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Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

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Enthalpy-Entropy Compensation Effect in Chemical Kinetics and Experimental Errors: A Numerical Simulation Approach.

Joaquin F Perez-Benito¹, Mar Mulero-Raichs¹

¹Departamento de Ciencia de Materiales y Quimica Fisica, Seccion de Quimica Fisica, Facultad de Quimica, Universidad de Barcelona , Marti i Franques, 1, 08028 Barcelona, Spain.

The Journal of Physical Chemistry. A

|September 13, 2016

Summary

Statistical analysis of kinetic data suggests that observed activation enthalpy-entropy correlations in homologous reaction series are unlikely due to experimental error. These compensation plots likely reflect genuine physical relationships, not random noise.

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Area of Science:

Physical Chemistry
Chemical Kinetics
Statistical Analysis

Background:

Homologous reaction series often exhibit linear activation enthalpy-entropy correlations, termed compensation plots.
The slope of these plots indicates the isokinetic temperature, where rate constants are equal.
Statistical interdependence of experimental errors in activation enthalpy and entropy has been previously noted.

Purpose of the Study:

To investigate whether experimental errors can artificially generate linear compensation plots.
To develop a computational method for assessing the probability of error-induced correlations.
To evaluate the statistical significance of experimentally observed compensation plots in chemical kinetics.

Main Methods:

Numerical simulations were employed to explore the impact of experimental errors on kinetic parameters.
A computer program (p-test) was developed to calculate the probability of random error generating a compensation plot.
The program was applied to kinetic data from 100 homologous reaction series from literature.

Main Results:

The developed p-test evaluates the likelihood that experimental errors could produce a linear compensation plot.
Analysis of 100 homologous reaction series indicated that most reported compensation plots are statistically significant.
The observed correlations are highly improbable to arise solely from the accumulation of experimental errors.

Conclusions:

The study provides strong evidence against experimental error being the primary cause of activation enthalpy-entropy compensation plots.
The findings support the physical reality and mechanistic significance of these correlations in homologous reaction series.
A statistically robust method is now available for validating compensation plots in chemical kinetics research.