Ionol (BHT) produces superoxide anion.

In aqueous medium etiolated wheat seedlings release superoxide anion (O2*-). Interaction of a synthetic antioxidant, butylated hydroxytoluene (BHT, ionol), with oxygen in the aqueous medium is accompanied by O2*- formation. This suggests that under certain conditions BHT behaves as a prooxidant. A natural antioxidant, superoxide dismutase (SOD), and also a wound healing preparation, emulsified denatured placenta (EDP), do not exhibit the prooxidant properties. In contrast to BHT, they reduce O2*- production by the etiolated wheat seedling system.

A new inhibitor of the CoQ-dependent redox reactions in mitochondria and chromatophores.

The effects of 3,4-dimethoxyphenyl-1-amylketone (DPK) on the CoQ-dependent stages of the electron transport systems in mitochondria and Rhodobacter sphaeroides chromatophores were studied. The two systems contain the complete Q-cycle. The sensitivities of the Q-cycles of two electron transport systems to antimycin, myxothiazole, and other inhibitors are virtually indistinguishable from one another, but these systems have different CoQ reduction processes. The dependence of the inhibition extent of the mitochondrial succinate oxidase on the DPK concentration was studied. The effective concentration of DPK is 0.5-2.5 mM. The presence of the point of inflection in the titration curve indicates that there are two mechanisms of inhibition. The effects of DPK on the extent of reduction of cytochromes b and c1 + c in mitochondria as well as on the electrogenic stages of the Q-cycle in chromatophores were examined. The experiments showed that DPK prevents three CoQ-dependent reactions related to the Q-cycle: electron transport between succinate dehydrogenase and the Q-cycle in mitochondria and functioning of the Z (o) and C (i) sites of the Q-cycle in chromatophores. DPK does not affect the electrogenic reaction associated with protonation of the secondary quinone acceptor QB in the reaction center of chromatophores. The mitochondrial NADH-dehydrogenase is inhibited by DPK at lower but comparable concentrations (C50 = 0.2 mM).

[Mitochondrial proteolipids]. / Proteolipidy mitokhondrii.

A convenient procedure is proposed for extracting mitochondrial proteolipids using a single phase mixture chloroform-methanol-water (1:2:0.8 v/v) with subsequent separation of the phases. The proteolipids were concentrated at the interface between the phases and thus purified from the bulk of the phospholipids. It was found that the mitochondrial proteolipids represent stable complexes of phospholipids with some low molecular weight proteins (M(r) = 7-18 kDa). The latter are destroyed at acid pH values. The phospholipid/protein ratio was found to be equal to 6 (assuming the molecular masses of the proteins and phospholipids to be equal to 10 and 0.8 kDa, respectively). The phospholipid composition of the tightly bound proteolipids thus obtained did not differ from that of the mitochondrial phospholipids. Using 31P-NMR, nonbilayer structures were found to arise from proteolipid reconstitution into multibilayer liposomes.

[The effect of inhibitors of the Q-cycle on cyano-resistant oxidation of malate by rat liver mitochondria in the presence of menadione]. / Vliianie ingibitorov Q-tsikla na tsianrezistentnoe okislenie malata mitokhondriiami pecheni krys v prisutstvii menadiona.

Based on the inhibitor analysis data, it has been assumed that the Q-cycle plays a role in the cyano-resistant malate oxidation induced by menadione (90 microM) in rat liver mitochondria. The extent of involvement of Q-cycle transmitters in the cyano-resistant respiration of mitochondria is determined by the mode of the electron supply into the Q-cycle. In the presence of dicumarol, i.e., under conditions when CoQ and menadione are reduced by NADH-quinone reductase, the bulk of the electrons pass through the o-center of the Q-cycle. Myxothiazole inhibits the respiration by 70-80%, while antimycin--by only 20-30%. In the presence of myxothiazole and antimycin menadione oxidizes cytochrome b. In the presence of rotenone, when menadione is reduced by DT-diaphorase, the rate of cyano-resistant respiration decreases approximately twofold; its sensitivity towards myxothiazole and antimycin drops down to 40%. In the absence of rotenone and dicumarol the Q-cycle does not participate in the cyano-resistant respiration which under these conditions is insensitive either to myxothiazole or to antimycin. It is concluded that the mechanism of cyano-resistant respiration changes with an alteration in the rates of quinones K3 and CoQ reduction. The mechanism of cyano-resistant respiration is also controlled by the medium tonicity. A reduction in the medium tonicity decrease the participation of the Q-cycle and, correspondingly, the sensitivity of the cyano-resistant respiration towards myxothiazole and antimycin.

[Interaction of menadione and duroquinone with Q-cycle during DT-diaphorase function]. / Vzaimodeistvie menadiona i durokhinona s Q-tsiklom v usloviiakh rabotyDT-diaforazy

The interaction of quinones (menadione and duroquinone) with DT-diaphorase and mitochondrial electron transport chain translocators at low (120 mosM) and high (400 mosM) values of the medium tonicity in the quinone concentration range of 6-90 microM was studied. It was shown that with a rise in menadione (K3) concentration the number of electron transport carriers interacting with it increase. At K3 concentration of 6 microM the latter is reduced by DT-diaphorase and fully oxidized via the Q-cycle. At K3 concentration of 15 microM the latter is also reduced by DT-diaphorase via the Q-cycle, but in this case the oxidation is incomplete (about 30% K3H2 is oxidized by the terminal part of the respiratory chain). At 90 microM K3 50% of quinone is reduced by DT-diaphorase and 50% by the respiratory chain NADH dehydrogenase complex enzymes; about 30% of K3H2 is oxidized via the Q-cycle, about 20%--by the terminal part of the respiratory chain and about 50%--by O2 without cytochrome oxidase. Unlike menadione, duroquinone (6-90 microM) is reduced only by DT-diaphorase and is oxidized in all cases by cytochrome oxidase. It was shown that the increase in the mitochondrial matrix volume in low tonicity media decreases the rate of the DT-diaphorase shunt operation.

[A study of the mechanism of cyanide resistant oxidation of succinate from rat liver mitochondria in the presence of menadione]. / Izuchenie mekhanizma tsianrezistentnogo okisleniia suktsinata mitokhondriiami pecheni krys v prisutstvii menadiona.

Two operation regimes of the electron transport system were found in rat liver mitochondria during the cyanide-resistant succinate oxidation catalyzed by menadione. Under isotonic conditions, the mitochondria were found to contain two electron transport components, one of which was sensitive to mucidin, whereas the other one was inhibited by antimycin A. Both electron transport components were inhibited by thenoyltrifluoroacetone (TTFA). In hypotonic media, the polyenzymatic respiratory complex of mitochondria underwent transformations. In this case the electron transport during the cyanide-resistant succinate oxidation was insensitive to mucidin and antimycin A and was suppressed only by TTFA. Some experimental evidence in favour of pathways of electron transfer under different regimes of mitochondrial function was obtained. It was supposed that in isotonic incubation media the cyanide-resistant respiration is mainly due to menadione reduction in two points of the Q-cycle, i.e., in the region of the "i" center and in the "o" center. Under hypotonic conditions, the main electron flux to menadione occurs only via the Q-cycle "i" center. The observed relatively slow reduction of cytochromes b and ci+c plays an insignificant role in the cyanide-resistant respiration. It was shown that the ability of menadione to stimulate the cyanide-resistant respiration is correlated with a higher polarity of this compound as compared with CoQ2 and endogenous CoQ10 of mitochondria. The role of the polyisoprenoid substituent in CoQ10 as a structural component providing for the specificity of interaction with mitochondrial respiratory chain carriers is discussed.

[The effect of vitamin K deficiency in rats on various enzyme systems participating in energy metabolism]. / Vliianie nedostatochnosti vitamina K u krys na nekotorye fermentnye sistemy, uchastvuiushchie v énergoobespechenii.

In alimentary deficiency of vitamin K in rats, accompanied by an increase in the prothrombin time by 30%, activity of kidney creatine kinase and of blood serum alkaline phosphatase was unaltered, while the activity of alkaline phosphatase in small intestinal mucose was decreased by 20% and that of creatine kinase from skeletal muscles--by 10%. In vitamin K-deprived animals the rate of coupling between respiration and mitochondrial phosphorylation was decreased, which might be due to alteration in the NADH-dehydrogenase complex. Menadion reductase activity and cyanide-resistant respiration of mitochondria were unaltered in presence of menadion. Palmitic acid effectively activated of mitochondrial respiration in vitamin K-deprived animals (contrary to the control rats). This effect appears to occur as a result of structural alterations in mitochondria depending on vitamin K level in the organelles.

[Stimulation by quinones of cyanide-resistant respiration in rat liver and heart mitochondria]. / Stimuliatsiia khinonami tsianidrezistentnogo dykhaniia v mitokhondriiakh pecheni i serdtsa krys.

It was shown that hydrophilic benzo- and naphthoquinones stimulate the cyanide-resistant respiration in liver and muscle mitochondria when succinate or NADH and glutamate or malate are used as oxidation substrates. The substrate-dependent oxygen uptake in the presence of cyanide is initiated by menadione, vicasol, 1.2-naphthoquinone, coenzyme Q0 and duroquinone. Rotenone and antimycin A do not inhibit the cyanide-resistant respiration. Oxidation of glutamate and malate in the course of CN-resistant respiration is inhibited by ortho- and bathophenanthroline and p-chloromercurybenzoate, whereas succinate oxidation by tenoyltrifluoroacetone, carboxin and pentachlorophenol. Superoxide dismutase, Cu2+ and catalase inhibit the CN-resistant respiration in the presence of quinones. Addition of catalase to the experimental cell causes O2 release.

[Energy dissipation in the brown fatty tissue of warm-blooded animals]. / Dissipatsiia énergii v buroi zhirovoi tkani teplokrovnykh.

The uncoupling mechanism of respiration and phosphorylation in brown adipose tissue as well as factors affecting this process are discussed. An assumption has been suggested and substantiated experimentally that the uncoupling of respiration and phosphorylation in liver mitochondria caused by vitamin K alimentary deficit may have mechanism similar to the unique uncoupling mechanism of brown fat mitochondria.

[Effect of polymyxins B and M on oxygen uptake by rat liver mitochondria]. / Deistvie polimiksinov B i M na pogloshchenie kisloroda mitokhondriiami pecheni krys.

Polycationic peptide antibiotics, polymixins B and M, are studied for their effect on oxygen uptake by rat liver mitochondria. They both inhibit the process at state 3 and 3p according to Chance. Low concentrations of polymixin M do not affect oxygen uptake by mitochondria at state 4, but its high concentrations inhibit it. Concentration dependence of polymixin B effect on mitochondria at state 4 is of a bell-like character. Competitive interrelations are found between polymixins M and B in their effect on mitochondria at state 4. Chromatography reveals differences in peptide mobility in a thin layer. It is supposed that polymixin inhibition of oxygen uptake by mitochondria is associated with a disordering effect of the polymixins on the membrane structure during peptide binding to the lipid phase of the membranes. Low concentrations of polymixin B are likely to promote an increase in membrane permeability of mitochondria at state 4.

[Inhibition of respiration of mitochondria by o-phenanthroline in a constant magnetic field]. / Ingibirovanie dykhaniia mitokhondrii o-fenantrolinom v postoiannom magnitnom pole.

Preincubation of mitochondria treated with chelator of non-heme ferrum o-phenanthroline (0,067-0,267) for 20 min at 18 degrees C in the constant magnetic field of 330 mT brings about a decrease of the intensity of their uncoupled respiration with NAD-dependent substrates by 15-20% as compared to similar mitochondria preparations without the magnetic field effect. The latter is not realized during conjugated respiration with NAD-dependent substrates at uncoupled respiration with succinate, and in the absence of o-phenanthroline as well.

[Effect of the polycationic antibiotic polymyxin B on the respiratory activity of rat liver mitochondria]. / Deistvie polikationnogo antibiotika polimiksina v na dykhatel'nuiu aktinvost' mitokhndrii pecheni krys.

the mechanism of the effect of the peptide antibiotic polymixin B on respiration of rat liver mitochondria was studied. It was shown that polymixin B at concentrations of (1,6--2,0) . 10(-3) M inhibits mitochondrial respiration in state 3 and 3u irrespective of the oxidation substrate used and activates oxygen consumption in state 4 at lower concentrations. It is assumed that the antibiotic affects mitochondrial respiration by changing the ionic permeability of the membranes.

[Effect of platinum and palladium compounds on mitochondrial enzymatic systems]. / Vliianie soedinenii platiny i palladiia na fermentnye sistemy mitokhondrii.

Effect of platinum and palladium complexes on respiration and ATPase activity in bovine heart tissue as well as on respiration of submitochondrial particles was studied. The highest inhibitory activity was exhibited by the complexes of platinum and palladium with pi-ligands in internal coorhdinational sphere such as ethylene-C H4, norbornadiene-C7H8 and allyl-C3H5. The electron density at the central atom of the complex was not responsible for the inhibitory affect of platinum and palladium on mitochondria.

[Induction of a menadione-dependent respiratory shunt by a platinum complex]. / Induktsiia menadionsavisimogo dykhatel'nogo shunta kompleksom platiny.

Submitochondrial particles (SMP) from the bovine heart were treated with platinum complex--K [C2H4 PtCl3] (Zeize's salt); there occurred a menadion-dependent shunt, this being expressed in menadion stimulation of oxygen consumption under conditions of electron transport block with rotenon. This effect was observed only with the use in the capacity of a substrate of NAD.N2, but not of succinate. Menadion-dependent respiration induced with Zeize's salt was dicoumarol-sensitive, but was not inhibited by antimycin and cyanide, this differentiating it from menadionreductase shunt in the intact hepatic mitochondria.

[Inhibition of nonenzymatic ATP hydrolysis by its binding with the cationic detergent micelles]. / Tormozhenie neenzimaticheskogo gidroliza ATP pri sviazyvanii s mitsellami kationnogo detergenta

The rate of ATP hydrolysis is shown to decrease sharply by its binding with mycelles formed from cetyltrimethyl ammonium bromide (CTAB) (pH 9.0, 20 degrees C). Under these conditions only trace amounts of hydrolytic products have been found in the reaction mixture after a two-months standing. In the absence of mycelles the ATP hydrolysis is practically completed in 7 days. The energies of ATP, ADP and Pi binding with mycelles and at the interface of the "octane - water" system with previously adsorbed CTAB have been measured. The estimates demonstrate that the binding of one negative charge of phosphate anion or that of nucleotides with CTAB at the interface of the "octane - water" system corresponds to the change in free energy, i.e. -3.5 ccal/mol. The sharp deceleration of ATP hydrolysis cannot be due to the shift in the equilibrium of ATP hydrolysis reaction towards the formation of the pyrophosphate bond under conditions when all reaction components are bound to the surface of the mycelles.

[Inhibitors of the slow stage of proton transfer in the link connecting respiration with mitochondrial phosphorylation]. / Ingibitory medlennoi stadii perenosa protona v zvene soprazheniia dykhaniia i fosforilirovaniia mitokhondrii

Electrophilic agents--derivatives of carbonic acids--are found to inhibit respiration, ATP synthesis and reverse electrone transport in intact mitochondria. The inhibition of respiration and ATPase was observed in intact mitochondria at 3 and 3u states (by Chance). Inhibitors concentrations, which caused 50% inhibition, were approximately the same. Sharp decrease of the effect of electrophilic inhibitors on respiration and ATPase activity in mitochondria and submitochondrial particles with substantially impaired coupling system was observed. The following conclusions are drawn on the basis of the data obtained: 1) electrophilic inhibitor attack the coupling site of respiration and ATP synthesis in mitochondria; 2) the reaction of the proton transport from the respiration proton pump to ATP synthetase is one of the slowest steps of the process of ATP-synthesis in mitochondria. A scheme of working the coupling system is suggested which includes the step of proton lateral diffusion.

[Model of bifunctional binding of rotenone and piericidin with mitochondrial NADH-dehydrogenase].

Based on authors' and literature data on the effect of inhibitors of mitochondrial NADH-dehydrogenase a scheme concerning bifunctional binding of specific inhibitors--piericidin A and rotenone with the enzyme is suggested. Analysis on the models, made in correspondence with the requirements of this scheme, permitted to propose conformations in which rotenoides interact with the enzyme.