In situ monitoring of the catalytic activity of cytochrome C oxidase in a biomimetic architecture |
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Authors: | Friedrich Marcel G Plum Markus A Santonicola M Gabriella Kirste Vinzenz U Knoll Wolfgang Ludwig Bernd Naumann Renate L C |
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Institution: | * Max Planck Institute for Polymer Research, 55128 Mainz, Germany † Goethe University, Frankfurt, Institute of Biochemistry, 60438 Frankfurt am Main, Germany |
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Abstract: | Cytochrome c oxidase (CcO) from Paracoccus denitrificans was immobilized in a strict orientation via a his-tag attached to subunit I on a gold film and reconstituted in situ into a protein-tethered bilayer lipid membrane. In this orientation, the cytochrome c (cyt c) binding site is directed away from the electrode pointing to the outer side of the protein-tethered bilayer lipid membrane architecture. The CcO can thus be activated by cyt c under aerobic conditions. Catalytic activity was monitored by impedance spectroscopy, as well as cyclic voltammetry. Cathodic and anodic currents of the CcO with cyt c added to the bulk solution were shown to increase under aerobic compared to anaerobic conditions. Catalytic activity was considered in terms of repeated electrochemical oxidation/reduction of the CcO/cyt c complex in the presence of oxygen. The communication of cyt c bound to the CcO with the electrode is discussed in terms of a hopping mechanism through the redox sites of the enzyme. Simulations supporting this hypothesis are included. |
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