Microelements preparations obtained during processing of natural flint affect the physiology and biochemistry of bifidobacteria]

Microelement preparations obtained in the course of processing of flint powder stimulate the biological activity of Bifidobacterium adolescentis 94 BIM, grown on complex and synthetic nutritive media. The composition of the microelement preparations differed in the content of cations and anions. Introduction of the preparations into the cultures of physiologically active or anabiotic forms of bifidobacteria changed the parameters of exponential growth: compared to controls, the cultures were characterized by increased specific growth rate and decreased generation time. In the presence of microelements, the development of populations of bifidobacteria was associated with more pronounced accumulation of metabolic products (acetate, lactate, and ethanol). Introduction of microelement preparations increased the rate of synthesis of the extracellular proteinase (maximum content of the enzyme was observed after 3 h, whereas control cultures attained this level only after 6 h).     

The effect of ATP on the malate regulation of oxidative phosphorylation in brain mitochondria

Malate was studied for its effect on the oxidative phosphorylation rate in the rat brain mitochondria in the presence and absence of ATP, succinate being used as a substrate of the respiration. It has been found that malate in the 0.05-0.4 mM concentration range increases the oxidation phosphorylation rate. ATP inhibiting oxidative phosphorylation intensifies the malate stimulation. The malate 0.8 mM concentration removes the inhibiting action of ATP. The regulatory effects of malate and ATP are supposed to be realized at the adenine nucleotide translocator step.     

Preparation of subtilisin BPN' and dextran conjugates

The conditions for subtilishine BPN' binding with bromocyanogen activated dextranes have been selected. The dependence of the enzyme activity and stability from pH and temperature levels has been studied. The stability of a modified enzyme during storage in solution is increased as compared with that of the native enzyme due to a decrease in the autolysis rate. On the basis of diffusion coefficients and sedimentation constants of conjugates, absolute values of their molecular weights have been computed.     

Stimulation of dopamine oxidation in liver mitochondria by palmitic acid in the presence of ATP and <Emphasis Type="Italic">tert</Emphasis>-butylhydroperoxide

The effect of palmitic acid on the oxidation of dopamine, i.e., on the monoamine oxidase (MA-oxidase) activity, was investigated on deenergized liver mitochondria, upon energization by ATP and also in the presence of an oxidizing agent tert-butylhydroperoxide (TBH). It was found that palmitic acid reduces the value of the apparent K _m for dopamine without alteration of the apparent V _max. This points to stimulation of the mitochondrial MA-oxidase activity by palmitic acid at low concentrations of dopamine. Stimulatory effect of palmitic acid may be related to the ability of amphiphilic compounds to increase the negative charge density on the outer mitochondrial membrane. This leads to an increase in the local concentration of positively charged ions of dopamine in the layer adjacent to the membrane near the active site of monoamine oxidase. ATP eliminates the ability of palmitic acid to stimulate the MA-oxidase activity of mitochondria. This effect of ATP is not observed in the presence of the F _O F ₁-ATP-synthase inhibitor oligomycin. Apparently, in the case of vector transport of H⁺ from the matrix induced by ATP-hydrolysis, protonation of palmitic acid anions occurs on the outer mitochondrial membrane, followed by the movement of the neutral molecules to the outer and then to the inner monolayer of the inner membrane. It was found that TBH at a concentration of 300 μM has no significant effect on the ATPase activity of mitochondria and in the presence of ATP and palmitic acid reduces the value of the apparent K _m for dopamine without alteration of the apparent V _max. Antioxidant thiourea eliminates this effect of TBH. We propose that the TBH-induced oxidative stress in the case of ATP-energized mitochondria results in the movement of palmitic acid molecules from the inner to the outer membrane. This leads to an increase in the density of negative charges on the surface of this membrane and, therefore, to the stimulation of the dopamine oxidation.     

Thermodynamic parameters of free oxidation pathways in liver mitochondria

Two pathways of free oxidation in liver mitochondria were examined. One of these pathways is determined by the protonophoric action of free fatty acids, and the other pathway, by passive proton leakage in the absence of fatty acids. According to the model of the proton futile cycle of mitochondria, the protonophoric activity of fatty acids was defined as a quotient of the division of the acceleration of respiration by fatty acid by the coefficient of respiration control for the proton leakage. The temperature dependence of the palmitate protonophoric activity on the Arrhenius plot has a break at 22 degrees C and is characterized by the transition of activation energy from 120 to 60 kJ/mol. The dependence of the respiration rate in state 4 on the Arrhenius plot is linear and, the activation energy is 17 kJ/mol. It was concluded that the first pathway of free oxidation is determined by the cyclic transport of fatty acids with the participation of metabolic carriers, and this process depends on the membrane fluidity; the second pathway is determined by passive leakage of protons through membrane channels, without fatty acids and this process is independent on membrane fluidity.     

Role of the ADP/ATP-antiporter in fatty acid-induced uncoupling of Ca2+-loaded rat liver mitochondria

We show that Ca2+ loading of mitochondria substantially augments the myristate-induced decrease in the transmembrane electric potential difference (deltapsi). Such a Ca2+ action is without effect on the respiration rate and is not accompanied by the high-amplitude swelling when low concentrations of Ca2+ and myristate are used. The myristate-induced deltapsi decrease is prevented and reversed by cyclosporin A (CsA); the decrease is prevented and transiently reversed by nigericin. To explain these effects, we suggest that myristate induces opening of the mitochondrial permeability transition pore at a low-conductance state. Addition of carboxyatractylate (CAtr) after myristate induces the CsA-sensitive uncoupling, but when added after myristate and CsA, CAtr produces a decrease in deltapsi, if the interval between myristate and CsA addition is sufficiently long. The CAtr effect is completely reversed by EGTA and transiently reversed by nigericin. This suggests that the ADP/ATP-antiporter participates in the CsA-sensitive uncoupling when present as a pore complex constituent. ADP/ATP-antiporter that does not take part in the pore complex formation is involved in the CsA-insensitive uncoupling.     

Cyclosporin a inhibits the protonophoric uncoupling activity of laurate in liver mitochondria

The effects of cyclosporin A, carboxyatractylate, and glutamate on the protonophoric uncoupling activity of laurate in liver mitochondria have been studied. It was found that 5 μM cyclosporin A partly inhibits laurate-stimulated mitochondrial respiration, which is suggestive of its recoupling effect, i.e., the ability to suppress the protonophoric activity of this fatty acid. Under these conditions, cyclosporin A has no effect on the ability of carboxyatractylate and glutamate to inhibit the uncoupling effect of laurate. In their turn, these compounds do not influence the recoupling activity of cyclosporin A. The recoupling effects of cyclosporin A, carboxyatractylate, and glutamate are additive: acting simultaneously, they fully suppress the uncoupling activity of laurate. It is concluded that the protonophoric uncoupling activity of fatty acids in liver mitochondria is mediated not only by ADP/ATP and aspartate/glutamate antiporters, but also by a system that is sensitive to cyclosporin A, but is not related with cyclophilin D.     

Biological activity of probiotic microorganisms

Adaptation of bifidobacteria and lactic acid bacteria to nutrient media with increased concentrations of bile (1%) and protein substrates of animal origin allowed the variants resistant to bile and displaying a high production of proteolytic enzymes (active within the pH range of 2.5–9.0) to be selected. Administration of the preparations involving the selected bifidobacteria and lactic acid bacteria assisted in the normalization of the intestinal microflora and activation of protein metabolism in the organism of animals. Specifically, it increased the total protein level in blood serum and redistributed protein fractions, increasing the content of globulins and decreasing albumin concentration.