Resolution of the electronic transitions of cytochrome c oxidase: evidence for two conformational states of ferrous cytochrome alpha.

Sherman, David H.; Kotake, Susan; Ishibe, N; Copeland, Robert A.

doi:10.1073/pnas.88.10.4265

Cited by 29 publications

(39 citation statements)

References 21 publications

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“…These solvent perturbations do not, however, significantly affect the frequencies of the Raman bands of these molecules when excited under either nonresonance or resonance conditions, although some effect on the Raman intensities has been noted (Copeland & Spiro, 1985;Hildebrandt et al, 1988). By analogy, the differences seen here in the optical spectra of cytochrome a upon complex formajion with cytochrome c, and previously seen between the liganded and unliganded forms of the reduced enzyme (Sherman et al, 1991), could be due to changes in the polarity of the protein environment immediately surrounding the heme. Such polarity changes could be brought about, for example, by movement of a charged amino acid residue or a water molecule (Sassaroli et al, 1989) into proximity with cytochrome a.…”

Section: Discussionsupporting

confidence: 68%

“…We have previously shown that the second derivative absorption spectrum of ferrocytochrome a is sensitive to ligand binding events at cytochrome a3 in the purified bovine enzyme (Copeland, 1991;Sherman et al, 1991). We have further shown that ferrocytochrome c binding affects the second derivative absorption spectrum of bovine cytochrome c oxidase in its cyanide-inhibited forms, but not in its unliganded or CO-inhibited forms (Lynch et al, 1992).…”

Section: Second Derivative Absorption Spectroscopymentioning

confidence: 94%

“…Bovine cardiac and P. denitrificuns cytochrome c oxidase were purified and stored as previously described (Sherman et al, 1991). Horse heart cytochrome c was purchased from Sigma and further purified as described by Brautigan et al (1978).…”

Section: Methodsmentioning

confidence: 99%

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Electronic and vibrational spectroscopy of the cytochrome c: Cytochrome c oxidase complexes from bovine and Paracoccus denitrificans

Lynch¹,

Copeland²

1992

Protein Science

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The 1: 1 complex between horse heart cytochrome c and bovine cytochrome c oxidase, and between yeast cytochrome c and Paracoccus denitrificans cytochrome c oxidase have been studied by a combination of second derivative absorption, circular dichroism (CD), and resonance Raman spectroscopy. The second derivative absorption and CD spectra reveal changes in the electronic transitions of cytochrome a upon complex formation. These results could reflect changes in ground state heme structure or changes in the protein environment surrounding the chromophore that affect either the ground or excited electronic states. The resonance Raman spectrum, on the other hand, reflects the heme structure in the ground electronic state only and shows no significant difference between cytochrome a vibrations in the complex or free enzyme. The only major difference between the Raman spectra of the free enzyme and complex is a broadening of the cytochrome a3 formyl band of the complex that is relieved upon complex dissociation at high ionic strength. These data suggest that the differences observed in the second derivative and CD spectra are the result of changes in the protein environment around cytochrome a that affect the electronic excited state. By analogy to other protein-chromophore systems, we suggest that the energy of the Soret "K* state of cytochrome a may be affected by (1) changes in the local dielectric, possibly brought about by movement of a charged amino acid side chain in proximity to the heme group, or (2) T-"K interactions between the heme and aromatic amino acid residues.

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Section: Discussionsupporting

confidence: 68%

Section: Second Derivative Absorption Spectroscopymentioning

confidence: 94%

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Electronic and vibrational spectroscopy of the cytochrome c: Cytochrome c oxidase complexes from bovine and Paracoccus denitrificans

Lynch¹,

Copeland²

1992

Protein Science

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“…Malmstriim [14] has proposed that two-electron reduction of the initially fully oxidized enzyme alters its conformation in such a way as to facilitate reduction of the a3 Cu, centre. Sherman et al [9], using second-derivative spectroscopy, suggest that the form of cytochrome a present during the steady state is different from that at full reduction.…”

Section: Introductionmentioning

confidence: 99%

The steady state behaviour of cytochrome c oxidase in proteoliposomes

Nicholls

1993

FEBS Letters

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Electron transfer to oxygen catalysed by cytochrome c oxidase is accompanied by spectral changes at the binuclear a 3CuB centre, both in the soluble enzyme and in membranous systems, indicating spin or ligand state transitions of an iron that remains ferric. The other haem group, cytochrome a, does not change its spectral characteristics significantly during the steady state, but remains partially reduced until anaerobiosis. Cytochrome a 3 is fully oxidized in each of its major steady state forms, and reduced upon anaerobiosis to a single ferrous species. Although cytochrome a is normally the immediate electron donor to the binuclear centre, its redox state does not alter under conditions in which the flux through the enzyme is changing significantly. A second electron transfer pathway to the binuclear centre may therefore exist, possibly one in which direct reduction of the binuclear a 3, CuB centre by CuA occurs. Both cytochrome a and CuA behave as simple electron transfer centres. The energy‐conserving chemistry takes place at the binuclear centre in concert with the four‐electron reduction of molecular oxygen.

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“…Toward this end, we have introduced the use of second derivative absorption spectroscopy as a means of resolving and studying the individual electronic transitions of the 2 heme groups within the protein (Copeland, 1991(Copeland, , 1993Ishibe et al, 1991;Sherman et al, 1991;Lynch & Copeland, 1992;Lynch et al, 1992). During the course of these studies we have discovered a new electronic transition of one of the hemes at ca.…”

Section: J S Felsch Et Aimentioning

confidence: 99%

Probing protein‐cofactor interactions in the terminal oxidases by second derivative spectroscopy: Study of bacterial enzymes with cofactor substitutions and heme a model compounds

Felsch¹,

Horvath²,

Gursky³

et al. 1994

Protein Science

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Second derivative absorption spectra are reported for the aa3-cytochrome c oxidase from bovine cardiac mitochondria, the aq-600 ubiquinol oxidase from Bacillus subtilis, the ba3-cytochrome c oxidase from Thermus thermophilis, and the aco-cytochrome c oxidase from Bacillus YN-2000. Together these enzymes provide a range of cofactor combinations that allow us to unequivocally identify the origin of the 450-nm absorption band of the terminal oxidases as the 6-coordinate low-spin heme, cytochrome a. The spectrum of the aco-cytochrome c oxidase further establishes that the split Soret band of cytochrome a, with features at 443 and 450 nm, is common to all forms of the enzyme containing ferrocytochrome a and does not depend on ligand occupancy at the other heme cofactor as previously suggested. To test the universality of this Soret band splitting for 6-coordinate lowspin heme A systems, we have reconstituted purified heme A with the apo forms of the heme binding proteins, hemopexin, histidine-proline-rich glycoprotein and the H64VIV68H double mutant of human myoglobin. All 3 proteins bound the heme A as a (bis)histidine complex, as judged by optical and resonance Raman spectroscopy.In the ferroheme A forms, none of these proteins displayed evidence of Soret band splitting. Heme A-(bis)imidazole in aqueous detergent solution likewise failed to display Soret band splitting. When the cyanide-inhibited mixedvalence form of the bovine enzyme was partially denatured by chemical or thermal means, the split Soret transition of cytochrome a collapsed into a single band at 443 nm. Taken together these data suggest that the observation of Soret splitting, including a feature at 450 nm, results from specific protein-cofactor interactions that are unique to the cytochrome a-binding pocket of the terminal oxidases. The conservation of this unique binding pocket among evolutionarily distant species may reflect some mechanistic significance for this structure.

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Resolution of the electronic transitions of cytochrome c oxidase: evidence for two conformational states of ferrous cytochrome alpha.

Abstract: Second-derivative absorption spectra are re-

Cited by 29 publications

References 21 publications

Electronic and vibrational spectroscopy of the cytochrome c: Cytochrome c oxidase complexes from bovine and Paracoccus denitrificans

Electronic and vibrational spectroscopy of the cytochrome c: Cytochrome c oxidase complexes from bovine and Paracoccus denitrificans

The steady state behaviour of cytochrome c oxidase in proteoliposomes

Probing protein‐cofactor interactions in the terminal oxidases by second derivative spectroscopy: Study of bacterial enzymes with cofactor substitutions and heme a model compounds

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