A flash-photolysis study of the reactions of acaa 3-ttype cytochrome oxidase with dioxygen and carbon monoxide

1996 ◽  
Vol 28 (6) ◽  
pp. 495-501 ◽  
Author(s):  
Shun Hirota ◽  
Margareta Svensson-Ek ◽  
Pia Ädelroth ◽  
Nobuhito Sone ◽  
Thomas Nilsson ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome Oxidase ◽  
Flash Photolysis

scholarly journals The reaction of cytochrome oxidase with oxygen in the fission yeast Schizosaccharomyces pombe 972h-. Studies at subzero temperatures and measurement of apparent oxygen affinity

1979 ◽  
Vol 184 (3) ◽  
pp. 555-563 ◽  
Author(s):  
R K Poole ◽  
D Lloyd ◽  
B Chance
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Cytochrome Oxidase ◽  
Flash Photolysis ◽  
Oxygen Affinity ◽  
Intermediate Compound ◽  
Reduced Form ◽  
Difference Spectra ◽  
Intact Cells ◽  
Compound A

1. Cytochrome alpha 3 in whole-cell suspensions of the fission yeast Schizosaccharomyces pombe reacted in the reduced form with CO to give a photodissociable CO complex with absorption maxima at 429, 543 and 591 nm in CO-liganded reduced-minus-reduced difference spectra. 2. Other CO-bound haemoproteins, cytochromes P-420 and P-450, were not photodissociated under the conditions employed. 3. Measurements of the rates of reassociation of CO with cytochrome alpha 3 after flash photolysis over the temperature range from −101 to −109 degrees C gave a value for Eact. of 28.6 kJ/mol. 4. Between −94 and −106 degrees C, O2 reacted with cytochrome oxidase in intact cells to give an oxygenated intermediate (compound A). 5. At −70 degrees C compound A was converted into a second spectrally distinct intermediate (compound B). 6. Electron transport, indicated by the oxidation of cytochromes alpha + alpha 3 and cytochrome c, did not occur until the temperature was raised to −50 degrees C. 7. At room temperature cytochfome oxidase was oxidized to 50% of its steady-state concentration by 0.35 microM-O2.

Flash photolysis of the carbon monoxide compounds of mutant and wild-type cytochrome bo from E. coli

1993 ◽  
Vol 21 (3) ◽  
pp. 259S-259S ◽  
Author(s):  
SIMON BROWN ◽  
JON N. RUMBLEY ◽  
ROBERT B. GENNIS ◽  
PETER R. RICH
Keyword(s):  
Carbon Monoxide ◽  
Flash Photolysis ◽  
Wild Type ◽  
E Coli ◽  
Cytochrome Bo

INHIBITION OF MYOCARDIAL CYTOCHROME OXIDASE FOLLOWING CARBON MONOXIDE EXPOSURE.

2005 ◽  
Vol 33 ◽  
pp. A52
Author(s):  
Kelechi N Iheagwara ◽  
David A Piel ◽  
Richard J Levy ◽  
Clifford S Deutschman ◽  
Stephen R Thom
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome Oxidase

scholarly journals THE EQUILIBRIUM BETWEEN CYTOCHROME OXIDASE AND CARBON MONOXIDE

1957 ◽  
Vol 40 (4) ◽  
pp. 593-608 ◽  
Author(s):  
George Wald ◽  
David W. Allen
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome Oxidase ◽  
Hill Equation ◽  
Bohr Effect ◽  
Degree Of Saturation ◽  
Percentage Saturation ◽  
Equilibrium Function ◽  
Hyperbolic Equilibrium ◽  
High Degree ◽  
The Hill

An evolution argument which attempted to trace the development of hemoglobins from such respiratory pigments as cytochrome oxidase presupposed that the latter possesses, in addition to its high affinity for oxygen, an approximately hyperbolic equilibrium function, and little if any Bohr effect (decline in affinity for oxygen with rise in acidity). Since cytochrome oxidase, unlike hemoglobin, is irreversibly oxidized by oxygen, the present experiments examine its combination with carbon monoxide, with which, like hemoglobin, it yields a true equilibrium. In all known hemoglobins the form of the equilibrium function and the vigor of the Bohr effect are similar with carbon monoxide and with oxygen, so that observations involving the former gas are relevant to the relations of the latter. The equilibrium function of cytochrome oxidase with carbon monoxide—percentage saturation vs. partial pressure of CO—is slightly inflected (in the Hill equation n = 1.26; for a hyperbola, n = 1). No Bohr effect is present in the range of pH 7–8. The pressure of carbon monoxide at which half-saturation occurs (p50) is about 0.17 mm. at 10–13°C. The affinity for carbon monoxide is therefore higher than commonly supposed. These properties are consistent with the evolution argument. They are important also for the physiological functioning of cytochrome oxidase, the nearly hyperbolic equilibrium function facilitating a high degree of saturation, and the lack of Bohr effect making this enzyme impervious to hyperacidity. The slight inflection of the equilibrium function shows that the Fe-porphyrin units of cytochrome oxidase interact to a degree, hence that the enzyme must contain more than one such unit per molecule. It is suggested that in cytochrome oxidase two Fe-porphyrin groups may unite with one oxygen in the manner Fe++-O2-Fe++; and that the evolution of hemoglobins proceeded over a first stage in which the hemes were separated so that each combines with only one molecule of oxygen, so tending to remain reduced; to a further stage in which the separated hemes interact through the protein to facilitate one another in combining with oxygen.

Does carbon monoxide inhibit cytochrome oxidase in vivo?

1997 ◽  
Vol 25 (3) ◽  
pp. 406S-406S
Author(s):  
NATHAN A. DAVIES ◽  
CHRISTOS TRIKKAS ◽  
CHRIS E. COOPER
Keyword(s):  
Carbon Monoxide ◽  
Cytochrome Oxidase

scholarly journals The reaction of Pseudomonas aeruginosa cytochrome c oxidase with carbon monoxide

1975 ◽  
Vol 151 (1) ◽  
pp. 51-59 ◽  
Author(s):  
S R Parr ◽  
M T Wilson ◽  
C Greenwood
Keyword(s):  
Cytochrome Oxidase ◽  
Flash Photolysis ◽  
Order Rate Constant ◽  
Second Order ◽  
Stopped Flow ◽  
First Order ◽  
Order Rate ◽  
Co Concentration ◽  
Pseudo First Order ◽  
Two Phases

The binding of CO to ascorbate-reduced Pseudomonas cytochrome oxidase was investigated by static-titration, stopped-flow and flash-photolytic techniques. Static-titration data indicated that the binding process was non-stoicheiometric, with a Hill number of 1.44. Stopped-flow kinetics obtained on the binding of CO to reduced Pseudomonas cytochrome oxidase were biphasic in form; the faster rate exhibited a linear dependence on CO concentration with a second-order rate constant of 2 × 10(4) M-1-s-1, whereas the slower reaction rapidly reached a pseudo-first-order rate limit at approx. 1s-1. The relative proportions of the two phases observed in stopped-flow experiments also showed a dependency on CO concentration, the slower phase increasing as the CO concentration decreased. The kinetics of CO recombination after flash-photolytic dissociation of the reduced Pseudomonas cytochrome oxidase-CO complex were also biphasic in character, both phases showing a linear pseudo-first-order rate dependence on CO concentration. The second-order rate constants were determined as 3.6 × 10(4)M-1-s-1 and 1.6 × 10(4)M-1-s-1 respectively. Again the relative proportions of the two phases varied with CO concentration, the slower phase predominating at low CO concentrations. CO dissociation from the enzyme-CO complex measured in the presence of O2 and NO indicated the presence of two rates, of the order of 0.03s-1 and 0.15s-1. When sodium dithionite was used as a reducing agent for the Pseudomonas cytochrome oxidase, the CO-combination kinetics observed by both stopped flow and flash photolysis were extremely complex and not able to be simply analysed.

Sign in / Sign up

Export Citation Format

Share Document