Heme-heme interaction in cytochrome oxidase

Wilson, David F.; Lindsay, J. Gordon; Brocklehurst, Elizabeth

doi:10.1016/0005-2728(72)90058-8

Cited by 183 publications

(62 citation statements)

References 19 publications

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“…Nonetheless, the EPR titrations suggest that the potentiometric properties of the individual hemes are divergent in the fragments and full-length protein and they demonstrate the existence of cooperative interactions between them. This behavior was also suggested in other multi redox center proteins, including diheme cyt c4 [33], cyt c oxidase [47,48] and tetraheme cyt c3 [49,50]. Interestingly, as a consequence of the interaction scheme, the N-terminal domain is easier to reduce than the C-terminal domain in the full-length protein.…”

Section: Potentiometric Titrations Followed By Epr Spectroscopysupporting

confidence: 55%

Electrochemical study of an electron shuttle diheme protein: The cytochrome c from T. thermophilus

Melin

Schoepp‐Cothenet²,

Abdulkarim³

et al. 2017

Inorganica Chimica Acta

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ABSTRACT:Cytochrome c550, a diheme protein from the thermophilic bacterium Thermus thermophilus, is involved in an alternative respiration pathway allowing the detoxification of sulfite ions. It transfers the two electrons released from the oxidation of sulfite in a sulfite:cytochrome c oxidoreductase (SOR) enzyme to heme/copper oxidases via the monoheme cytochrome c552. It consists of two conformationally independent and structurally different domains (the C-and Nterminal) connected by a flexible linker. Both domains harbor one heme moiety. We report here the redox properties of the full-length protein and the individual C-and N-terminal fragments.We show by UV/Vis and EPR potentiometric titrations that the two fragments exhibit very similar potentials, despite their different environments. In the full-length protein, however, the N-terminal heme is easier to reduce than the C-terminal one, due to cooperative interactions.This finding is consistent with the kinetic measurements which showed that the N-terminal domain only accepts electrons from the SOR. Cytochrome c552 is able to interact with its partners both through electrostatic and hydrophobic interactions as could be shown by measuring efficient electron transfer at gold electrodes modified with charged and hydrophobic groups, respectively. The coupling of electrochemistry with infrared spectroscopy allowed us to monitor the conformational changes induced by electron transfer to each heme separately and to both simultaneously.

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Section: Potentiometric Titrations Followed By Epr Spectroscopysupporting

confidence: 55%

Electrochemical study of an electron shuttle diheme protein: The cytochrome c from T. thermophilus

Melin

Schoepp‐Cothenet²,

Abdulkarim³

et al. 2017

Inorganica Chimica Acta

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“…Reduction studies [34,35] of the enzyme in the presence of cyanide and azide as well as potentiometric titrations [24,25,36,37] have shown that both hemes in cytochrome c oxidase contribute about equally to the difference spectrum reduced minus oxidized at 445 nm. It has also been demonstrated [19] that the absorbance difference of cytochrome a:+ .…”

Section: Discussionmentioning

confidence: 99%

“…At 605 nm, the CO-induced changes are more difficult to interpret since at this wavelength the contribution of both cytochromes in the absence of ligands is about equal [24,25,36,37], whereas in the presence of ligands like cyanide and CO [20,25,28] the contribution of cytochrome a increases to approximately 80% of the reduced minus oxidized absorbance difference. Thus the binding of CO or cyanide to cytochrome a3 affects the absorbance coefficient of reduced cytochrome a.…”

Section: Discussionmentioning

confidence: 99%

The Binding of Carbon Monoxide to Cytochrome c Oxidase

et al. 1977

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The effect of CO on the optical absorbance spectrum of partially reduced cytochrome c oxidase has been studied. The changes at 432 and 590 nm suggest that the cytochrome a:+ . CO compound is formed preferentially and that concomitantly a second electron is taken up by the enzyme. From the CO-induced changes at 830 nm it is concluded that in the partially reduced enzyme addition of CO causes reoxidation of the copper component of cytochrome c oxidase.Addition of CO to partially reduced enzyme (2 electrons per 4 metal ions) also brings about a decrease in the intensities of electron paramagnetic resonance signals of high-spin heme iron near g = 6 and of the low-spin heme at g = 2.6. Concomitantly both the low-spin heme a signal at g = 3 and the copper signal at g = 2 increase in intensity. These results demonstrate that formation of the reduced diamagnetic cytochrome a3 . CO compound is accompanied by reoxidation of both the copper component detectable by electron paramagnetic resonance and possibly also by cytochrome a.

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“…Recently, there has been a great deal of interest in the chemical and physical properties of various inhibitor complexes of cytochrome c oxidase [3][4][5][6][7]. In particular, considerable effort has been spent on studying the cyanideand carbon monoxide-bound protein with the hope of trapping one or more of the metal components in the oxidized or reduced form [8][9][10][11]. The rationale for such studies is the possibility that 'mixed valence' forms of the CN-or CO-inhibited protein might provide some clues about the mechanistic pathway of electron transfer to oxygen as well as the interaction of the four metal components in the functional protein.…”

Section: Introductionmentioning

confidence: 99%

“…The rationale for such studies is the possibility that 'mixed valence' forms of the CN-or CO-inhibited protein might provide some clues about the mechanistic pathway of electron transfer to oxygen as well as the interaction of the four metal components in the functional protein. In fact, on the basis of spectroscopic and electrochemical properties of the CO and azide complexes of cytochrome c oxidase, Wilson et al have proposed that there exists a direct heine-heine interaction in the protein [9]. On the other hand, Yong and King have postulated a heme-copper-heme interaction based on their studies of a 'half-reduced *To whom requests for reprints should be sent +Present address: Stanford Synchrotron Radiation Project, Stanford Linear Accelerator Center, Stanford, CA 94305, USA and a fully-reduced CN complex of the oxidase [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

X‐ray absorption edge studies on cyanide‐bound cytochrome c oxidase

Chan

1977

FEBS Letters

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Heme-heme interaction in cytochrome oxidase

Cited by 183 publications

References 19 publications

Electrochemical study of an electron shuttle diheme protein: The cytochrome c from T. thermophilus

Electrochemical study of an electron shuttle diheme protein: The cytochrome c from T. thermophilus

The Binding of Carbon Monoxide to Cytochrome c Oxidase

X‐ray absorption edge studies on cyanide‐bound cytochrome c oxidase

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