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Role of the HoxZ Subunit in the Electron Transfer Pathway of the Membrane-Bound [NiFe]-Hydrogenase from Ralstonia eutropha Immobilized on Electrodes
Zitatschlüssel Sezer2011
Autor Sezer, Murat and Frielingsdorf, Stefan and Millo, Diego and Heidary, Nina and Utesch, Tillman and Mroginski, Maria-Andrea and Friedrich, Baerbel and Hildebrandt, Peter and Zebger, Ingo and Weidinger, Inez M.
Seiten 10368–10374
Jahr 2011
Journal Journal Of Physical Chemistry B
Jahrgang 115
Nummer 34
Monat sep
Zusammenfassung The role of the diheme cytochrome b (HoxZ) subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase (MBH) heterotrimer from Ralstonia eutropha H16 has been investigated. The MBH in its native heterotrimeric state was immobilized on electrodes and subjected to spectroscopic and electrochemical analysis. Surface enhanced resonance Raman spectroscopy was used to monitor the redox and coordination state of the HoxZ heme cofactors while concomitant protein film voltammetric measurements gave insights into the catalytic response of the enzyme on the electrode. The entire MBH heterotrimer as well as its isolated HoxZ subunit were immobilized on silver electrodes coated with self-assembled monolayers of omega-functionalized alkylthiols, displaying the preservation of the native heme pocket structure and an electrical communication between HoxZ and the electrode. For the immobilized MBH heterotrimer, catalytic reduction of the HoxZ heme cofactors was observed upon H(2) addition. The catalytic currents of MBH with and without the HoxZ subunit were measured and compared with the heterogeneous electron transfer rates of the isolated HoxZ. On the basis of the spectroscopic and electrochemical results, we conclude that the HoxZ subunit under these artificial conditions is not primarily involved in the electron transfer to the electrode but plays a crucial role in stabilizing the enzyme on the electrode.
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