Redox reactions in mixed‐valence cytochrome <i>c</i> oxidase

Boelens, Rolf; Wever, Ron

doi:10.1016/0014-5793(80)80649-1

Cited by 24 publications

(7 citation statements)

References 21 publications

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“…Two lines of evidence suggest that one Cu in cytochrome ba3 is essentially identical with the CUA of eukaryotic and bacterial cytochrome aa3: First, the oxidized protein exhibits a weak absorption band at =800 nm that disappears on reduction. A similar band has been observed in other oxidases, where it is thought to arise from CUA2+ (20,(23)(24)(25). Second, the oxidized protein shows an EPR spectrum substantially similar to that of CUA in several other cytochromes aa3 (20,26).…”

mentioning

confidence: 64%

Properties of a copper-containing cytochrome ba3: a second terminal oxidase from the extreme thermophile Thermus thermophilus.

Zimmermann

Nitsche

Fee

et al. 1988

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

135

138

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We describe an alternate terminal oxidase found in the plasma membrane of Thermus thermophilus and designate it cytochrome ba3. The enzyme consists of a single -:35-kDa polypeptide that binds one heme B molecule, one heme A molecule, and two Cu ions. Optical spectra suggest the presence of cytochrome b, cytochrome a3, and CUA in this protein. Quantitative EPR and Mdssbauer studies of the oxidized protein indicate the presence of one low-spin ferric heme, which is assigned to cytochrome b. Mossbauer studies of the reduced protein show the presence of one low-spin ferrous heme, assigned to cytochrome b, and a predominant high-spin ferrous heme that reacts quantitatively with CO to yield an additional low-spin ferrous heme. The latter Fe atom is associated with the heme A and is designated cytochrome a3. The EPR spectrum of the oxidized protein also reveals the presence of a CuA-type center that accounts for half the total Cu. The remainder of the Cu would appear to be present as CUB that is magnetically coupled to the heme A. Amino acid analyses of cytochrome ba3 show the presence of eight to nine histidine residues and one cysteine residue.

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mentioning

confidence: 64%

Properties of a copper-containing cytochrome ba3: a second terminal oxidase from the extreme thermophile Thermus thermophilus.

Zimmermann

Nitsche

Fee

et al. 1988

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

135

138

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“… Redox site or reaction Δε mM −1 cm −1 wavelength (nm) Reference Cyt c O-CO-Cyt c O 67 445 33 cyt. c 21.1 550 46 Cu A 2.3 830 47 1.6 34 heme a 3 112 445 33 82.3 444 32 heme a 57 445 33 66.4 446 32 heme a 20.5 605 33 18.6 32 heme a 3 4.8 605 33 4.6 32 …”

Section: Resultsmentioning

confidence: 99%

The electron distribution in the “activated” state of cytochrome c oxidase

Vilhjálmsdóttir

Gennis

Brzezinski

2018

Sci Rep

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Cytochrome c oxidase catalyzes reduction of O2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O2 reduced to water. The free energy associated with electron transfer to the catalytic site is unequal for the four electron-transfer events. Most notably, the free energy associated with reduction of the catalytic site in the oxidized cytochrome c oxidase (state O) is not sufficient for proton pumping across the energized membrane. Yet, this electron transfer is mechanistically linked to proton pumping. To resolve this apparent discrepancy, a high-energy oxidized state (denoted OH) was postulated and suggested to be populated only during catalytic turnover. The difference between states O and OH was suggested to be manifested in an elevated midpoint potential of CuB in the latter. This proposal predicts that one-electron reduction of cytochrome c oxidase after its oxidation would yield re-reduction of essentially only CuB. Here, we investigated this process and found ~5% and ~6% reduction of heme a3 and CuB, respectively, i.e. the apparent redox potentials for heme a3 and CuB are lower than that of heme a.

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“…Cytochrome oxidase is known to have an absorption band in this region. 20 However, this second-derivative absorption peak is not likely to be from cytochrom e oxidase since it does not correspond to an absorption peak in the original spectra. In addition, it is present in samples that should not contain any cytochrome oxidase, i.e., puri® ed myoglobin in dairy half and half.…”

Section: Metho Dsmentioning

confidence: 97%

Optical Spectroscopic Method for in vivo Measurement of Cardiac Myoglobin Oxygen Saturation

et al. 1999

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A fiber-optic-based spectrophotometer was developed to acquire optical reflectance spectra from a living dog heart. A bullseye concentric optical probe with a 3 mm source-to-detector fiber separation was designed to obtain a 1.5 mm average tissue depth of light penetration. Spectra were analyzed in the near-infrared region from 660 to 840 nm. Myoglobin oxygen saturation was determined by partial least-squares analysis using a calibration spectral data set developed in vitro. Comparison of in vivo and in vitro spectra by Mahalanobis distance and residual ratio tests demonstrated good similarity, justifying use of partial least-squares analysis. Coronary perfusion with an oxygenated blood substitute, Fluosol®, was used to demonstrate that hemoglobin had little effect on the analysis. An increase in myoglobin saturation of 5% was noted when the animals were changed from inspired room air to 100% oxygen. Occlusion of the coronary artery resulted in prompt decrease in myoglobin saturation, and release of the occlusion was followed by rapid increase in saturation to a value above baseline. These experiments demonstrate that it is feasible to use partial least-squares analysis of near-infrared reflectance spectra to determine myoglobin saturation in the blood-perfused, beating heart.

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Redox reactions in mixed‐valence cytochrome c oxidase

Cited by 24 publications

References 21 publications

Properties of a copper-containing cytochrome ba3: a second terminal oxidase from the extreme thermophile Thermus thermophilus.

Properties of a copper-containing cytochrome ba3: a second terminal oxidase from the extreme thermophile Thermus thermophilus.

The electron distribution in the “activated” state of cytochrome c oxidase

Optical Spectroscopic Method for in vivo Measurement of Cardiac Myoglobin Oxygen Saturation

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