A quantum-mechanical study of the reaction mechanism of sulfite oxidase.

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A quantum-mechanical study of the reaction mechanism of sulfite oxidase. / Van Severen, Marie-Céline; Andrejić, Milica; Li, Jilai; Starke, Kerstin; Mata, Ricardo A; Nordlander, Ebbe; Ryde, Ulf.

In: Journal of Biological Inorganic Chemistry, Vol. 19, No. 7, 2014, p. 1165-1179.

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Van Severen, Marie-Céline ; Andrejić, Milica ; Li, Jilai ; Starke, Kerstin ; Mata, Ricardo A ; Nordlander, Ebbe ; Ryde, Ulf. / A quantum-mechanical study of the reaction mechanism of sulfite oxidase. In: Journal of Biological Inorganic Chemistry. 2014 ; Vol. 19, No. 7. pp. 1165-1179.

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TY - JOUR

T1 - A quantum-mechanical study of the reaction mechanism of sulfite oxidase.

AU - Van Severen, Marie-Céline

AU - Andrejić, Milica

AU - Li, Jilai

AU - Starke, Kerstin

AU - Mata, Ricardo A

AU - Nordlander, Ebbe

AU - Ryde, Ulf

N1 - The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039), Chemical Physics (S) (011001060)

PY - 2014

Y1 - 2014

N2 - The oxidation of sulfite to sulfate by two different models of the active site of sulfite oxidase has been studied. Both protonated and deprotonated substrates were tested. Geometries were optimized with density functional theory (TPSS/def2-SV(P)) and energies were calculated either with hybrid functionals and large basis sets (B3LYP/def2-TZVPD) including corrections for dispersion, solvation, and entropy, or with coupled-cluster theory (LCCSD(T0)) extrapolated toward a complete basis set. Three suggested reaction mechanisms have been compared and the results show that the lowest barriers are obtained for a mechanism where the substrate attacks a Mo-bound oxo ligand, directly forming a Mo-bound sulfate complex, which then dissociates into the products. Such a mechanism is more favorable than mechanisms involving a Mo-sulfite complex with the substrate coordinating either by the S or O atom. The activation energy is dominated by the Coulomb repulsion between the Mo complex and the substrate, which both have a negative charge of -1 or -2.

AB - The oxidation of sulfite to sulfate by two different models of the active site of sulfite oxidase has been studied. Both protonated and deprotonated substrates were tested. Geometries were optimized with density functional theory (TPSS/def2-SV(P)) and energies were calculated either with hybrid functionals and large basis sets (B3LYP/def2-TZVPD) including corrections for dispersion, solvation, and entropy, or with coupled-cluster theory (LCCSD(T0)) extrapolated toward a complete basis set. Three suggested reaction mechanisms have been compared and the results show that the lowest barriers are obtained for a mechanism where the substrate attacks a Mo-bound oxo ligand, directly forming a Mo-bound sulfate complex, which then dissociates into the products. Such a mechanism is more favorable than mechanisms involving a Mo-sulfite complex with the substrate coordinating either by the S or O atom. The activation energy is dominated by the Coulomb repulsion between the Mo complex and the substrate, which both have a negative charge of -1 or -2.

U2 - 10.1007/s00775-014-1172-z

DO - 10.1007/s00775-014-1172-z

M3 - Article

C2 - 24957901

VL - 19

SP - 1165

EP - 1179

JO - Journal of Biological Inorganic Chemistry

JF - Journal of Biological Inorganic Chemistry

SN - 1432-1327

IS - 7

ER -