Biochimica et biophysica acta
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Biochim. Biophys. Acta · Sep 1976
Comparative StudyCopper deficiency and erythrocuprein (2Cu, 2Zn-superoxide dismutase).
The activities of 2Cu,2Zn-superoxide dismutase, ferroxidase (ceruloplasmin), catalase and glutathione peroxidase were measured in the blood of rats during copper depletion. Two control groups of animals were used; one received the regular diet containing all essential components including copper and the other group was maintained on a diet, containing 1% the amount of copper in normal diet, copper being supplied as Cu(Leu)2 in the drinking water. Both groups showed no detectable differences, either in the copper content of blood or in the measured four enzymic activities. ⋯ However, 15 days after the start of the copper depletion catalase activity rises again and reaches the control value on the 40th day and a 30% stimulation was even seen on the 58th day. Upon copper repletion catalase activity reaches 166% of the control within 14 days. No copper-dependent differences of glutathione peroxidase activity were seen regardless whatever copper level was present in the rats.
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Biochim. Biophys. Acta · Jan 1976
Control of long chain fatty acid oxidation in heart mitochondria as studied by spin labeling.
Spin-labeled stearic acid is shown to exhibit the same beta-oxidation kinetics as normal stearic acid. ESR spectra recorded in conditions allowing beta-oxidation indicate that membrane-bound fatty acids can be directly beta-oxidized and that the rate of this reaction depends on the concentration of albumin in the medium. The regulating function of albumin and pool role of the lipidic phase of the mitochondrial membranes are discussed.
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Biochim. Biophys. Acta · Feb 1975
Oxygen consumption of human blood platelets. I. Effect of thrombin.
The effect of thrombin on the oxygen consumption of washed human platelets was measured polarographically with the Clark oxygen electrode. The average basal respiratory rate was 18 plus or minus 1.6 (mean plus or minus S. E.) natoms oxygen per min per 10-9 platelets. ⋯ The thrombin-stimulated increase of oxygen consumption was transient, lasting from 1 to 1.5 min before returning to the respiratory rate observed before the thrombin addition. Release of platelet constituents appeared to precede the stimulation of oxygen consumption. These results may provide a basis for explaining the discrepancy in the literature concerning the effects of thrombin on platelet respiration.
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Biochim. Biophys. Acta · Feb 1975
Oxygen consumption of human blood platelets. II. Effect of inhibitors on thrombin-induced oxygen burst.
The effect of selected inhibitors on the thrombin-stimulated burst and the basal oxygen consumption of washed human platelets were investigated and compared with inhibition of the release reaction. Cyanide (0.2 mM) caused complete inhibition of the basal respiration, but only 15% inhibition of the thrombin-stimulated burst of oxygen consumption. ⋯ N-Ethylmaleimide (0.4 mM) inhibited the release of calcium from platelets by 90%, while prostaglandin E1, acetylsalicylic acid and the above mitochondrial inhibitors caused no more than 30% inhibition of the release reaction. Our results provide evidence that basal respiration and a portion of the thrombin-stimulated burst of oxygen consumption are involved in respiratory chain phosphorylation, and that this component of the thrombin-stimulated burst may be coupled to the maintenance of the release reaction.