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

Van Severen, Marie-Céline LU ; Andrejić, Milica; Li, Jilai LU ; Starke, Kerstin LU ; Mata, Ricardo A; Nordlander, Ebbe LU and Ryde, Ulf LU (2014) In Journal of Biological Inorganic Chemistry 19(7). p.1165-1179
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Biological Inorganic Chemistry
volume
19
issue
7
pages
1165 - 1179
publisher
Springer
external identifiers
  • pmid:24957901
  • wos:000342438100009
  • scopus:84911094229
ISSN
1432-1327
DOI
10.1007/s00775-014-1172-z
language
English
LU publication?
yes
id
b22cbc99-19c6-4200-821e-37e0935a840a (old id 4527012)
date added to LUP
2014-08-08 16:15:17
date last changed
2017-06-11 03:21:16
@article{b22cbc99-19c6-4200-821e-37e0935a840a,
  abstract     = {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.},
  author       = {Van Severen, Marie-Céline and Andrejić, Milica and Li, Jilai and Starke, Kerstin and Mata, Ricardo A and Nordlander, Ebbe and Ryde, Ulf},
  issn         = {1432-1327},
  language     = {eng},
  number       = {7},
  pages        = {1165--1179},
  publisher    = {Springer},
  series       = {Journal of Biological Inorganic Chemistry},
  title        = {A quantum-mechanical study of the reaction mechanism of sulfite oxidase.},
  url          = {http://dx.doi.org/10.1007/s00775-014-1172-z},
  volume       = {19},
  year         = {2014},
}