DFT Study on Enzyme Turnover Including Proton and Electron Transfers of Copper-Containing Nitrite Reductase.
Biochemistry
; 55(33): 4697-707, 2016 08 23.
Article
en En
| MEDLINE
| ID: mdl-27455866
The reaction mechanism of copper-containing nitrite reductase (CuNiR) has been proposed to include two important events, an intramolecular electron transfer and a proton transfer. The two events have been suggested to be coupled, but the order of these events is currently under debate. We investigated the entire enzyme reaction mechanism of nitrite reduction at the T2 Cu site in thermophilic Geobacillus CuNiR from Geobacillus thermodenitrificans NG80-2 (GtNiR) using density functional theory calculations. We found significant conformational changes of His ligands coordinated to the T2 Cu site upon nitrite binding during the catalytic reaction. The reduction potentials and pKa values calculated for the relevant protonation and reduction states show two possible routes, A and B. Reduction of the T2 Cu site in the resting state is followed by endothermic nitrite binding in route A, while exothermic nitrite binding occurs prior to reduction of the T2 Cu site in route B. We concluded that our results support the random-sequential mechanism rather than the ordered mechanism.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Cobre
/
Nitrito Reductasas
Idioma:
En
Revista:
Biochemistry
Año:
2016
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
Estados Unidos