scholarly journals The Estimation of Cytochrome C Oxidase in Animal Tissues

1948 ◽  
Vol 1 (1) ◽  
pp. 139 ◽  
Author(s):  
TAF Quinlan-Watson ◽  
DW Dewey
Keyword(s):  
Absorption Spectrum ◽  
Cytochrome C ◽  
Oxygen Uptake ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Rate Of Change ◽  
Animal Tissues ◽  
Large Excess ◽  
Spectrophotometric Measurement

Method for the stimation of cytochrom, c oxidase are dependent eitherupon the change which occurs in the absorption spectrum of cytochrome c whenit is oxidized by cytochrome oxidase (Altschul, Abrams, and Hogness 1939;Albaum, Tepperman and Bodansky 1946a, 1946b), or upon the absorption ofgaseous oxyen by, a !!ysten. which consists essentially of a preparation of cytochromeoX~,�Jase in the. pz:esence of a large excess of reduced cytochrome c. Ineither case, it is the rate of oxidation of reduced cytochrome c which is es~imated;in the former by spectrophotometric measurement of the rate of change in lighttransmission . at two different wllyelengths; and, in the latter by manometricestimation of the rate of oxygen uptake (Keilin and Hartree 1938; Stotz 1939;Schneider and Potter 1943). The rate of oxidation of the reduced cytochrome c . , ,"is proportional, under. certain, conditions, to the amount of cytochrome oxidasepresent, apd so. can be used as a measure of ~he activity' of cytochrome oxidase .itself.

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.

scholarly journals Oxidative phosphorylation during glycollate metabolism in mitochondria from phototrophic Euglena gracilis

1975 ◽  
Vol 150 (3) ◽  
pp. 373-377 ◽  
Author(s):  
N Collins ◽  
R H Brown ◽  
M J Merrett
Keyword(s):  
Cytochrome C ◽  
Oxygen Uptake ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Electron Acceptor ◽  
Euglena Gracilis ◽  
Gradient Centrifugation ◽  
Antimycin A ◽  
Isolated Mitochondria ◽  
Glycollate Dehydrogenase

Mitochondria were isolated by gradient centrifugation on linear sucrose gradients from broken cell suspensions of phototrophically grown Euglena gracilis. An antimycin A-sensitive but rotenone-insensitive glycollate-dependent oxygen uptake was demonstrated in isolated mitochondria. The partial reactions of glycollate-cytochrome c oxidoreductase and cytochrome c oxidase were demonstrated by using Euglena cytochrome c as exogenous electron acceptor/donor. Isolated mitochondria contain glycollate dehydrogenase and glyoxylate-glutamate aminotransferase and oxidize exogenous glycine. A P:O ratio of 1.7 was obtained for glycollate oxidation, consistent with glycollate electrons entering the Euglena respiratory chain at the flavoprotein level. The significance of these results is discussed in relation to photorespiration in algae.

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.

scholarly journals Pulsed cytochrome c oxidase from the thermophilic bacterium PS3

1984 ◽  
Vol 223 (3) ◽  
pp. 809-813 ◽  
Author(s):  
N Sone ◽  
A Naqui ◽  
C Kumar ◽  
B Chance
Keyword(s):  
Enzyme Activity ◽  
Absorption Spectrum ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Thermophilic Bacterium ◽  
Decay Process ◽  
Mitochondrial Enzyme ◽  
Bovine Heart ◽  
Enhanced Activity

A caa3-type terminal cytochrome c oxidase (EC 1.9.3.1) from the thermophilic bacterium PS3 containing three subunits showed conversion from resting into pulsed form. Upon pulsing (reduction and re-oxidation), the cytochrome c oxidase activity increased over 10-fold. This enhanced activity of the pulsed enzyme gradually decayed. Addition of phospholipids, necessary for the enzyme activity, did not affect this decay process. Small changes in the absorption spectrum were observed for the resting-into-pulsed transition and for H2O2 ligation to the pulsed enzyme. The e.p.r. spectrum of the resting enzyme was very similar to that of mitochondrial enzyme, but the transient g = 5, 1.78 and 1.69 set of e.p.r. signals, associated with the pulsed bovine heart oxidase, were not observed in the case of pulsed bacterium-PS3 enzyme.

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