[Palmitoyl-CoA-dehydrogenase from rabbit adrenals, liver and myocardium]. / Pal'mitoil-KoA-degidrogenaza nadpochechnikov, pecheni i serdtsa krolika.

Partially purified preparations of palmitoyl-CoA dehydrogenase from rabbit adrenal glands, liver and heart tissues exhibited similar kinetic parameters. Km value constituted 6.58, 5.26 and 6.67 microM for the enzyme from adrenal glands, liver and heart tissues, respectively. At the same time, palmitoyl-CoA dehydrogenase possessed lower catalytic capacity in adrenal glands due to the decreased amount of the enzyme as compared with that of liver or heart tissues.

[Kinetic model of the functioning of pyruvate kinase from bovine adrenal cortex]. / Kineticheskaia model' funktsionirovaniia piruvatkinazy iz kory nadpochechnika byka.

The dependence of pyruvate kinase reaction rate on the concentration of one of the ligands--ADP or MgCl2--at constant concentrations of the other ligand was studied. The enzyme activity vs ligand concentration curves have fairly symmetrical peaks which correspond to the range of approximately equal ligand concentrations. The S-shaped dependence is observed only over the range of concentrations close to the dissociation constant for the Mg-ADP- complex (0.7 mM) under the given experimental conditions. The data obtained are consistent with the results of the first model kinetics within the framework of the London-Steck theory. The substrate for pyruvate kinase is the Mg-ADP- complex, while free Mg2+ and ADP3- competitively inhibit the enzyme. The inhibition constants are equal to 44 and 1 mM, respectively. The inhibiting effects of the metal and dinucleotide may be due to the competition with the substrate for the enzyme active site. Taking into consideration the fact that the binding of one of the ligands to the enzyme depends on the presence of the other ligand, a conclusion is drawn that Mg2+ forms a bridge with ADP3- and pyruvate kinase from adrenal cortex.

[Oxidation of [1-14C]palmitoyl-CoA, [1-14C]acetyl-CoA and [2-14C]pyruvate in rabbit adrenal, liver and heart mitochondria under normal conditions and in acute stress]. / Okislenie [1-14C]pal'mitoil-CoA, [1-14C]atsetil-CoA i [2-14C]piruvata v mitokhondriiakh nadpochechnikov, pecheni i serdtsa krolikov v norme i pri ostrom stresse.

The acute immobilized stress was studied for its effect on oxidation rate of [1-14C]palmitoyl-CoA, [1-14C]acetyl-CoA and [2-14C]pyruvate in mitochondria of the adrenals, liver and heart of rabbits. The stress effect on the energy metabolism of adrenals is associated with an increase of the rate of CO2 formation from pyruvate and with a decrease of the rate of CO2 formation from palmitoyl-CoA. Intensified oxidation of all substrates is observed in the heart mitochondria. The processes of beta-oxidation are more active in the liver. The data obtained evidence for differences in the mechanisms of energy metabolism reconstruction under acute stress in tissues with different functional specialization.

[Interaction of succinate dehydrogenase with succinate and oxaloacetate during enzyme activation-deactivation]. / Vzaimodeistvie suktsinatdegidrogenazy s suktsinatom i oksaloatsetatomv protsesse aktivatsii-deaktivatsii fermenta.

The interaction of succinate dehydrogenase from the bovine adrenal cortex with succinate and oxaloacetate was studied in the process of its activation-deactivation. It is supposed that an intermediate unstable complex of succinate dehydrogenase with oxaloacetate plays an important role in the changed enzymic activity.

[Effect of acute stress on the fatty acid composition of lipids of adrenal and heart mitochondria in rabbits]. / Vliianie ostrogo stressa na zhirno-kislotnyi sostav lipidov mitokhondrii nadpochechnikov i serdtsa krolika.

A comparative study of changes in the fatty acid composition of rabbit heart and adrenal mitochondria was carried out after acute (1h) immobilization stress. In heart mitochondria the stress induced a decrease in the content of capric, lauric, myristic and pentadecanic acids. A statistically significant reduction of the amount of heptadecanoic, linoleic, arachidonic acids and an increase in the level of palmitic acid was noted in adrenal mitochondria. The acute stress resulted in differently directed shifts in the saturation of fatty acids. An elevation of the sum of unsaturated fatty acids was observed in the heart, and a decrease was detected in the adrenal glands. The above shifts in the fatty acid composition of adrenal and heart mitochondria provide evidence for different directions of lipid metabolism in these organs following stress.

[Pyruvate kinase in the bovine adrenal cortex]. / Piruvatkinaza kory nadpochechnikov byka.

Pyruvate kinase from bovine adrenal cortex was purified to an electrophoretically homogeneous state. The molecular weight of the native enzyme is about 230 000, that of one subunit is 57 000. The maximal values of the pyruvate kinase initial reaction rate were obtained in 50 mM imidazole-acetate buffer within the pH range of 6.8 to 7.0. The curve of the initial pyruvate kinase reaction rate versus phosphoenolpyruvate (PEP) and ADP concentrations is hyperbolic and obeys the Michaelis-Menten kinetics with Km for PEP and ADP of 0.055 X 10(-3) M and 0.25 X 10(-3) M, respectively. The enzyme is activated by Mn2+ and Co2+ by 43 and 38%, respectively. IDP, GDP, and UDP may be used as analogs of ADP. The enzyme is not activated by fructose-1.6-diphosphate and is inhibited by L-phenylalanine and ATP.

[Isolation, purification and study of the properties of pyruvate kinase from the bovine adrenal cortex]. / Vydelenie, ochistka i izuchenie svoistv piruvatkinazy iz kory nadpochechnikov byka.

Pyruvate kinase (ATP: pyruvate 2-0-phosphotransferase, EC 2. 7. 1. 40) from bovine adrenal cortex was purified 243 fold. The whole purification procedure included ammonium sulphate fractionation, heat treatment, Sephadex HW-55 chromatography and phosphocellulose chromatography. The specific activity of the preparation is 15.6 U/mg at 30 degrees C, the yield--36%. Pyruvate kinase showed only one protein band as judged by sodium dodecyl sulphate acrylamide gel electrophoresis. The enzyme displayed a hyperbolic saturation curve with respect to P-enolpyruvate. The apparent Km for this substrate was 0.55 X 10(-4) M, pH optimum--6.8-7.0. K+ concentrations above 0.1 M inhibit the enzyme.

[Kinetics of the inhibition of succinate dehydrogenase in bull adrenal cortex by malonate and oxaloacetate]. / Kinetika ingibirovaniia suktsinatdegidrogenazy kory nadpochechnikov byka malonatom i oksaloatsetatom.

The activity of succinate dehydrogenase from bull adrenal cortex was studied as affected by malonate and oxaloacetate. The both substrate analogs without preincubation (separately and in the mixture) inhibit the enzyme by the competitive type. After a 3 min oxaloacetate preincubation of the enzyme inhibition is of a mixed character. Malonate under these conditions lowers the oxaloacetate effect without changing the type of inhibition. It is supposed that the protective effect is due to a high rate of formation and decay of the enzyme-inhibitory malonate complex.

[Corticosteroid mechanism as a leading element of the thymotropic effect of oxythiamine in the rat]. / Kortikosteroidnyi mekhanizm--vedushchee zveno timotropnogo éffekta oksitiamina u krys.

Oxythiamine B1-hypovitaminosis in adrenalectomized male rats is not accompanied by acute thymus involution. This is not so much related to hypocorticoidism per se, as to a decrease in metabolic potencies of the antivitamin, particularly to a negligible depression of thymocyte tolerance to hydrocortisone. Sex differences in morphological parameters of thymus lymphopoiesis have been found after adrenalectomy.

[Oxidation of different substrates in mitochondria of bovine and rat adrenal cortex]. / Okislenie razlichnykh substratov v mitokhondriiakh kory nadpochechnikov byka i krys.

The rate of oxygen uptake by mitochondria of bovine and rat adrenals was determined during oxidation of the Krebs cycle substrates. Succinate is established to be oxidized most actively under in vitro conditions.

[Carbohydrate metabolic index change in the liver on the administration of thiamine or oxythiamine to rats with a varying hormonal level]. / Izmenenie pokazatelei uglevodnogo obmena v pecheni pri vvedenii tiamina ili oksitiamina krysam s razlichnym gormonal'nym fonom.

The effects of thiamine and oxythiamine on glucoso-6-phosphate, fructoso-6-phosphate, ATP, aldopentoses, glucose and glycogen levels were studied in the liver of rats with different hormonal levels. Thiamine and insulin were shown to produce a similar effect on the liver levels of hexosomonophosphates, aldopentoses and glucose. Oxythiamine effects as compared to those elicited by thiamine and insulin are always contrasting. It is suggested that the insulin-like action of thiamine is consequent on the primary effect the vitamin exerts on the functional activity of the insular apparatus of the pancreas.

[Protein biosynthesis in the rat liver in natural fluctuations of the steroid background]. / Biosintez belka v pecheni krys pri estestvennykh kolebaniiakh steroidnogo fona.

The results of the study of protein and RNA biosynthesis and inducation of glucose-6-phosphatase activity in the rat liver at natural (seasonal) fluctuations of the steroid background are presented. It is shown that the adrenal gland seasonal activation increases incorporation of precursors labeled (l14C-leucine and l14C-orotic acid) into total liver proteins and RNA and enhances glucose-6-phosphatase activity in the rat liver. The conclusion is drawn that the changes in the endogenous corticosteroid level have regulative significance for protein biosynthesis in the rat liver.

[Mechanisms of liver transketolase activation in B1-deficient rats after administration of thiamine]. / O mekhanizmakh aktivatsii transketolazy pecheni B1-gipovitaminoznykh krys vvedeniem tiamina.

Gel filtration and equilibrium dialysis demonstrated that the hyaloplasmic fraction of the liver of B1-deficient rats does not practically bind C-TDP in vitro. An addition of the excess of non-labelled coenzyme does not increase the transketolase activity. The data obtained suggest that transketolase activation in the hyaloplasmic fraction of the liver of B1-deficient rats after administration of thiamine in vivo is due to stimulation of the additional synthesis of the enzyme protein rather than to the saturation of the free apoenzyme with newly-formed TDP. In vivo and in vitro studies suggest that the hyaloplasmic fraction of the liver of B1-deficient rats contains no free apoenzyme of transketolase.

[Adrenal cortex and vitamin PP. The effect of corticosteroids on the NAD level in the rat liver after the administration of excess nicotinic acid or nicotinamide]. / Kora nadpochechnikov i vitamin PP. Vliianie kortikosteroidov na uroven' NAD v pecheni krys posle vvedeniia izbytka nikotinovoi kisloty ili nikotinamida.

The NAD content in the liver was experimentally studied in intact, adrenalectomized rats and those given hydrocortisone following nicotinic acid and nicotinamide administration. The NAD concentration in the liver rose linearly and equally during the first 4 experimental hours after the nicotinamide administration (200 mg/kg). A conclusion was drawn that in administration of exogenous precursors the coenzyme biosynthesis did not depend on the initial hormonal background.

[Further comment on the lipotropic action of niacin]. / Eshche raz o lipotropnom deistvii niatsina.

An investigation into the total lipids, fatty acids, total phospholipids and ATP content in the liver of rats given nicotinamide, separately and together with hydrocortisone, showed that the disclosed shifts mutually correlate well and may be explained in keeping within the bounds of the idea as to the lipotropic action of the preparations. The coincidence of the corticosteroids and nicotinamide effects in regards to mobilization of lipids and their oxidation in the liver presumes a hormonal causation of shifts on the level of lipids metabolism.

[On corticosteroid control of NAD splitting in rat liver]. / O kortikosteroidnom kontrole rasshchepleniia NAD v pecheni krys.

Hydrocortisone increases the NAD-glycohydrolase activity in the liver of intact rats. Actinomycin D does not influence the stimulating effect of hydrocartisone with respect to the NADase activity of the liver. The degree of activation of NAD enzymic splitting with administration of 200 mg/kg of nicotinamide depends on the initial hormonal background: with hypercorticoidism it is higher and with hypocorticoidism it is lower than the level found in the intact animals which were given the same dose of the vitamin. An inverse correlation between the steroid-dependent shifts of the NADase activity and the content of NAD in the liver may evidence for their interdependence. A conclusion is drawan on the paramount importance of corticosteroid control of the nucleotide splitting in vivo for formation of NAD cellular pool.

[Thiamine- and thiamine diphosphate-binding capacity of the hyaloplasmic fraction of rat liver]. / Izuchenie tiamin- i tiamindifosfatsviazyvaiushchei sposobnosti gialoplazmaticheskoi fraktsii pecheni krys.

Hyaloplasmic fraction of rat liver tissue did not bind 14C-thiamin and 14C-thiamin diphosphate in vitro as shown by means of gel filtration and equilibrium dialysis. All the thiamin and 2/3 of thiamin diphosphate were in vivo in free state or in a state unbound with proteins. Hyaloplasm lost readily the endogenous thiamin diphosphate during dialysis. Endogenous thiamin diphosphate (about 1/3 of the initial content), resistent to dialysis and gel filtration, was apparently included in transketolase in hyaloplasmic fraction of rat liver tissue.

[Mechanisms of the antilipemic action of niacin]. / O mekhanizmakh antilipemicheskogo deistviia niatsina.

In tests conducted with albino rats the influence of nicotinic acid, nicotinamide, hydrocortisone and their combinations on a number of factor characterizing directly or indirectly the state of the lipid metabolism in the liver was investigated. It is suggested that hormonal mediation (preliminary stimulation of the suprarenals) may play a significant part in the realization of hypolipemic activity of niacin, its concrete mechanism being oxidation of the lipids, controlled by corticosteroids.

[Hormonal and vitamin regulation of glucose-6-phosphatases activity in the liver]. / K voprosu o gormonal'noi i vitaminnoi reguliatsii gliukozo-6-fosfataznoi aktivnosti v pecheni

Glucose-6-phosphatase (G-6-Phase) activity in the rat liver is established to correlate directly with the content of corticosteroids in blood: it lowers with hypocorticoidism (adrenalectomy) and rises with hypercorticoidism (stress). The highest G-6-Phase activity in the liver of the intact animals is observed in autumn, the lowest one in spring, i.e. in the periods when the adrenals function has minimal and maximal values, respectively. Thiamin (0.4 g/kg) is shown to cause a decrease in the G-6-Phase activity in the liver of the intact rats and adrenalectomized or hypophysectomized animals. An assumption is advanced that the found in the experiment a pronounced insulin-like effect of vitamin B with respect to the G-6-Phase activity is connected with an intensified synthesis of the corresponding hormone in the pancreas.