society)
[ Normal View | Magnified View ]
Kinetic isotope effect (KIE) in logarithmic scale as a function of the energy. (Reprinted with permission from Ref . Copyright 2004 American Chemical Society)
[ Normal View | Magnified View ]

Related Articles

Studying molecular quantum dynamics with the multiconfiguration time‐dependent Hartree method
Theory and simulation of atom tunneling in chemical reactions

Browse by Topic

Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics
Structure and Mechanism > Reaction Mechanisms and Catalysis

Access to this WIREs title is by subscription only.

Recommend to Your
Librarian Now!

The latest WIREs articles in your inbox

Sign Up for Article Alerts