| 1. |
- Falk, Magnus, et al.
(författare)
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Mechanism of Bilirubin Oxidase : Fabrication and Characterization of Efficient Biocathode
- 2010
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Ingår i: Meeting abstracts (Electrochemical Society). - : ECS. - 1091-8213 .- 2151-2043. ; MA2010-02:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- To elucidate the mechanism of bilirubin oxidase (BOx)function in order to design efficient and stablebiocathodes working at different conditions, the enzymewas studied thoroughly. BOx is a copper-containing redoxenzyme that catalyzes the oxidation of a variety ofdifferent organic and inorganic compounds withconcomitant reduction of O2 directly to H2O.
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| 2. |
- Hu, LiHong, et al.
(författare)
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Reorganization Energy for Internal Electron Transfer in Multicopper Oxidases.
- 2011
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:Online September 28, 2011, s. 13111-13126
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Tidskriftsartikel (refereegranskat)abstract
- We have calculated the reorganization energy for the intramolecular electron transfer between the reduced type 1 copper site and the peroxy intermediate of the trinuclear cluster in the multicopper oxidase CueO. The calculations are performed at the combined quantum mechanics and molecular mechanics (QM/MM) level, based on molecular dynamics simulations with tailored potentials for the two copper sites. We obtain a reorganization energy of 91-133 kJ/mol, depending on the theoretical treatment. The two Cu sites contribute by 12 and 22 kJ/mol to this energy, whereas the solvent contribution is 34 kJ/mol. The rest comes from the protein, involving small contributions from many residues. We have also estimated the energy difference between the two electron-transfer states and show that the reduction of the peroxy intermediate is exergonic by 43-87 kJ/mol, depending on the theoretical method. Both the solvent and the protein contribute to this energy difference, especially charged residues close to the two Cu sites. We compare these estimates with energies obtained from QM/MM optimizations and QM calculations in a vacuum and discuss differences between the results obtained at various levels of theory.
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| 3. |
- Shleev, Sergey, et al.
(författare)
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On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase
- 2012
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Ingår i: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 24:7, s. 1524-1540
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic cycle of multicopper oxidases (MCOs) involves intramolecular electron transfer (IET) from the Cu-T1 copper ion, which is the primary site of the one-electron oxidations of the substrate, to the trinuclear copper cluster (TNC), which is the site of the four-electron reduction of dioxygen to water. In this study we report a detailed characterization of the kinetic and electrochemical properties of bilirubin oxidase (BOx) a member of the MCO family. The experimental results strongly indicate that under certain conditions, e.g. in alkaline solutions, the IET can be the rate-limiting step in the BOx catalytic cycle. The data also suggest that one of the catalytically relevant intermediates (most likely characterized by an intermediate oxidation state of the TNC) formed during the catalytic cycle of BOx has a redox potential close to 0.4 V, indicating an uphill IET process from the T1 copper site (0.7 V) to the Cu-T23. These suggestions are supported by calculations of the IET rate, based on the experimentally observed Gibbs free energy change and theoretical estimates of reorganization energy obtained by combined quantum and molecular mechanical (QM/MM) calculations.
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