Tag Archives: cytochromes

Activity of respiratory chain cytochrome complexes and cytochromes content in the rat kidney mitochondria under different nutrients content in a diet

H. P. Kopylchuk, O. M. Voloshchuk*

Educational and Scientific Institute of Biology, Chemistry and Natural Resources,
Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine;
*e-mail: o.voloschuk@chnu.edu.ua

Received: 07 February 2023; Revised: 17 March 2023;
Accepted: 13 April 2023; Available on-line: 27 April 2023

An important role in ensuring the functioning of the respiratory chain belongs to the cytochrome part, which includes complexes III (ubiquinol-cytochrome c oxidoreductase) and IV (cytochrome c oxidase). The key components of these enzymatic complexes are heme-containing cytochromes, the number of which depends on the balance of heme synthesis and catabolism. δ-Aminolevulinate synthase catalyzes the first step of the heme biosynthetic pathway, while heme oxygenase is the key enzyme of heme degradation. It is known that nutritional imbalances drive many risk factors for chronic kidney disease. That is why our research aimed to study the activity of ubiquinol-cytochrome c oxidoreductase and cytochrome oxidase complexes, the level of cytochromes a+a3, b, c, and c1, and the activity of key enzymes of heme metabolism in the mitochondria of rat kidneys under conditions of different content of protein and sucrose in animal diet. The obtained results showed a decreased activity of ubiquinol-cytochrome c oxidoreductase and cytochrome oxidase complexes and reduced levels of mitochondria cytochromes a+a3, b, c, and c1 in the kidney mitochondria under the conditions of nutrient imbalance, with the most pronounced changes found in animals kept on a low-protein/high-sucrose diet. A decrease in δ-aminolevulinate synthase activity with a simultaneous 2-fold increase in heme oxygenase activity was found in kidney mitochondria of animals kept on a low-protein/high-sucrose diet compared to those kept on full-value diet indicating an intensification of heme catabolism along with inhibition of its synthesis. The obtained results testify the energy imbalance under the conditions of low-protein/high-sucrose which in turn can lead to the progression of kidney injury.

Activity of NAD•H-generating enzymes and cytochrome content in mitochondria from rat liver and myocardium under artificial hypobiosis

S. D. Melnychuk, S. V. Khyzhnyak, V. S. Morozova, V. M. Voitsitsky

National University of Life and Environmental Sciences of Ukraine, Kyiv;
e-mail: director@quality.ua

The modification particularities of the structural and functional state of the inner mitochondrial membrane of the rat liver and myocardium were observed in conditions of artificial hypobiosis, which was created using hypoxic and hypercapnic gas medium with a body temperature reduction. Under the artificial hypobiosis the activity of NAD·H-generating enzymes of the Krebs cycle of the liver mitochondria decreases. The established changes of the enzymes activity and cytochromes content of the inner mitochondrial membrane indicate the decrease of the oxidative activity of a respiratory chain, that can be limi­ted on a terminal (cytochrome c oxidase) site and leads to the decrease (by 49% at an average) of the H+-ATPase­ activity of the liver mitochondria. Under the artificial hypobiosis the detected increase of the succinate-KoQ-oxidoreductase activi­ty (by 65% at average) causes the maintaining of the functional activity of a mitochondrial respiratory chain, considering the high (relative to control) cytochrome c oxidase and H+-ATPase activities of the mitochondria of the rats’ myocardium. The structural changes of the inner mitochondrial membrane of the liver and myocardium in experimental conditions are accompanied by the increase of hydrophobicity of tryptophan residues microenvironment and the intramolecular modifications of protein molecules.