scholarly journals The mitochondrial oxidation of quinol monophosphates

1970 ◽  
Vol 118 (5) ◽  
pp. 719-731
Author(s):  
J. M. Young
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Oxygen Uptake ◽  
Cytochrome Oxidase ◽  
Rat Liver ◽  
Mode Of Action ◽  
Electron Transport Chain ◽  
Rapid Reduction ◽  
Transport Chain ◽  
Mitochondrial Oxidation

1. Mitochondria from ox heart and rat liver catalysed a slow cyanide-sensitive oxidation of 2,3-dimethylnaphthaquinol monophosphate, duroquinol monophosphate, menadiol 1-phosphate and menadiol 4-phosphate. 2. The release of Pi was concomitant with oxygen uptake. 3. The oxidation was somewhat stimulated by Ca2+ and Pi, and weakly inhibited by 2,4-dinitrophenol. 4. The quinol monophosphates effected a rapid reduction of free cytochrome c, and consequently addition of cytochrome c greatly increased the rate of the mitochondrial oxidation of 2,3-dimethylnaphthaquinol monophosphate. 5. This quinol phosphate interacts with the electron-transport chain at the level of cytochrome c. 6. Polylysine promoted an interaction between 2,3-dimethylnaphthaquinol monophosphate and cytochrome oxidase. Thus, although polylysine blocks mitochondrial oxidations via reduced cytochrome c, the oxidation of the quinol phosphate was strongly stimulated. 7. This stimulation was most effective in the most intact mitochondrial preparations and was inhibited by ADP and by Pi. 8. The implications of these results for factors limiting the rate of quinol phosphate oxidation, the mode of action of stimulators and the mechanism of Pi formation are discussed.

scholarly journals Effects of L-Malate on Mitochondrial Oxidoreductases in Liver of Aged Rats

2011 ◽  
pp. 329-336 ◽  
Author(s):  
J.-L. WU ◽  
Q.-P. WU ◽  
Y.-P. PENG ◽  
J.-M. ZHANG
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Electron Transport Chain ◽  
Nadh Dehydrogenase ◽  
Tricarboxylic Acid Cycle ◽  
Radical Scavenger ◽  
Aged Rats ◽  
Transport Chain ◽  
Nadh Cytochrome

Accumulation of oxidative damage has been implicated to be a major causative factor in the decline in physiological functions that occur during the aging process. The mitochondrial respiratory chain is a powerful source of reactive oxygen species (ROS), considered as the pathogenic agent of many diseases and aging. L-malate, a tricarboxylic acid cycle intermediate, plays an important role in transporting NADH from cytosol to mitochondria for energy production. Previous studies in our laboratory reported L-malate as a free radical scavenger in aged rats. In the present study we focused on the effect of L-malate on the activities of electron transport chain in young and aged rats. We found that mitochondrial membrane potential (MMP) and the activities of succinate dehydrogenase, NADH-cytochrome c oxidoreductase and cytochrome c oxidase in liver of aged rats were significantly decreased when compared to young control rats. Supplementation of L-malate to aged rats for 30 days slightly increased MMP and improved the activities of NADH-dehydrogenase, NADH-cytochrome c oxidoreductase and cytochrome c oxidase in liver of aged rats when compared with aged control rats. In young rats, L-malate administration increased only the activity of NADH-dehydrogenase. Our result suggested that L-malate could improve the activities of electron transport chain enzymes in aged rats

Toxicity of bile acids on the electron transport chain of isolated rat liver mitochondria

Hepatology ◽  
1994 ◽  
Vol 19 (2) ◽  
pp. 471-479 ◽  
Author(s):  
Stephan Krähenbühl ◽  
Christine Talos ◽  
Sven Fischer ◽  
Jürg Reichen
Keyword(s):  
Electron Transport ◽  
Bile Acids ◽  
Rat Liver ◽  
Electron Transport Chain ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Transport Chain ◽  
Isolated Rat

THE EFFECT OF LETHAL DOSES OF X-IRRADIATION ON THE ENZYMATIC ACTIVITY OF MITOCHONDRIAL CYTOCHROME c

1966 ◽  
Vol 44 (4) ◽  
pp. 433-448 ◽  
Author(s):  
J. F. Scaife
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Electron Transport Chain ◽  
Reductase Activity ◽  
Ehrlich Ascites Carcinoma ◽  
Whole Body ◽  
Triphenyltetrazolium Chloride ◽  
Transport Chain ◽  
Ehrlich Ascites ◽  
X Irradiation

The coupling of the tetrazolium salts triphenyltetrazolium chloride and nitro-blue tetrazolium to the electron transport chain in mitochondria of thymus, spleen, liver, kidney, and Ehrlich ascites carcinoma cells has been studied with several substrates. In experiments on succinate–triphenyltetrazolium chloride reductase activity it has been possible to demonstrate a radiation lesion in the electron transport chain of mitochondria from thymus and spleen, but not in those from other tissues. This lesion is evident 4 hours after 25 rad of whole-body irradiation, or earlier with higher doses. It is not prevented by the prior administration of aminoethylisothiouronium bromide, serotonin, vitamin K1, or vitamin E, but is reduced by anoxic conditions.Lower levels of cytochrome c are found in irradiated mitochondria isolated from thymus, and the radiation lesion is believed to be produced by loosening the binding of cytochrome c to the mitochondrial membrane after X-irradiation. Decreased levels of ATP occur in thymus, spleen, and ascites cells following irradiation.

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