scholarly journals Design of photoactive ruthenium complexes to study electron transfer and proton pumping in cytochrome oxidase

2012 ◽  
Vol 1817 (4) ◽  
pp. 567-574 ◽  
Author(s):  
Bill Durham ◽  
Francis Millett
Keyword(s):  
Electron Transfer ◽  
Cytochrome Oxidase ◽  
Ruthenium Complexes ◽  
Proton Pumping

Effect of diethyl pyrocarbonate modification on spectral and steady-state kinetic properties of bovine heart cytochrome oxidase

1992 ◽  
Vol 70 (7) ◽  
pp. 565-572
Author(s):  
John D. Doran ◽  
Bruce C. Hill
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome Oxidase ◽  
Proton Pumping ◽  
Kinetic Properties ◽  
High Turnover ◽  
Bovine Heart ◽  
Diethyl Pyrocarbonate ◽  
Steady State Kinetic ◽  
State Kinetic

The histidine-specific reagent diethyl pyrocarbonate has been used to chemically modify bovine heart cytochrome oxidase. Thirty-two of sixty-seven histidine residues of cytochrome oxidase are accessible to modification by diethyl pyrocarbonate. Effects on the Soret and α bands of the heme spectrum indicate disturbance in the environment of one or both of the heme groups. However, diethyl pyrocarbonate modification does not alter the 830-nm absorbance band, suggesting that the environment of CuA is unchanged. Maximal modification of cytochrome oxidase by diethyl pyrocarbonate results in loss of 85–90% of the steay-state electron transfer activity, which can be reversed by hydroxylamine treatment. However, modification of the first 20 histidines does not alter either activity or the heme spectrum, but only when 32 residues have been modified are the activity and heme spectral changes complete. The steady-state kinetic profile of fully modified oxidase is monophasic; the phase corresponding to tight cytochrome c binding and low turnover is retained, whereas the high turnover phase is abolished. Proteoliposomes incorporated with modified oxidase have a 65% lower respiratory control ratio and 40% lower proton pumping stoichiometry than liposomes containing unmodified oxidase. These results are discussed in terms of a redox-linked proton pumping model for energy coupling via cytochrome oxidase.Key words: cytochrome oxidase, histidine modification, electron transfer, proton pumping, diethyl pyrocarbonate.

Electron transfer and proton pumping in cytochrome oxidase

Biochimie ◽  
1995 ◽  
Vol 77 (7-8) ◽  
pp. 668-676 ◽  
Author(s):  
M. Brunori ◽  
M.T. Wilson
Keyword(s):  
Electron Transfer ◽  
Cytochrome Oxidase ◽  
Proton Pumping

Theoretical Study of the Energetics of Proton Pumping and Oxygen Reduction in Cytochrome Oxidase

2003 ◽  
Vol 107 (39) ◽  
pp. 10946-10955 ◽  
Author(s):  
Per E. M. Siegbahn ◽  
Margareta R. A. Blomberg ◽  
Mattias L. Blomberg
Keyword(s):  
Oxygen Reduction ◽  
Cytochrome Oxidase ◽  
Theoretical Study ◽  
Proton Pumping

scholarly journals Effects of electron transfer on the stability of hydrogen bonds

2017 ◽  
Vol 8 (11) ◽  
pp. 7324-7329 ◽  
Author(s):  
Tyler M. Porter ◽  
Gavin P. Heim ◽  
Clifford P. Kubiak
Keyword(s):  
Electron Transfer ◽  
Hydrogen Bonds ◽  
Ruthenium Complexes ◽  
Complementary Pair ◽  
Redox States ◽  
The Stability ◽  
Hydrogen Bonded

The measurement of the dimerization constants of hydrogen-bonded ruthenium complexes (12, 22, 32) linked by a self-complementary pair of 4-pyridylcarboxylic acid ligands in different redox states is reported.

scholarly journals Mutation of a single residue in the ba3 oxidase specifically impairs protonation of the pump site

2015 ◽  
Vol 112 (11) ◽  
pp. 3397-3402 ◽  
Author(s):  
Christoph von Ballmoos ◽  
Nathalie Gonska ◽  
Peter Lachmann ◽  
Robert B. Gennis ◽  
Pia Ädelroth ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Time Constant ◽  
Thermus Thermophilus ◽  
Proton Translocation ◽  
Proton Pumping ◽  
Wild Type ◽  
Structural Variant ◽  
In The Wild ◽  
Membrane Bound ◽  
Proton Uptake

The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound protein complex that couples electron transfer to O2 to proton translocation across the membrane. To elucidate the mechanism of the redox-driven proton pumping, we investigated the kinetics of electron and proton transfer in a structural variant of the ba3 oxidase where a putative “pump site” was modified by replacement of Asp372 by Ile. In this structural variant, proton pumping was uncoupled from internal electron transfer and O2 reduction. The results from our studies show that proton uptake to the pump site (time constant ∼65 μs in the wild-type cytochrome c oxidase) was impaired in the Asp372Ile variant. Furthermore, a reaction step that in the wild-type cytochrome c oxidase is linked to simultaneous proton uptake and release with a time constant of ∼1.2 ms was slowed to ∼8.4 ms, and in Asp372Ile was only associated with proton uptake to the catalytic site. These data identify reaction steps that are associated with protonation and deprotonation of the pump site, and point to the area around Asp372 as the location of this site in the ba3 cytochrome c oxidase.

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