<i>Appendix</i>—Spectrum of horse-heart cytochrome <i>c</i>

Margoliash, E.; Frohwirt, Nehamah

doi:10.1042/bj0710570

Cited by 827 publications

(452 citation statements)

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“…These minimised the possibility of reversed electron transfer through centre o of the bo complex and also raised the midpoint potential of the iron sulphur centre above + 500 mV [23] so that it could not change redox state during the experiment. Extinction coefficients of 21.85 [19][20][21], 21.9 [24] and 1 mM -1 .cm -1 (see above) were used to quantitate the optical changes of aA, ¢, and CUA, respectively. In addition, the changes of cytochromes c and a were corrected for their small mutual overlap (e of oxidase at 550-575 nm= +3.1 mM-~.cm-1; e of cytochrome c at 605-630 nm= -0.3 mM -1. cm-]).…”

Section: Quantitation Of the Electronic Redistributionmentioning

confidence: 99%

The location of Cu_A in mammalian cytochrome c oxidase

1988

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Imposition of a protonmotive force across the inner membrane of coupled cyanide-inhibited, beef heart mitochondria by addition of ATP causes reduction of cytochrome c and Cu^ with concomitant oxidation of haem aA. The data are consistent with previous demonstrations of an intramembrane location of haem a^ but further indicate that CUA is very close to the cytosolic surface of the membrane. The implications of this finding for electron transfer route and the site of the proton pumping chemistry are discussed.

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Section: Quantitation Of the Electronic Redistributionmentioning

confidence: 99%

The location of Cu_A in mammalian cytochrome c oxidase

1988

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“…However, in the blue region of the spectra, the absorption changes associated with the binding of oxygen or CO and/or with the redox changes of hemes a∕a 3 , monitored at 445 nm, had to be corrected for overlapping spectral contributions from cytochrome c and flavoproteins. According to the cytochrome c difference spectra found in the literature (60), and assuming that the reduced minus oxidized flavoprotein extinction is roughly constant from 445 to 470 nm, a deconvolution for the CcOx signal is given by:…”

Section: Methodsmentioning

confidence: 99%

Questioning the functional relevance of mitochondrial supercomplexes by time-resolved analysis of the respiratory chain

Trouillard

Meunier

Rappaport

2011

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

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Mitochondria are the powerhouses of eukaryotic cells as they feed metabolism with its major substrate. Oxidative-phosphorylation relies on the generation, by an electron/proton transfer chain, of an electrochemical transmembrane potential utilized to synthesize ATP. Although these fundamental principles are not a matter of debate, the emerging picture of the respiratory chain diverges from the linear and fluid scheme. Indeed, a growing number of pieces of evidence point to membrane compartments that possibly restrict the diffusion of electron carriers, and to supramolecular assembly of various complexes within various kinds of supercomplexes that modulate the thermodynamic and kinetic properties of the components of the chain. Here, we describe a method that allows the unprecedented time-resolved study of the respiratory chain in intact cells that is aimed at assessing these hypotheses. We show that, in yeast, cytochrome c is not trapped within supercomplexes and encounters no particular restriction to its diffusion which questions the functional relevance of these supramolecular edifices.bioenergetics | electon transfer | respiration | compartmentalization

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“…Horse heart cyt c was purchased from Sigma, oxidized with K[Co(EDTA)] prepared by a literature method (20), and purified by FPLC using a Mono S column (Amersham Pharmacia). Cyt c concentration was determined by using an extinction coefficient of 106,100 liters͞ mol-cm at 410 nm (21). Solutions of urea and urea-d 4 (highest quality available, Aldrich) were prepared in 50 mM sodium phosphate in H 2 O (with 10% D 2 O added for lock) or D 2 O, stored at 4°C, and used within 12 h. The uncorrected pH (pH*) of urea solutions was adjusted to 7.0, and the concentration of denaturant was determined by refractive index measurement (22).…”

Section: Methodsmentioning

confidence: 99%