Back to Search
Start Over
Molecular-Level Insight into the Differential Oxidase and Oxygenase Reactivities of de Novo Due Ferri Proteins.
- Source :
-
Journal of the American Chemical Society [J Am Chem Soc] 2015 Jul 29; Vol. 137 (29), pp. 9302-14. Date of Electronic Publication: 2015 Jul 15. - Publication Year :
- 2015
-
Abstract
- Using the single-chain due ferri (DFsc) peptide scaffold, the differential oxidase and oxygenase reactivities of two 4A→4G variants, one with two histidines at the diiron center (G4DFsc) and the other with three histidines (3His-G4DFsc(Mut3)), are explored. By controlling the reaction conditions, the active form responsible for 4-aminophenol (4-AP) oxidase activity in both G4DFsc and 3His-G4DFsc(Mut3) is determined to be the substrate-bound biferrous site. Using circular dichroism (CD), magnetic CD (MCD), and variable-temperature, variable-field (VTVH) MCD spectroscopies, 4-AP is found to bind directly to the biferrous sites of the DF proteins. In G4DFsc, 4-AP increases the coordination of the biferrous site, while in 3His-G4DFsc(Mut3), the coordination number remains the same and the substrate likely replaces the additional bound histidine. This substrate binding enables a two-electron process where 4-AP is oxidized to benzoquinone imine and O2 is reduced to H2O2. In contrast, only the biferrous 3His variant is found to be active in the oxygenation of p-anisidine to 4-nitroso-methoxybenzene. From CD, MCD, and VTVH MCD, p-anisidine addition is found to minimally perturb the biferrous centers of both G4DFsc and 3His-G4DFsc(Mut3), indicating that this substrate binds near the biferrous site. In 3His-G4DFsc(Mut3), the coordinative saturation of one iron leads to the two-electron reduction of O2 at the second iron to generate an end-on hydroperoxo-Fe(III) active oxygenating species.
Details
- Language :
- English
- ISSN :
- 1520-5126
- Volume :
- 137
- Issue :
- 29
- Database :
- MEDLINE
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 26090726
- Full Text :
- https://doi.org/10.1021/jacs.5b03524