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

0379013 - ÚOCHB 2013 RIV DE eng J - Journal Article
Shleev, S. - Andoralov, V. - Falk, M. - Reimann, C. T. - Ruzgas, T. - Srnec, Martin - Ryde, U. - Rulíšek, Lubomír
On the Possibility of Uphill Intramolecular Electron Transfer in Multicopper Oxidases: Electrochemical and Quantum Chemical Study of Bilirubin Oxidase.
Electroanalysis. Roč. 24, č. 7 (2012), s. 1524-1540. ISSN 1040-0397. E-ISSN 1521-4109
Grant - others:7th Framework Program(XE) NMP4-SL-2009-229255
Institutional research plan: CEZ:AV0Z40550506
Keywords : bilirubin oxidase * intramolecular electron transfer * rate-limiting catalytic step * reorganization energy * QM/MM calculations
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 2.817, year: 2012

The detailed characterization of the kinetic and electrochemical properties of bilirubin oxidase (BOx) - a member of the MCO family - is reported. The experimental results strongly indicate that under certain conditions, e.g. in alkaline solutions, the intramolecular electron transfer (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.
Permanent Link: http://hdl.handle.net/11104/0210300