A re‐evaluation of the spectral, potentiometric and energy‐linked properties of cytochrome <i>c</i> oxidase in mitochondria

Wikström, Mårtin K.F.; Harmon, H. James; Ingledew, W. John; Chance, Britton

doi:10.1016/0014-5793(76)80127-5

Cited by 174 publications

(83 citation statements)

References 45 publications

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“…Although the above data do not allow to conclude that all a3 reacting with 02 goes to the fully oxidized form, on the basis of the 655 nm band, at 3+ least a significant amount of a] ÷ reaches the a2 state. Furthermore, considering the oxidation of cytochrome a implied by the one of cytochrome c, the above data support strongly a progression of cytochrome oxidase to the fully oxidized state which was not expected from heine-heine interaction considerations [8].…”

Section: Resultssupporting

confidence: 60%

“…One questionable point has been the redox level of hemes a and a 3 in the stage of Compound C and Compound B formation. Several identifications have been proposed [4][5][6][7][8][9] which did or did not involve the fully oxidized state. On the basis of their heme-heme interaction model, Wikstrom et al [8] suggested that the mechanism of oxygen reduction by cytochrome oxidase does not involve the fully oxidized form.…”

Section: Introductionmentioning

confidence: 99%

“…Several identifications have been proposed [4][5][6][7][8][9] which did or did not involve the fully oxidized state. On the basis of their heme-heme interaction model, Wikstrom et al [8] suggested that the mechanism of oxygen reduction by cytochrome oxidase does not involve the fully oxidized form. Recently Beinert et al [10] characterized specifically the aT ÷ form with the 655 nm band that they pointed out previously by reflectance spectroscopy [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

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The involvement of the fully oxidized state in cytochrome oxidase reaction with oxygen studied with the 655 nm band as a probe

Denis

1977

FEBS Letters

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The involvement of the fully oxidized state in cytochrome oxidase reaction with oxygen studied with the 655 nm band as a probe

Denis

1977

FEBS Letters

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“…2A, where it is evident that the 604 nm peak shows only a small degree of haem a reduction at a potential where the 655 nm band is almost abolished. In fact, the 655 nm band Scarcely changes below 330 mV, even though about 65°70 of the Assuming that the MCD data of Kojima and Palmer [9] and the 'neoclassical model' [13,14] are basically correct) the difference spectrum over the I00=320 mV region should contain a high-spin haem a~ contribution that is free from the 655 nm feature. After subtraction of standard spectra of cytochromes c, f and a, we obtain the upper trace of Fig.…”

Section: Results and Discussionmentioning

confidence: 99%

The assignment of the 655 nm spectral band of cytochrome oxidase

Mitchell

Rich

1991

FEBS Letters

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The si~clral characteristicat of the '6~S no' hand of eytochmme o,~idase were found to I~ alT~=t~d by Ill, ands of the binuclear centre, includlnll formate and chloride, and by the reslintl/polsed transition. The bttnd tttrated wirlt n¢,r ,~ ~ I characteristics at a midpoint or about 400 mV, in contrast to h.em u~, which exhibits strong redox interaction and a tilralion ranlle al stltlniflcantly lower polcntial. Thus. altl~outlh Ihe total reduced. oxidised difference Sly=tram of haem u~ shows a tPoui!h at about 6J,$ no. this char=cteristi¢ is absent in the low potential rcllion. The 6.~S am t+eature may arise from a charge transfer band of ferric i~i$h.,+pin haem u. which is modulated b), the re¢lo~ state of Co#, as so|jested by Beinert et al, [(1976) Biochtm. Biophys. Acta 423, 339~35~].

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“…Cytochrome a, initially oxidized in the mixed valence state compound, appears to remain oxidized in compound C in spite of the interesting suggestion that electron equilibration between heme a and a3 occurs (22). However, the 830 nm absorption band attributed to ferricyanide-oxidized copper associated with heme a persists in the formation of compound C, as does the g = 3.05 electron spin resonance signal (3,4).…”

Section: Discussionmentioning

confidence: 94%

Oxygen intermediates and mixed valence states of cytochrome oxidase: infrared absorption difference spectra of compounds A, B, and C of cytochrome oxidase and oxygen.

Chance¹,

Leigh²

1977

Proc. Natl. Acad. Sci. U.S.A.

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A study of the near-infrared absorption spectra of three oxygen compounds of membrane-bound cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase; EC 1.9.3.1) shows that the formation of compound A (oxycytochrome oxidase) causes no significant infrared absorbance changes at -1030. At -640, the formation of compound C from the mixed-valence state of the oxidase leads to increased absorption at [740][741][742][743][744][745][746][747][748][749][750] Three compounds-A, B, and C-are formed in the reaction of cytochrome oxidase with oxygen at significant concentrations at very low temperatures. They form at rates that can be extrapolated with consistency to agree with the rates of electron transfer in cytochrome oxidase as measured at room temperature in the solubilized (1, 2) and membrane-bound (3, 4) enzyme. Thus, compounds A and B appear to be functional intermediates in the oxidase reaction and seem to differ significantly from the various "oxygenated" species of cytochrome oxidase found in the presence of dithionite and oxygen (5,6) and not observed at low temperatures.The most unusual, and in many ways the most interesting, compound is C (3, 4), formed from the partially oxidized or mixed valence state oxidase (7,8) in which cytochrome a and its associated copper (9) are oxidized prior to reaction with oxygen. Cytochrome a3 reduced (and bound to CO) and its associated copper atom is presumed to remain reduced as well (7,8 This communication describes the unique infrared absorption spectra of compound C in relation to those of compounds A and B, and proposes a new structure for compound C. METHODS A split-beam, split photolysis spectrophotometer (10) was adapted to precise scanning of the infrared region of the cytochrome oxidase spectrum from 700 to 900 nm. Baseline errors in this spectral region were recorded in the digital memory. The cuvette was then illuminated on half its area to cause photolysis of the a32+-CO compound and initiation of the reaction with oxygen in the illuminated portion of the sample; the unilluminated portion still contained a32+.CO. The computer memory corrected for the baseline errors and gave the corrected difference spectrum between the two portions of the sample.Since frozen samples were usually used, no septum between the two parts was needed. No nonspecific light-scattering change was observed in the frozen sample held at constant temperature.Frozen-thawed beef heart mitochondria prepared according to the method of L6w and Vallin (11) (kindly donated by C. P. Lee) were suspended in 30% ethylene glycol (freezing point, -22°), 0.1 M mannitol, and 5 mM Tris-sulfate buffer, pH 7.4. The mitochondria, at approximately 30 mg of protein per ml, supplemented with 5 mM glutamate and 5 mM succinate, were saturated with CO, supplemented with 30% ethylene glycol by volume, resaturated with CO, and maintained at 00 [or, for longer storage, at -200, at which the preparation is stable for at least a week (12)]. Electron transport from succinate to oxygen is inhibited by about ...

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A re‐evaluation of the spectral, potentiometric and energy‐linked properties of cytochrome c oxidase in mitochondria

Cited by 174 publications

References 45 publications

The involvement of the fully oxidized state in cytochrome oxidase reaction with oxygen studied with the 655 nm band as a probe

The involvement of the fully oxidized state in cytochrome oxidase reaction with oxygen studied with the 655 nm band as a probe

The assignment of the 655 nm spectral band of cytochrome oxidase

Oxygen intermediates and mixed valence states of cytochrome oxidase: infrared absorption difference spectra of compounds A, B, and C of cytochrome oxidase and oxygen.

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