The active site structure ofba3 oxidase fromThermus thermophilus studied by resonance Raman spectroscopy

Gerscher, S.; Hildebrandt, Peter; Buse, Gerhard; Soulimane, Tewfik

doi:10.1002/(sici)1520-6343(1999)5:5+<s53::aid-bspy6>3.0.co;2-2

Cited by 20 publications

(12 citation statements)

References 32 publications

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“…It probes the cofactors and their environment, but information on the polypeptide backbone is often lost. In the case of heme proteins, for instance, the excitation can be performed in the Soret band or in the alpha-band region of hemes. ,− The vibrational signals of hemes (see Table ) are then selectively enhanced, so direct information on the ligation and spin state of the porphyrin can be obtained. Iron–sulfur proteins can be excited in the S → Fe charge transfer band region, which enhances the bridging and terminal Fe–S metal ligand vibration bands in the 450–200 cm –1 range.…”

Section: Electrochemical Methodsmentioning

confidence: 99%

Redox Properties of the Membrane Proteins from the Respiratory Chain

Melin

Hellwig

2020

Chem. Rev.

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This review focuses on the electrochemical and spectroelectrochemical studies that gave insight into redox potentials of the four mitochondrial complexes and their homologues from bacterial respiratory chains using O2 as a terminal acceptor, thus providing crucial information about their reaction mechanism. Advantages and limitations of the use of the different techniques for the study of membrane proteins are presented. Electrocatalytic experiments are described that revealed specific features of the reaction with the substrates and inhibitors. An overview is given on the great variability of the redox and catalytic properties of the enzymes in different organisms that may be due to adaptation to the specific environments in which these enzymes function. The adaptation of the redox chain to the different types of quinone and substrates is analyzed, and future studies are discussed.

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Section: Electrochemical Methodsmentioning

confidence: 99%

Redox Properties of the Membrane Proteins from the Respiratory Chain

Melin

Hellwig

2020

Chem. Rev.

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“…Instead, the region around the exposed heme edge is shielded by an additional more unpolar peptide segment which is suggested to increase the thermostability of the protein . Hence, interactions with the ba 3 -oxidase may be qualitatively different compared to other eukaryotic and prokaryotic Cyt- c /CcO redox couples and may account for the high specificity of the Cyt- c 552 / ba 3 -oxidase reaction. − Thus, a detailed analysis of the interfacial redox process of Cyt- c 552 , which is the goal of the present study, promises to elucidate the differences and similarities of the biological electron-transfer mechanism compared to Cyt- c .…”

Section: Introductionmentioning

confidence: 92%

Dynamics of the Heterogeneous Electron-Transfer Reaction of Cytochrome c₅₅₂ from Thermus thermophilus. A Time-Resolved Surface-Enhanced Resonance Raman Spectroscopic Study

1999

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The heterogeneous electron-transfer process of cytochrome c 552 (Cyt-c 552) adsorbed on an Ag electrode was studied by surface-enhanced resonance Raman (SERR) spectroscopy. Upon adsorption the heme protein Cyt-c 552, which acts as an electron carrier in the respiratory chain of Thermus thermophilus, exists in a potential-dependent equilibrium between two conformational states (B1, B2) similar to cytochrome c (Cyt-c) (Wackerbarth et al. Appl. Spectrosc. 1999, 53, 283). From the stationary SERR spectra measured as a function of the potential, the apparent redox potential of state B1 was determined to be −0.044 V (versus saturated calomel electrode) which is 31 mV more negative than the redox potential of Cyt-c 552 in solution. On the basis of a model for the interfacial potential distribution that accounts for the potential drop at the redox site of the adsorbed protein, it is concluded that the true redox potential of the adsorbed state B1 is the same as that for the heme protein in solution. This conclusion is consistent with the structural identity of state B1 and Cyt-c 552 in solution that is derived from the comparison of the SERR and resonance Raman spectra. On the other hand, the formation of B2 is associated with substantial structural changes of the heme pocket and a large negative shift of the redox potential. The dynamics of the heterogeneous reduction of B1 was studied by time-resolved SERR spectroscopy which combines the spectroscopic measurements with the potential jump technique. In contrast to Cyt-c, the electron transfer was found to be much faster than the conformational transition to B2 so that the data could be analyzed on the basis of a one-step relaxation process. For the formal unimolecular electron-transfer rate constant a value of 4.6 s-1 was obtained. On the basis of the rate constants measured as a function of the overpotential, the reorganization energy was determined to be 0.15 eV. This unusually low value may be due to a strongly diminished contribution of the solvent reorientation for the adsorbed species and the specific heme pocket structure of Cyt-c 552 optimized for the electron-transfer reaction. The differences in the electron-transfer mechanism and dynamics compared to Cyt-c are obviously related to the unique structural properties of Cyt-c 552 which may be the consequence of the adaptation to the extreme living conditions of the thermophilic bacterium.

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“…2A). In Thermus ba 3 oxidase, the highspin heme a 3 has its Soret band at 442 nm (26,27). The 452 nm absorption in Cox2 was also assigned to arise from a high-spin heme a 3 , but the corresponding alpha band (∼600 nm) was not detected in spectra of dithionite-reduced Cox2 and of the dithionite-reduced supercomplex.…”

Section: Purification and Identification Of Subunits By Mass Spectrommentioning

confidence: 98%

Heme-copper terminal oxidase using both cytochrome c and ubiquinol as electron donors

Gao

Meyer

Sokolova

et al. 2012

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

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The cytochrome c oxidase Cox2 has been purified from native membranes of the hyperthermophilic eubacterium Aquifex aeolicus . It is a cytochrome ba 3 oxidase belonging to the family B of the heme-copper containing terminal oxidases. It consists of three subunits, subunit I (CoxA2, 63.9 kDa), subunit II (CoxB2, 16.8 kDa), and an additional subunit IIa of 5.2 kDa. Surprisingly it is able to oxidize both reduced cytochrome c and ubiquinol in a cyanide sensitive manner. Cox2 is part of a respiratory chain supercomplex. This supercomplex contains the fully assembled cytochrome bc 1 complex and Cox2. Although direct ubiquinol oxidation by Cox2 conserves less energy than ubiquinol oxidation by the cytochrome bc 1 complex followed by cytochrome c oxidation by a cytochrome c oxidase, ubiquinol oxidation by Cox2 is of advantage when all ubiquinone would be completely reduced to ubiquinol, e.g., by the sulfide∶quinone oxidoreductase, because the cytochrome bc 1 complex requires the presence of ubiquinone to function according to the Q-cycle mechanism. In the case that all ubiquinone has been reduced to ubiquinol its reoxidation by Cox2 will enable the cytochrome bc 1 complex to resume working.

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The active site structure ofba3 oxidase fromThermus thermophilus studied by resonance Raman spectroscopy

Cited by 20 publications

References 32 publications

Redox Properties of the Membrane Proteins from the Respiratory Chain

Redox Properties of the Membrane Proteins from the Respiratory Chain

Dynamics of the Heterogeneous Electron-Transfer Reaction of Cytochrome c₅₅₂ from Thermus thermophilus. A Time-Resolved Surface-Enhanced Resonance Raman Spectroscopic Study

Heme-copper terminal oxidase using both cytochrome c and ubiquinol as electron donors

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The active site structure ofba3 oxidase fromThermus thermophilus studied by resonance Raman spectroscopy

Cited by 20 publications

References 32 publications

Redox Properties of the Membrane Proteins from the Respiratory Chain

Redox Properties of the Membrane Proteins from the Respiratory Chain

Dynamics of the Heterogeneous Electron-Transfer Reaction of Cytochrome c552 from Thermus thermophilus. A Time-Resolved Surface-Enhanced Resonance Raman Spectroscopic Study

Heme-copper terminal oxidase using both cytochrome c and ubiquinol as electron donors

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Dynamics of the Heterogeneous Electron-Transfer Reaction of Cytochrome c₅₅₂ from Thermus thermophilus. A Time-Resolved Surface-Enhanced Resonance Raman Spectroscopic Study