[Development of diagnostic test system based on fluorescent polarization immunoassay method for detection of antibodies to HCV nucleocapsid protein].

The antigen activity of the synthetic fluorescently labeled peptides, overlapping immunoresponsive epitops a.a. 7-19, 20-34 from N-end part and a.a. 73-85 from the central area of the nucleocapsid protein of C hepatitis virus, was tested using the method of fluorescent polarization immunoassay (FPIA) with 40 samples of the blood serum of patients with viral C hepatitis. A comparative study of analytic characteristics of FPIA method was performed, based on the application of synthesized peptides, as well as of the commercial ELISA test system (BEST anti-HCV-test 4, Vector Best Ltd.). The performed research revealed that the developed method has a high specificity and sensitivity level. The comparability of summary FPIA results with the commercial ELISA test system was 85%, which evidences the prospects of further research in this direction. The principal possibility of the application of the polarization fluorescent immunoassay for the determination of antibodies to the nucleocapsid protein of the C hepatitis virus in clinical serum samples was demonstrated.

Regulation of NAD(+)-dependent isocitrate dehydrogenase in the citrate producing yeast Yarrowia lipolytica.

The mechanism of the increased accumulation (overproduction) of citric acids in the yeast Yarrowia lipolytica while growing in the presence of glucose under nitrogen deficiency was investigated. The limitation of the yeast growth by the source of nitrogen decreases the total content of nucleotides and increases the ratios of ATP/AMP and NADH/NAD+. NAD+-Dependent isocitrate dehydrogenase, an enzyme of the tricarboxylic acid cycle playing a key role in the regulation of biosynthesis of citric and isocitric acids, was isolated from Y. lipolytica. The molecular weights of the native enzyme and its subunits were found to be 412 and 52 kD, respectively. It is concluded that the enzyme is a homo-oligomer consisting of eight subunits. Investigation of the effect of some intermediates of the tricarboxylic acid cycle on the activity of this enzyme suggests that the enhanced excretion of citric acids can be caused by the inhibition of NAD+-dependent isocitrate dehydrogenase due to the decrease in the content of AMP and increase in the NADH/NAD+ ratio in the cells of Y. lipolytica under depletion of nitrogen.

[The level of cytochrome P-450 in Saccharomyces cerevisiae with disruptions of various stages of sterol synthesis]. / Soderzhanie tsitokhroma P-450 v drozhzhakh Saccharomyces cerevisiae s narusheniiami razlichnykh stadii sterinovogo sinteza.

A spectral analysis of cytochromes P-450 in Saccharomyces cerevisiae cells and in mutant strains accumulating the ergosterol biosynthesis intermediates was carried out. Glucose repression and semianaerobiosis were found to induce cytochrome P-450 synthesis. No differences in the cytochrome P-450 content in mutant nys 3, nys 4 and parent strains were observed. Mutants nys 5 accumulated large amounts of cytochrome P-450. Cytochrome P-420 was detected in wild type strains and in mutants nys 3 and nys 4. The cultivation time and aeration conditions were shown to be unimportant for the generation of cytochrome P-420.

Inhibition of succinate oxidation and K+ transport in mitochondria during hibernation.

Respiration of liver mitochondria of ground squirrels changes with physiological state. The inhibition of respiration at the level of dehydrogenases occurs during hibernation which is spontaneously removed during arousal. The main mechanism causing a decrease in respiration during hibernation seems to be the inhibition of succinate oxidation, induced by oxaloacetic acid. This is evidenced by the removal of the inhibition by glutamic and isocitric acids. A close correlation between the changes of K+ transport in mitochondria and of the physiological state of hibernator is observed. During hibernation the K+ transport rate decreases 3 times and during arousal it increases 1.5-fold in comparison with the active animals. The K+ content in mitochondria of hibernating and active ground squirrels is the same, whereas during arousal it increases 2-fold.

[Mechanism of the Crabtree effect: influence of pH on the rate of mitochondrial respiration]. / O mekhanizme éffekta krebtri: vliianie pH sredy inkubatsii na skorost' dykhaniia mitokhondrii.

A detailed study of dependence of mitochondrial respiration on pH of incubation medium has been carried out. It was shown that during oxidation of malic, succinic and ascorbic acids mitochondrial respiration shows a sharp fall, when the pH of incubation medium is decreased from 7.5 to 6.5. It was assumed that one of the possible causes of the Crabtree effect is a reduction of the pH value of the cytoplasm.

[Induction of hydrogen ion transport in mitochondrial membranes]. / Induktsiia transporta ionov vodoroda v membranakh mitokhondrii.

The system of ion transport in mitochondria induced with Brensted acids (H+-acids) was studied. It has been shown that an increase of the activity of hydrogen ions in the incubation medium (pH decrease) along with the earlier obtained [3--5] K+/H+ exchange brings about the appearance of the system of electrogenic transport of potassium ions in mitochondria. A synchronous functioning of the two systems indicated provides the electrogenic transmembrane transport of hydrogen ions through the mitochondrial membrane (Fig. 3, diagram 6). When studying the induction of ionic transport the data were obtained in favour of the concept that the induction resulted from conjugated oxidation and hydrolysis of lipids.

[Nucleotide control of ionic transport and ATP synthesis in mitochondria]. / Reguliatsiia nukleotidami protsessov ionnogo transporta i reaktsii sinteza ATP v mitokhondriiakh.

It was demonstrated that under certain experimental conditions the P/O ratio of oleate-treated mitochondria in hypotonic media at low pH values is sharply decreased irrespective of high ADP/O values. This is probably due to a drastic fall in the ionic permeability of membranes induced by ADP. The effect observed is due to ADP (ATP) interaction with nucleotide translocase, since atractyloside eliminates the effect of ADP on the ionic permeability. It was demonstrated that nucleotide translocase is immediately involved in regulation of the functioning of the oxidative phosphorylation system of mitochondria.

[Ion currents in mitochondrial and liposome membranes induced by acid action]. / Ionnye potoki v membranakh mitokhoncrii i liposom, indutsirovannye deistviem kislot.

It is shown that potassium ion yield from mitochondria observed under low pH of the incubation medium and at the addition of n-(N,N-di-2-Chloridethyl)aminophenylacidic acid and low concentrations of 2,4-dinitrophenol results from the formation of non-electrogenic (nigericyn-like) carrier. The data are obtained which show that under experimental conditions a weak electrogenic transport of ions is observed along with non-electrogenic ion transport in the membranes.

[Induction of ion transport coupled to oxidative reactions in the membranes of mitochondria and liposomes]. / Induktsiia ionnogo transporta, sopriazhennaia s okislitel'nymi reaktsiiami v membranakh mitokhondrii i liposom.

The mechanism of induction of potassium permeability for mitochondrial membranes under special conditions was under study. Conditions were such as: 1--incubation of mitochondria in medium with low meaning of pH (6,0--6,5), 2--incubation in preseace of electrophylic agent--p-(N,N-di-2-chloroethyl) aminophenylacetic acid, which is hydrolized to HCl and 3-lipidsoluble acid, 2,4-dinitrophenol. It is shown that the named mechanism in any case requires the oxidation of lipids of mitochondrial membranes.

[High resolution NMR study of mitochondria and submitochondrial fragments]. / Issledovanie mitokhondrii i submitokhondrial'nykh fragmentov metodom IaMR vysokogo razresheniia

The PMR spectra of mitochondrias, inner and outer mitochondrial membranes and also, matrix and intermembrane material are presented. The essential effect of sonication on the structure of inner membranes of mitochondrias is demonstrated.