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S V Popova

Publications and source records attributed to S V Popova.

28 records · Page 2Linked to original sources
PubMedDate not supplied

[Effect of ethanol and clofibrate on the activity of lipid catabolism enzyme systems in rat liver].

Male rats were fed ethanol as a constituent of an isocaloric diet. Ethanol administration caused hypercholesterolemia and accumulation of lipids in the liver. However, it did not alter enzymatic activity of fatty acids and cholesterol catabolism in the organ. Addition of the hypolipemic agent clofibrate to the ethanol-containing diet reduced the adverse effects of ethanol on lipid metabolism due to activation of peroxisomal and mitochondrial enzymes involved in oxidative degradation of lipids in the liver cell.

Alcohol Oxidoreductases↗
PubMedDate not supplied

[Effect of chronic administration of ethanol on the enzyme activity of rat serum, liver and brain].

Effect of chronic ethanol administration on some enzyme activities was studied in plasma membranes, brain homogenate cytoplasmic reticulum and cytosol, liver homogenate and microsomal fractions and blood serum. Ethanol was ingested as a constituent of isocaloric "semiliquid" diet. The investigation was carried out to estimate the diagnostic value of certain enzymes in evaluation of alcohol intoxication. In male rats ethanol caused remarkable hyperlipidemia, accumulation of lipids in liver tissue and elevation of gamma-glutamyl transpeptidase activity in blood serum and brain tissue. In liver tissue moderate induction of glucose-6-phosphatase, NADPH-cytochrome c reductase and alkaline phosphatase was observed. The putative mechanism of elevation of organospecific enzyme activities in blood serum during chronic ethanol consumption is discussed.

Alcoholism↗
PubMedDate not supplied

[Multiplicity of auto-oscillations and steady states in an open reaction catalyzed by E. coli phosphofructokinase. Quantitative model].

A quantitative mathematical model of two-substrate reaction catalized by phosphofructokinase from E. coli has been investigated. The model takes into account the tetrameric enzyme structure and resulting kinetic peculiarities of the reaction catalized, in particular, iso-and alosteric effects of ADP on enzyme activity. Fitting of the model parameters to experimental data allowed to approximate these data with good accuracy. The ranges of admitted rates of fructose-6-phosphate input and ATP regeneration at which autooscillations and multiple steady-states occur in the system have been calculated. A minimal open system with three enzymes has been proposed for experimental demonstration of the autooscillatory behaviour.

Adenosine Diphosphate↗
PubMedDate not supplied

[Characterization of clofibrate-stimulated alkaline phosphatase in rat liver].

Hypolipidemic agent clofibrate induced the alkaline phosphatase activity in rat liver but did not affect this activity in kidney, brain, heart and intestine. In liver cells the clofibrate induced alkaline phosphatase was localized in plasma membrane and cytosol and was similar to the enzyme found in normal hepatocytes by its main properties (pH optimum, inactivation temperature, substrate specificity, Km, effect of inhibitors and inducers). The putative mechanism of the alkaline phosphatase induction in liver tissue by means of clofibrate is discussed.

Alkaline Phosphatase↗
PubMedDate not supplied

[Kinetic and regulatory properties of reversible enzymic reactions].

The model of a reversible reaction catalyzed by an oligomeric enzyme has been investigated. The regions of parameter values have been estimated at which the model describes "unidirectional" or alternative effects of allosteric modifiers on the rates of forward and backward reactions. The plausible explanation and mathematical description are offered for kinetic and regulatory peculiarities of reversible reactions catalyzed by NAD-dependent isocitrate dehydrogenase and catabolic ornithine carbamoylphosphate transferase. The phenomena of unidirectional catalysis of alternative directions of a reversible reaction by different enzymes are considered.

Enzymes↗
PubMedDate not supplied

[Transformation of enzyme graphs having the form of a multidimensional parallelepiped].

The graph of an enzymic reaction having the form of a multidimensional parallelepiped with equal opposite sides may be substituted, as shown, by consideration of n separate unidimensional subgraphs, which simplifies significantly the procedure of derivation of steady-state relations. The applications of this method to derivation of steady-state rate equation for a two-substrate reaction with random addition mechanism and to generalization of the Monod et al. model for multisubstrate reactions have been considered.

Enzymes↗
PubMedDate not supplied

[Regulatory reversible enzymic reactions. Theoretical analysis].

A mathematical model has been derived and analysed describing the relationship between the rate of an enzymic reaction S1 E(R,T)A in equilibrium S2 and concentrations of substrates S1 and S2 and their analogue A capable of reversible binding to active sites of an olygomeric enzyme E(R, T). The conditions have been presented for the model to describe various types of kinetic curves, sygmoidal, curves with extremuma and intermediate plateau. The regions of parameter values have been estimated within which isosteric product activation can be observed in reactions S1 in equilibrium E(R,T) S2 and S1 E(R,T) in equilibrium S2. Two phenomena registered in experiments with olygomeric enzymes have been interpreted in the model terms, namely, the undirectional influence of isosteric and allosteric effectors on the rates of forward and reverse reactions and occurence of a reversible enzymic reaction in thermodynamically unfavourable direction. The results presented are shown to be valid for multisubstrate reactions catalysed by olygomeric enzyme E(R, T).

Enzymes↗