[Structure-functional properties of conjugates of proteins with polyalkylene oxides: study by a fluorescence method]. / Strukturno-funktsional'nye svoistva kon''iugatov belkov s polialkilenoksidami: issledovanie metodom fluorestsentsii.

A fluorescent study of some structural and functional properties of conjugates of a number of proteins (bovine serum albumin, pyruvate kinase, alpha-chymotrypsin, and the two toxic proteins of plant origin--ricin and viscumin) with polyalkylene oxides (polyethylene glycol and pluronic) has been carried out. Analysis of the intrinsic protein fluorescence showed that the structure and stability of various protein conjugates to denaturing agents change only slightly: the conformational mobility of tryptophan residues accessible to the solvent decreases, whereas that of tryptophan residues localized in the protein regions of low polarity remains unchanged. Besides, the conjugates display a higher thermal stability in comparison with their native proteins. The fluorescence of 1-anilinonaphthalene-8-sulfonic acid and water insoluble 2',3',4',5'-tetrabenzoylriboflavin bound to the native and modified proteins indicated that modification of the proteins with polyalkylene oxides decreased the polarity and increased the viscosity of the microenvironment. Hence, this modification makes it possible to change some functional characteristics of the protein without causing any significant changes in its structure.

[The effect of bovine serum albumin conjugates with polyalkylene oxides on the respiration of heart mitochondria]. / Vliianie kon''iugatov bych'ego syvorotochnogo al'bumina s polialkilenoksidami na dykhanie mitokhondrii serdtsa.

The effect of polyalkylene oxides and pluronics (block copolymers of polyethylene oxide and polypropylene oxide) and their conjugates with bovine serum albumin (BSA) on respiration and oxidative phosphorylation in rat heart mitochondria has been studied. The pluronics and their conjugates with BSA stimulate state 4 respiration in mitochondria, inhibit state 3 respiration and 2,4-dinitrophenol-uncoupled state respiration, decrease the respiratory control, ADP/O ratio values and display weak uncoupling properties. The pluronics inhibit respiration and oxidative phosphorylation more effectively than their conjugates with BSA. The effect of the conjugate on the mitochondrial membrane is reversible, in contrast with that of the pluronics. The compounds under study act preferentially on the NADH-dehydrogenase complex of the respiratory chain. Inhibition of respiration in thymocytes by these compounds confirms their ability to penetrate into the cell membrane. The dependence of membranotropic properties of polyalkylene oxides and their conjugates with the protein on their structure is discussed.

[The effect of alkylresorcinol on the respiration and synthesis of nucleic acids and proteins in isolated thymocytes]. / Vliianie alkilrezortsina na dykhanie, sintez nukleinovykh kislot i belka v izolirovannykh timotsitakh.

The effect of the membranotropic agent alkylresorcinol 5C10 on the respiration, nucleic acid and protein synthesis in isolated thymocytes was studied. Within the 5C10 concentration range of 10(-7)-10(-5) M, the inhibition of respiration and incorporation of labelled precursors into thymocyte proteins and DNA was observed. In case of respiration and protein synthesis, a 50% inhibition was observed at alkylresorcinol concentrations of 10(-8) and 0.5.10(-5) M, respectively. The rate of 3H-thymidine incorporation into DNA progressively decreased already at 5C10 concentration of 10(-7) M. At 10(-6) M alkylresorcinol its inhibiting effect on DNA synthesis was about 30% and it did not change with a further rise in the inhibitor concentration up to 10(-5) M. In contrast, the rate of RNA synthesis significantly increased (ca. by 20%) within the alkylresorcinol concentration range of 10(-6)-10(-5) M. At 5C10 concentrations above 10(-5) M, the state of thymocytes in the preagglutination period appeared to be critical and was characterized by a dramatic inhibition of all the parameters under study. The experimental results suggest that alkylresorcinol 5C10 causes the inhibition of processes that are functionally coupled with biological membranes.

[The effect of anthracyclines on heart mitochondria respiration during the action of creatine phosphokinase]. / Vliianie antratsiklinov na dykhanie mitokhondrii serdtsa v usloviiakh raboty kreatinfosfokinazy.

It was shown that during glutamate+malate oxidation in the presence of creatine, antitumour anthracycline antibiotics strongly inhibit the rate of oxygen uptake by rat heart mitochondria; ADP excess activated the respiration up to the initial level, i.e., that observed after the first addition of ADP. Carboxyatractyloside addition to a system containing creatine (or hexokinase+glucose) results in the stimulation of rubomycin-induced mitochondrial respiration. Substitution of carboxyatractyloside by oligomycin gives very similar results. It is supposed that anthracycline antibiotics exert a manyfold effect on heart mitochondrial membranes which results in impaired compartmentation of enzymatic systems providing for oxidative phosphorylation.

[Inhibition of synthesis of nucleic acids, proteins and respiration in isolated thymocytes by anthracyclines]. / Ingibirovanie antratsiklinami sinteza nukleinovykh kislot, belka i dykhaniia v izolirovannykh timotsitakh.

The effect of anthracycline antibiotics such as carminomycin, daunomycin (rubomycin) and adriamycin on respiration and synthesis of nucleic acids and protein was studied comparatively. The anthracyclines inhibited the processes. By their efficacy in that respect they could be arranged in the following order: carminomycin greater than rubomycin greater than adriamycin. Thus, 50 per cent inhibition of nucleic acid synthesis in the thymocytes required 0.027, 0.044 and 0,173 mM of carminomycin, rubomycin and adriamycin respectively. Protein synthesis and respiration in the thymocytes were less sensitive to the effect of the anthracyclines than synthesis of nucleic acids. The study results were compared with the literature data on the effect of the compounds on respiration and synthesis of nucleic acids and protein in tumour and bacterial cells.

[Relation between respiration and swelling of liver mitochondria induced by anthracycline antibiotics]. / Sootnoshenie dykhaniia i nabukhaniia mitokhondrii pecheni, indutsiruemykh antratsiklinovymi antibiotikami.

The anthracycline antibiotics rubomycin (daunorubicin) and carminomycin at concentrations which stimulate mitochondrial respiration in the absence of ADP induce the swelling of rat liver mitochondria. Under these conditions, the lipid peroxidation (LPO) inhibitor ionol slows down both the respiration and swelling of mitochondria. This suggests that stimulation of respiration and swelling under effects of the antibiotics largely depend on LPO. In the presence of the respiration inhibitor antimycin no effect of ionol is observed. Adriamycin (doxorubicin) stimulates mitochondrial respiration in a lesser degree than rubomycin and carminomycin and fails to induce mitochondrial swelling.

[Effect of rubomycin, carminomycin and adriamycin on respiration in liver mitochondria in various metabolic states, respiratory control and ADP/O ratio]. / Deistvie rubomitsina, karminomitsina i adriamitsina na dykhanie mitokhondrii pecheni v razlichnykh metabolicheskikh sostoianiiakh, dykhatel'nyi kontrol' i otnoshenie ADP/O.

A comparative study on the effects of antitumour antibiotics of the anthracycline group (rubomycin, carminomycin and adriamycin) on respiration and oxidative phosphorylation in liver mitochondria in various metabolic states has been carried out for the first time. It was shown that the antibiotics under study cause partial inhibition of mitochondrial state 3 respiration, which is eliminated by an uncoupler. Treatment of liver mitochondria with the antibiotics decreases the ADP/O and respiratory control values and stimulates state 4 respiration. The latter is partly inhibited by oligomycin. The uncoupled respiration is decelerated in the presence of the antibiotics. Under these conditions the oxidation of succinate is inhibited by lower concentrations of the antibiotics than that of NAD+-dependent substrates. It was shown that the maximal activity is exerted by the most polar agent carminomycin, while the hydrophobic rubomycin is the least active. The experimental results are discussed in terms of the toxic effect of antitumour antibiotics.

[Transmembrane redox reactions, coupled with proton transfer in lipid bilayer membranes]. / Issledovanie transmembrannykh okislitel'no-vosstanovitel'nykh reaktsii, sviazannykh s perenosom protona na bisloinykh lipidnykh membranakh.

The transmembrane reaction of ferricyanide reduction by exogenous ascorbate in the liposomes in the presence of N,N,N',N'-tetramethylparaphenylenediamine (TMPD) or 2,3,5,6-tetramethylphenylenediamine (DAD) was investigated. The reaction equilibrium was shown to depend on the intraliposomal pH. At alkaline pH values under the experimental conditions used TMPD functions mainly as an electron carrier, while at acidic pH values TMPD effectuates a coupled transmembrane electron and proton transfer. This reaction is paralleled with local changes in the pH values in the unstirred layer near the membrane.

[Proton translocation coefficient for H+-ATPase of rat liver mitochondria]. / Koéffitsient translokatsii protonov H+-ATPazy mitokhondrii pecheni krys.

Some features of H+-ATPase function in intact mitochondria of rat liver were studied. Simultaneously the activities of ATPase and proton translocase were measured, using a previously described technique. The proton translocation coefficient of H+-ATPase has been found to be equal to 3.6. The protonophore 3.5-di-tert-butyl-4-hydroxybenzylidenemalononitrile diminishes the proton translocation coefficient. It was concluded that when considering the mechanism of proton translocation by H+-ATPase, it is necessary to assume the possibility of transport of 3 or 4 protons per every hydrolyzed molecule of ATP allowing a changeable efficiency of the process. The decrease of the translocase coefficient in the presence of the protonophore appears to result from the ability of this uncoupler to return the transferred protons to the mitochondrial matrix.

[Lability of coupling between proton translocase and ATPase of mitochondrial H+-ATPase complex]. / Labil'nost' sopriazheniia mezhdu translokazoi protonov i ATPazoi H+-ATPaznogo kompleksa mitokhondrii.

The interrelationship between the ATPase and H+-translocase functions of mitochondrial H+-ATPase was studied. The efficiency of the functioning was estimated by the value of coupling coefficient (Kc), which is represented by a ratio of proton translocation rate versus ATP coupling hydrolysis rate. It was shown that under conditions of increased concentrations of ATP and low concentrations of oligomycin the value of Kc is decreased. The increase in the concentration of valinomycin results in an increase of Kc. It was also found that the H+-ATPase activity shows a considerable increase during incubation of mitochondria, reaching its maximum with respect to both functions 1--2 min after addition of ATP. The data obtained are indicative of a lack of tight coupling between the H+-translocase and ATPase functions of mitochondrial H+-ATPase. The mechanism of action of H+-ATPase is discussed.

[Several features of the oligomycin effect on phosphorylating oxidation of mitochondria at various states]. / Osobennosti deistviia oligomitsina na fosforilirufushchee okislenie mitokhondrii v razlichnykh sostoianiiakh

Effect of oligomycin on the oxygen uptake at the 4th state of the respiration chain in mitochondria with the stable coupling of respiration and phosphorylation is studied. Oligomycin is shown to inhibit the respiration in the absence of exogenous phosphorylation substrate. The inhibition curve at the 4th state is hyperbolic, at the 3d state-it is S-form. The antibiotic inhibited the oxidation of beta-hydroxybutric acid at the 4th state more intensively, than succinate oxidation. It is suggested that ATP-synthetase acts for the expense of endogenous ADP at the 4th state of the respiration chain.