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On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase

Shleev, Sergey; Andoralov, Viktor; Falk, Magnus; Reimann, Curt LU ; Ruzgas, Tautgirdas; Srnec, Martin; Ryde, Ulf LU and Rulisek, Lubomir (2012) In Electroanalysis 24(7). p.1524-1540
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bilirubin oxidase, Intramolecular electron transfer, Rate-limiting, catalytic step, Reorganization energy, QM, MM calculations
in
Electroanalysis
volume
24
issue
7
pages
1524 - 1540
publisher
John Wiley & Sons
external identifiers
  • wos:000305999200006
  • scopus:84863550109
ISSN
1040-0397
DOI
10.1002/elan.201200188
language
English
LU publication?
yes
id
80e1647d-5bd1-40b6-87f1-ddf900477d28 (old id 3001445)
date added to LUP
2012-08-21 12:15:03
date last changed
2017-10-01 04:30:30
@article{80e1647d-5bd1-40b6-87f1-ddf900477d28,
  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.},
  author       = {Shleev, Sergey and Andoralov, Viktor and Falk, Magnus and Reimann, Curt and Ruzgas, Tautgirdas and Srnec, Martin and Ryde, Ulf and Rulisek, Lubomir},
  issn         = {1040-0397},
  keyword      = {Bilirubin oxidase,Intramolecular electron transfer,Rate-limiting,catalytic step,Reorganization energy,QM,MM calculations},
  language     = {eng},
  number       = {7},
  pages        = {1524--1540},
  publisher    = {John Wiley & Sons},
  series       = {Electroanalysis},
  title        = {On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase},
  url          = {http://dx.doi.org/10.1002/elan.201200188},
  volume       = {24},
  year         = {2012},
}