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A Modified Arrhenius Approach to Thermodynamically Study Regioselectivity in Cytochrome P450‐Catalyzed Substrate Conversion
Author(s) -
Luirink Rosa A.,
VerkadeVreeker Marlies C. A.,
Commandeur Jan N. M.,
Geerke Daan P.
Publication year - 2020
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201900751
Subject(s) - regioselectivity , substrate (aquarium) , chemistry , arrhenius equation , selectivity , catalysis , activation energy , cytochrome p450 , combinatorial chemistry , transition state , heme , computational chemistry , reaction rate , cytochrome , enzyme , organic chemistry , oceanography , geology
The regio‐ (and stereo‐)selectivity and specific activity of cytochrome P450s are determined by the accessibility of potential sites of metabolism (SOMs) of the bound substrate relative to the heme, and the activation barrier of the regioselective oxidation reaction(s). The accessibility of potential SOMs depends on the relative binding free energy (ΔΔ G bind ) of the catalytically active substrate‐binding poses, and the probability of the substrate to adopt a transition‐state geometry. An established experimental method to measure activation energies of enzymatic reactions is the analysis of reaction rate constants at different temperatures and the construction of Arrhenius plots. This is a challenge for multistep P450‐catalyzed processes that involve redox partners. We introduce a modified Arrhenius approach to overcome the limitations in studying P450 selectivity, which can be applied in multiproduct enzyme catalysis. Our approach gives combined information on relative activation energies, ΔΔ G bind values, and collision entropies, yielding direct insight into the basis of selectivity in substrate conversion.