Response of Heme Symmetry to the Redox State of Bovine Cytochrome c Oxidase

Biochemistry ◽  
2018 ◽  
Vol 57 (28) ◽  
pp. 4105-4113
Author(s):  
Katarina Kopcova ◽  
Ludmila Blascakova ◽  
Tibor Kozar ◽  
Daniel Jancura ◽  
Marian Fabian
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State

Kinetics of the cytochrome c oxidase and reductase reactions in energized and de-energized mitochondria

1977 ◽  
Vol 55 (7) ◽  
pp. 706-713 ◽  
Author(s):  
Lars Chr. Petersen ◽  
Hans Degn ◽  
Peter Nicholls
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxygen Concentration ◽  
Respiration Rate ◽  
Redox State ◽  
Rat Liver Mitochondria ◽  
Excess Oxygen ◽  
Succinate Oxidation ◽  
State Reduction

1. Coupled, cytochrome-c-depleted ('stripped') rat liver mitochondria reducing oxygen in the presence of exogenous cytochrome c, with succinate or ascorbate as substrates, show marked declines in the steady-state reduction of cytochrome c in excess oxygen on addition of uncouplers. Calculated ratios of maximal turnover in the uncoupled state and in the energized state for the cytochrome c oxidase (EC 1.9.3.1) reaction lie between 3 and 6, as obtained with reconstituted oxidase-containing vesicles. The succinate-cytochrome c reductase activity in such mitochondria shows a smaller response to uncoupler than that of the oxidase.2. The respiration rates of uncoupled mitochondria oxidizing ascorbate in the presence of added cytochrome c follow a Michaelis–Menten relationship with respect to oxygen concentration, in accordance with the pattern found previously with the solubilized oxidase. But succinate oxidation tends to give nonlinear concave-upward double-reciprocal plots of respiration rate against oxygen concentration, in accordance with the pattern found previously with intact uncoupled mitochondria.3. From simultaneous measurements of cytochrome c steady-state reduction, respiration rate, and oxygen concentration during succinate oxidation under uncoupled conditions it is found that at full reduction of cytochrome c, apparent Km for oxygen is 0.9 μM and the maximal oxidase (aa3) turnover is 400 s−1 (pH 7.4, 30 °C).4. The redox state of cytochrome c in uncoupled systems reflects a simple steady state; the redox state of cytochrome c in energized systems tends towards an equilibrium condition with the terminal cytochrome a3, whose apparent potential under these conditions is more negative than that of cytochrome c.

Cat brain cytochrome-c oxidase redox changes induced by hypoxia after blood-fluorocarbon exchange transfusion

1995 ◽  
Vol 269 (2) ◽  
pp. H417-H424 ◽  
Author(s):  
M. Ferrari ◽  
M. A. Williams ◽  
D. A. Wilson ◽  
N. V. Thakor ◽  
R. J. Traystman ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Near Infrared ◽  
Acute Hypoxia ◽  
Nir Spectroscopy ◽  
Severe Reduction ◽  
O2 Concentration ◽  
O2 Delivery ◽  
Sep Monitoring

We used rapid-scanning near-infrared (NIR) spectroscopy (730-960 nm) to study the effects of graded or acute hypoxia on cerebral cytochrome-c oxidase (cyt aa3) redox state in blood-perfluoro-carbon-exchanged cats with somatosensory evoked potential (SEP) monitoring. In graded hypoxia [10 min each at fractional inspiratory O2 concentration (FIO2) 0.9, 0.8, 0.7, 0.6, and 0.5], cyt aa3 reduction occurred at FIO2 0.6 when cerebral O2 delivery was < 3.5 ml.100 g-1.min-1. In acute hypoxia (FIO2 0.6 for 10 min), significant cyt aa3 reduction occurred from 5 to 10 min (cerebral O2 delivery 3.1 +/- 0.3 ml.100 g-1.min-1) and recovered with reoxygenation (FIO2 1.0). Cyt aa3 redox changes preceded or coincided with SEP alterations in both hypoxia protocols. These results demonstrate that cerebral cyt aa3 reduction occurs with severe reduction of cerebral O2 delivery, but no significant change in cerebral cyt aa3 redox state occurs with small reductions of cerebral O2 delivery. We conclude that substantial changes in cerebral cyt aa3 do not occur at physiological levels of O2 delivery and that current NIR clinical instruments would detect oxygen-dependent cerebral cyt aa3 redox changes only when O2 delivery is extremely compromised.

Reduction of cytochrome-c oxidase copper precedes failing cerebral O2 utilization in fluorocarbon-perfused cats

1996 ◽  
Vol 271 (2) ◽  
pp. H579-H587 ◽  
Author(s):  
R. Stingele ◽  
B. Wagner ◽  
M. V. Kameneva ◽  
M. A. Williams ◽  
D. A. Wilson ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Near Infrared ◽  
Hypoxic Conditions ◽  
Sagittal Sinus ◽  
Tissue Po2 ◽  
Relationship Of ◽  
The Relationship

We determined the relationship of the low-potential copper (CuA) redox state of cytochrome-c oxidase to the brain tissue PO2 (PtiO2) and global cerebral O2 consumption (CMRO2) in vivo. The redox state of cytochrome-c oxidase copper was monitored in perfluorocarbon-exchanged cats under normoxic and graded hypoxic conditions with use of near-infrared spectroscopy. Continuous spectra ranging from 730 to 960 nm were acquired, and the change in copper redox state was assessed by the absorption changes at 830 nm. PtiO2 was measured with O2-sensitive electrodes implanted into the cortex, and CMRO2 was determined by sampling arterial and superior sagittal sinus perfusate and by measuring blood flow with radiolabeled microspheres. As PtiO2 decreased with hypoxia, the CuA of cytochrome-c oxidase became progressively reduced, whereas the CMRO2 was unchanged during the initial stages of hypoxia. Only with severe hypoxia, did CMRO2 and the amplitude of somatosensory evoked potentials decrease. We conclude that the CuA site of cytochrome-c oxidase is involved in a regulatory adjustment that helps maintain CMRO2 constant.

Control of proteoliposomal cytochrome c oxidase: the partial reactions

1990 ◽  
Vol 68 (9) ◽  
pp. 1135-1141 ◽  
Author(s):  
Peter Nicholls
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Ph Gradient ◽  
Transfer Model ◽  
State Reduction

The steady-state spectroscopic behaviour and the turnover of cytochrome c oxidase incorporated into proteoliposomes have been investigated as functions of membrane potential and pH gradient. The respiration rate is almost linearly dependent on [cytochrome c2+] at high flux, but while the cytochrome a redox state is always dependent on the [cytochrome c2+] steady state, it reaches a maximum reduction level less than 100% in each case. The maximal aerobic steady-state reduction level of cytochrome a is highest in the presence of valinomycin and lowest in the presence of nigericin. The proportion of [cytochrome c2+] required to achieve 50% of maximal reduction of cytochrome a varies with the added ionophores; the apparent redox potential of cytochrome a is most positive in the fully decontrolled system (plus valinomycin and nigericin). At low levels of cytochrome a reduction, the rate of respiration is no longer a linear function of [cytochrome c2+], but is dependent upon the redox state of both cytochromes a and c. That is, proteoliposomal oxidase does not follow Smith–Conrad kinetics at low cytochrome c reduction levels, especially in the controlled states. The control of cytochrome oxidase turnover by ΔpH and by ΔΨ can be explained either by an allosteric model or by a model with reversed electron transfer between the binuclear centre and cytochrome a. Other evidence suggests that the reversed electron transfer model may be the correct one.Key words: proteoliposomes, cytochrome c, cytochrome oxidase, membrane potential, pH gradient, cytochrome a, electron transfer.

Conformational transitions and molecular hysteresis of cytochrome c oxidase: Varying the redox state by electronic wiring

Soft Matter ◽  
2010 ◽  
Vol 6 (21) ◽  
pp. 5523 ◽  
Author(s):  
Christoph Nowak ◽  
Maria Gabriella Santonicola ◽  
Denise Schach ◽  
Jiapeng Zhu ◽  
Robert B. Gennis ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Conformational Transitions

scholarly journals Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy

2014 ◽  
Vol 19 (5) ◽  
pp. 055001 ◽  
Author(s):  
Jangwoen Lee ◽  
Jae G. Kim ◽  
Sari B. Mahon ◽  
David Mukai ◽  
David Yoon ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Optical Spectroscopy ◽  
Redox State ◽  
Diffuse Optical Spectroscopy
Sign in / Sign up

Export Citation Format

Share Document