Biochemical and biophysical studies on cytochrome aa3

Nicholls, Peter; Buuren, K.J.H. van; Gelder, B.F. Van

doi:10.1016/0005-2728(72)90208-3

Cited by 85 publications

(28 citation statements)

References 16 publications

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“…Enzyme inhibition following the addition of ONOO Ϫ was calculated from the change in the cytochrome c redox state. This is proportional to enzyme turnover under these conditions (23).…”

Section: Methodsmentioning

confidence: 99%

Interaction of Peroxynitrite with Mitochondrial Cytochrome Oxidase

Sharpe

Cooper

1998

Journal of Biological Chemistry

125

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Purified mitochondrial cytochrome c oxidase catalyzes the conversion of peroxynitrite to nitric oxide (NO). This reaction is cyanide-sensitive, indicating that the binuclear heme a 3 /Cu B center is the catalytic site. NO production causes a reversible inhibition of turnover, characterized by formation of the cytochrome a 3 nitrosyl complex. In addition, peroxynitrite causes irreversible inhibition of cytochrome oxidase, characterized by a decreased V max and a raised K m for oxygen. Under these conditions, the redox state of cytochrome a is elevated, indicating inhibition of electron transfer and/or oxygen reduction reactions subsequent to this center. The lipid bilayer is no barrier to these peroxynitrite effects, as NO production and irreversible enzyme inhibition were also observed in cytochrome oxidase proteoliposomes. Addition of 50 M peroxynitrite to 10 M fully oxidized enzyme induced spectral changes characteristic of the formation of ferryl cytochrome a 3 , partial reduction of cytochrome a, and irreversible damage to the Cu A site. Higher concentrations of peroxynitrite (250 M) cause heme degradation. In the fully reduced enzyme, peroxynitrite causes a red shift in the optical spectrum of both cytochromes a and a 3 , resulting in a symmetrical peak in the visible region. Therefore, peroxynitrite can both modify and degrade the metal centers of cytochrome oxidase.

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“…Enzyme inhibition following the addition of ONOO Ϫ was calculated from the change in the cytochrome c redox state. This is proportional to enzyme turnover under these conditions (23).…”

Section: Methodsmentioning

confidence: 99%

Interaction of Peroxynitrite with Mitochondrial Cytochrome Oxidase

Sharpe

Cooper

1998

Journal of Biological Chemistry

125

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“…[4,5] Although most work on the cyano derivatives of hemes, including much early work,[6] − [11] utilized solution measurements, these cyano species can be prepared as solid species and characterized. Thus Scheidt and co-workers prepared and determined the X-ray structures of [Fe(TPP) (CN) 2 ] − [12] as the potassium acetone solvate salt, [13] and two mixed derivatives, [Fe(TPP)(CN)(Py)] [14] and [Fe(OEP)(CN)(Py)].…”

Section: Introductionmentioning

confidence: 99%

New Insights on the Electronic and Molecular Structure of Cyanide-Ligated Iron(III) Porphyrinates

Noll

Schulz

et al. 2007

Inorg. Chem.

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The preparation and characterization of several new cyanoligated six-coordinate low-spin iron(III) porphyrinates are reported. The synthesis and structure of the new bis(cyanide) derivative K(222)] [Fe(TMP)(CN) 2 ] (TMP= tetramesitylporphyrinate) is described. Three mixed-ligand species of the general form [Fe(Porph)(CN)(L)], where L = 1-methylimidazole or pyridine, have also been prepared and structurally characterized. All complexes have been studied with EPR spectroscopy in frozen solution and in microcrystalline form. In some cases, especially those of the bis(cyanide) derivative above and the previously reported [Fe(TPP)(CN) 2 ] − , there are significant differences in the EPR spectra as a result of the state change. These spectral differences can be correlated with changes in the electron configuration that are the likely result of a differing environment of the coordinated cyanide ligands; core conformation and electronic structure of the porphyrin ligand are unlikely to play a role. All four new complexes and [Fe(TPP)(CN) 2 ] − have been studied by Mössbauer spectroscopy with variable temperature and applied magnetic field measurements. The sign of the quadrupole splitting value has been established as negative. These measurements have allowed us to give estimates of the energy difference between the two close-lying d π (d xz and d yz ) orbitals. These splitting values range from ∼267 cm −1 for [Fe(TPP)(CN) 2 ] − to ∼614 cm −1 for [Fe(TPP)(CN)(Py)].

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“…The diameter of the beef CcO is approximately 80 Å based on its crystal structure [58,59], which yields 8.0 · 10 10 CcO molecules on the surface of the modified electrode (geometric area of 0.2 cm 2 ). From the change in current response that results from injection of ferrocytochrome c before and after KCN treatment (assuming one cyanide binding site per CcO) [29,[42][43][44], the number of cytochrome oxidase-CN À complexes on the electrode surface were estimated to be 1.1 · 10 10 and 4.6 · 10 10 for 10 and 30 min exposures to KCN, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Cyanide is a potent inhibitor of CcO because it blocks the reduction of molecular oxygen (i.e., the native function of the oxidase) [29,[40][41][42][43][44]. Previous work suggests that binding of cyanide to the oxidase has 1:1 stoichiometry [42][43][44][45] and that it initially binds to the Cu B site [40].…”

Section: Introductionmentioning

confidence: 99%

“…Previous work suggests that binding of cyanide to the oxidase has 1:1 stoichiometry [42][43][44][45] and that it initially binds to the Cu B site [40]. Although there have been numerous thermodynamic and kinetic studies of cyanide binding to CcO, the effect that cyanide has on the oxidation of ferrocytochrome c and electroreduction of oxygen at oxidasemodified electrodes has not been determined.…”

Section: Introductionmentioning

confidence: 99%

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