Cytochrome oxidase and its derivatives. IX. Spectrophotometric studies on the rapid reaction of ferrous cytochrome c oxidase with molecular oxygen under conditions of complete and partial oxygenation

1969 ◽  
Vol 172 (1) ◽  
pp. 37-51 ◽  
Author(s):  
M.V. Gilmour ◽  
M.R. Lemberg ◽  
B. Chance
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Molecular Oxygen ◽  
Rapid Reaction

Cytochrome Oxidase

1969 ◽  
Vol 49 (4) ◽  
pp. 888-888
Author(s):  
M. R. Lemberg
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Molecular Oxygen ◽  
Rapid Reaction

M. R. Lemberg, “Cytochrome Oxidase” Gilmour, Lemberg, and Chance or Lemberg and Chance, unpublished observations, should now be: Gilmour, M. V., M. R. Lemberg, and B. Chance. Cytochrome oxidase and its derivatives. 9. Spectrophotometric studies on the rapid reaction of ferrous cytochrome c oxidase with molecular oxygen under conditions of complete and partial oxygenation. Biochim. Biophys. Acta 172: 37, 1969. Williams, Lemberg, and Cutler, unpublished observations, should now be: Williams, G. R., M. R. Lemberg, and M. E. Cutler. The oxidized forms of cytochrome oxidase. Can. J. Biochem. 46: 1371, 1968. See PDF for Table

Sulphide as an inhibitor and electron donor for the cytochrome c oxidase system

1982 ◽  
Vol 60 (6) ◽  
pp. 613-623 ◽  
Author(s):  
P. Nicholls ◽  
J.-K. Kim
Keyword(s):  
Cytochrome C ◽  
Oxygen Uptake ◽  
Cytochrome C Oxidase ◽  
Submitochondrial Particles ◽  
Inhibitory Interaction ◽  
Cytochromes C ◽  
Subsequent Step ◽  
Oxidase Enzyme ◽  
Rapid Reaction ◽  
The One

Anomalies both kinetic and equilibrium in nature are described for the inhibition of cytochrome c oxidase activity by sulphide in the isolated enzyme and in submitochondrial particles. These anomalies are related to the involvement of more than 1 mol of sulphide in the blockage of one cytochrome aa3 centre. Sulphide reduces resting cytochrome a3, a reaction that results in oxygen uptake and the loss of a sulphide molecule. Sulphide can also reduce cytochromes c and a; in the former case, a part of the one-equivalent oxidation product, presumed to be the SH∙ radical, reacts with oxygen. Such oxygen uptake is also seen under aerobic conditions when ferricyanide reacts with sulphide. Three phases are identified in the inhibitory interaction of sulphide with the cytochrome c oxidase enzyme itself: an initial rapid reaction involving sulphide oxidation, oxygen uptake, and conversion of cytochrome aa3 into the low-spin "oxyferri" form; a subsequent step in which sulphide reduces cytochrome a; and the final inhibitory step in which a third molecule of sulphide binds the a3 iron centre in the cytochrome [Formula: see text] (oxy) species to give cytochrome [Formula: see text]. The initial events parallel some of the events in the interaction of the cytochrome c – cytochrome aa3 system with monothiols; the final inhibitory event resembles that with cyanide.

The Conformational States of Oxidized and Oxygenated Beef-Heart Cytochrome c Oxidase

1975 ◽  
Vol 53 (4) ◽  
pp. 461-466 ◽  
Author(s):  
Jack A. Kornblatt ◽  
D. I. C. Kells ◽  
G. R. Williams
Keyword(s):  
Ascorbic Acid ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Sedimentation Velocity ◽  
Beef Heart ◽  
Conformational States

1. The "oxygenated" form of cytochrome oxidase has been generated by treatment of the enzyme with ascorbic acid.2. "Oxygenated oxidase" so generated is stable over long periods (24 h).3. Sedimentation velocity experiments have shown the "oxygenated oxidase to be a less compact molecule than the oxidized.

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.

scholarly journals Kinetics of inhibition of purified and mitochondrial cytochrome c oxidase by psychosine (β-galactosylsphingosine)

1993 ◽  
Vol 290 (1) ◽  
pp. 139-144 ◽  
Author(s):  
C E Cooper ◽  
M Markus ◽  
S P Seetulsingh ◽  
J M Wrigglesworth
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Slow Phase ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Cytochrome ◽  
Submitochondrial Particles ◽  
Bovine Heart

1. Psychosine (beta-galactosylsphingosine) is the toxic agent in Krabbe's disease (globoid cells leukodystrophy). It inhibits purified bovine heart mitochondrial cytochrome c oxidase; there is a rapid phase of inhibition (complete within 10-15 s) and a slower phase (complete within 10-15 min). Both phases are also seen in rat liver mitochondria. IC50 is about 200 microM psychosine in the purified enzyme and less than 20 microM in mitochondria. Psychosine inhibition is due to binding to cytochrome oxidase, not cytochrome c. 2. Bovine heart submitochondrial particles show inhibition similar to rat liver mitochondria. However, although proteoliposomes containing bovine heart cytochrome oxidase show an identical fast phase, they have no noticeable slow phase of inhibition. Addition of phospholipid liposomes to submitochondrial particles relieved the majority of psychosine inhibition, consistent with the removal of those molecules binding in the slow phase. Psychosine can inhibit cytochrome oxidase molecules facing in either direction in proteoliposomes and submitochondrial particles, suggesting that it can rapidly interact with both sides of a membrane when added externally. 3. At high ionic strength, the presence of psychosine decreases the Vmax. of cytochrome oxidase with little effect on the Km for cytochrome c. This non-competitive inhibition suggests that the psychosine-enzyme complex is kinetically inactive and not labile over the time course of the assay. Psychosine does not inhibit the reduction of haem a or haem a3 by artificial electron donors, but does inhibit the reduction of haem a by cytochrome c.

scholarly journals EPR characterization of ascorbyl and sulfur dioxide anion radicals trapped during the reaction of bovine Cytochrome c Oxidase with molecular oxygen

2010 ◽  
Vol 203 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Michelle A. Yu ◽  
Tsuyoshi Egawa ◽  
Syun-Ru Yeh ◽  
Denis L. Rousseau ◽  
Gary J. Gerfen
Keyword(s):  
Sulfur Dioxide ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Molecular Oxygen ◽  
Anion Radicals
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