Electronic wiring of cytochrome c oxidase (CcO) from R. sphaeroides to gold surfaces was employed to monitor redox changes through redox centers, CuA, heme a, heme a3 and CuB. Electrochemical investigations revealed that under aerobic and reducing conditions the enzyme undergoes a gradual transition into an activated state. It is only in this state that proton pumping and catalytic currents can be observed. The potential of the catalytic current, however, is shifted by 450 mV negative from the standard redox potential of CuA. In contrast, “correct” standard redox potentials of all the centers in the positive potential range can be observed if the enzyme kept under anaerobic and oxidizing conditions. Then no proton pumping does take place. This state is therefore considered as a non-activated state. The transition between the two states is fully reversible. This was also verified by electrochemically-controlled surface-enhanced infrared absorption spectroscopy (SEIRAS) and surface-enhanced resonance Raman spectroscopy (SERRS).
Two Conformations of the Cytochrome c Oxidase Discriminated by Spectro-Electrochemistry Using SEIRAS / Renate L. C., Naumann; Christoph, Nowak; Christofer, Luening; Santonicola, Mariagabriella; Jiapeng, Zhu; Robert B., Gennis; Wolfgang, Knoll. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - STAMPA. - 96:3(2009), pp. 565a-565a. (Intervento presentato al convegno 53rd Annual Meeting of the Biophysical Society tenutosi a Boston (MA), USA nel February 28 - March 4, 2009) [10.1016/j.bpj.2008.12.3707].
Two Conformations of the Cytochrome c Oxidase Discriminated by Spectro-Electrochemistry Using SEIRAS
SANTONICOLA, MARIAGABRIELLA;
2009
Abstract
Electronic wiring of cytochrome c oxidase (CcO) from R. sphaeroides to gold surfaces was employed to monitor redox changes through redox centers, CuA, heme a, heme a3 and CuB. Electrochemical investigations revealed that under aerobic and reducing conditions the enzyme undergoes a gradual transition into an activated state. It is only in this state that proton pumping and catalytic currents can be observed. The potential of the catalytic current, however, is shifted by 450 mV negative from the standard redox potential of CuA. In contrast, “correct” standard redox potentials of all the centers in the positive potential range can be observed if the enzyme kept under anaerobic and oxidizing conditions. Then no proton pumping does take place. This state is therefore considered as a non-activated state. The transition between the two states is fully reversible. This was also verified by electrochemically-controlled surface-enhanced infrared absorption spectroscopy (SEIRAS) and surface-enhanced resonance Raman spectroscopy (SERRS).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
