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Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

preprint
revised on 17.09.2019 and posted on 23.09.2019 by Javier Oller, David A. Sáez, Esteban Vöhringer-Martinez

Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of changes in the molecular environment on reactivity. In this contribution, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.

Funding

Max-Planck Society Partner Group, Fondecyt 160193, Beca Doctorado Nacional 2015 CONICYT folio 21150596

History

Email Address of Submitting Author

evohringer@udec.cl

Institution

Universidad de Concepción

Country

Chile

ORCID For Submitting Author

0000-0003-1785-4558

Declaration of Conflict of Interest

None

Version Notes

version 1.0

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