[A kinetic model of beta-galactosidase of Escherichia coli].

On the basis of previously published experimental data, the catalytic cycle of Escherichia coli galactosidase has been reconstructed. The enzyme plays a key role in the transcription regulation of lac operon. Using the proposed scheme, we have built a kinetic model that takes into account the reactions of hydrolysis, isomerization as well as galactosylation. Using the experimental data and optimization algorithms, all parameters of the model have been estimated. On the basis of the model, the features of beta-galactosidase functioning have been predicted in a wide range of conditions.

[Purification and characterization of milk-clotting enzymes from oyster mushroom (Pleurotus ostreatus (Fr.) Kumm.)].

Three enzymes with milk-clotting activity have been isolated from the fruiting bodies of Pleurotus ostreatus (Fr.) Kumm.) by (NH4)2SO4 precipitation, gel chromatography on Sephadex G75, and ion exchange chromatography on carboxymethylcellulose (CMC). Isoelectric points of the enzymes, as determined by isoelectrofocusing, equaled 4.2, 6.7, and 8.8. Inhibition analysis showed that the enzymes with isoelectric points of 4.2 and 6.7 belong to the class of metal-dependent proteinases, while the enzyme with the isoelectric point of 8.8 belongs to the serine protease class.

[A kinetic model of functioning and regulation of Escherichia coli isocitrate dehydrogenase].

A Rapid Equilibrium Random Bi Ter mechanism of formation of two dead-end complexes was proposed to describe the experimental data on the functioning of E. coli isocitrate dehydrogenase (IDH). A kinetic model for the enzyme functioning was constructed, which assumes that it is regulated through reversible phosphorylation by its kinase/phosphatase, which in turn is regulated by IDH substrates and central metabolites such as pyruvate (Pyr), 3-phosphoglycerate (3-PG), and AMP. It was shown using the model that increasing the concentration of these effectors results in an increase of the active part of IDH, thus leading to an increase in the Krebs cycle flux. We predict that the ratio of the phosphorylated and free forms of IDH (IDHP/IDH) is more sensitive to AMP, NADPH, and isocitrate concentrations than to Pyr and 3-PG. The model allows a realistic prediction of changes in the IDHP/IDH ratio, which would occur under changes of biosynthetic and energetic loading of the E. coli cell.

[A kinetic model of the cytochrome bf complex. Evaluation of kinetic parameters]. / Kineticheskaia model' tsitokhromnogo bf-kompleksa. Otsenka kineticheskikh parametrov.

A kinetic model of the cytochrome bf complex was developed on the assumption that the Q-cycle operates. The bf complex was considered as a membrane enzyme catalyzing the electron transfer from plastoquinol to plastocyanine, which is coupled with proton translocation from the chloroplast stroma to the thylakoid lumen. The dependence of the electron transfer rates on the value of the transmembrane electric potential was taken into account. The model was applied to describe the experimental data on the flash-induced turnover of cytochromes b, plastocyanine, and the kinetics of proton deposition in the thylakoid lumen. The estimation of model parameters was performed.

Kinetic model of imidazologlycerol-phosphate synthetase from Escherichia coli.

Based on the available experimental data, we developed a kinetic model of the catalytic cycle of imidazologlycerol-phosphate synthetase from Escherichia coli accounting for the synthetase and glutaminase activities of the enzyme. The rate equations describing synthetase and glutaminase activities of imidazologlycerol-phosphate synthetase were derived from this catalytic cycle. Using the literature data, we evaluated all kinetic parameters of the rate equations characterizing individually synthetase and glutaminase activities as well as the contribution of each activity depending on concentration of the substrates, products, and effectors. As shown, in the presence of 5 -phosphoribosylformimino-5-aminoimidazolo-4-carboxamideribonucleotide (ProFAR) and imidazologlycerol phosphate (IGP) glutaminase activity dominates over synthetase activity at sufficiently low concentrations of 5 -phosphoribulosylformimino-5-aminoimidazolo-4-carboxamideribonucleotide (PRFAR). Increased PRFAR concentrations resulted in decreased contribution of glutaminase activity and, consequently, increased the contribution of synthetase activity in the enzyme functioning.

[Significance of molecular genetic and immunological techniques in risk groups and in children with tuberculosis]. / Znachenie molekuliarno-geneticheskikh i immunologicheskikh metodov issledovaniia v gruppakh riska i u bol'nykh tuberkulezom detei.

A total of 188 children and adolescents were examined. In all the children, blood Mycobacterium tuberculosis (MBT) DNA was determined by polymerase chain reaction (PCR) and MBT antigens (AG) and antibodies (AB) were by enzyme immunoassay. The studies have shown that it is expedient to concurrently determine MBT DNA and MBT AT in order to identify local forms of tuberculosis in children from risk groups. If the tests are positive, a comprehensive examination for tuberculosis is required; the presence of the syndrome of common disturbances is generally associated with tuberculous infection. When a local form of tuberculosis is excluded, preventive chemotherapy should be performed. Further negative tests for MBT DNA and lower MBT AT may be a criterion for the efficiency of preventive treatment. In children with tuberculosis, the results of repeated blood and urine tests for MBT DNA provide a way of evaluating the course of a tuberculous process and the efficiency of chemotherapy. PCR used to determine blood and urine MBT DNA is a highly specific test as positive results were in 79% of the children with tuberculosis.

[Kinetic model of primary processes of photosynthesis in chloroplasts. Fast phase of chlorophyll fluorescence induction under light of various intensity]. / Kineticheskaia model' pervichnykh protsessov fotosinteza v khloroplastakh. Opisanie bystroi fazy induktsii fluorestsentsii khlorofilla pri razlichnoi intensivnosti sveta.

A kinetic model was developed, which describing the system of generation and consumption of the transmembrane electrochemical proton potential delta mu H+ in primary photosynthetic processes. The model describes the catalytic cycles of photosystems I and II and the cytochrome b/f complex, as well as the ATP synthesis and passive leakage of H+, K+ [symbol: see text] Cl- ions through the thylakoid membrane. The dependence of the electron transfer rates on the value of transmembrane electric potential was taken into account. The model was applied to describe the experimental data on the registration of the fast phase of fluorescence induction. The model gives a realistic description of the fast phase of induction curves at different light intensities (from high to low).

[Regulation levels of photosynthesis processes]. / Urovni reguliatsii protsessov fotosinteza.

The basic mechanisms of kinetic regulation of photosynthetic processes are considered, which provide a strict light regulation of electron transfer in photosynthetic reaction centers and a more flexible regulation at the level of interaction of photosystems, transmembrane ion fluxes and coupling with dark reactions of the Calvin cycle. A generalized model was developed, which integrates the modern knowledge about photosynthetic processes of higher plants. The general principles of multilevel regulation in photosynthetic systems are discussed.

Kinetic mechanisms of biological regulation in photosynthetic organisms.

Principles of regulation on different levels of photosynthetic apparatus are discussed. Mathematical models of isolated photosynthetic reaction centers and general system of energy transduction in chloroplast are developed. A general approach to model these complex metabolic systems is suggested. Regulatory mechanisms in plant cell are correlated with the different patterns of fluorescence induction curve at different internal physiological states of the cells and external (environmental) conditions. Light regulation inside photosynthetic reaction centers, diffusion processes in thylakoid membrane, generation of transmembrane electrochemical potential, coupling with processes of CO(2) fixation in Calvin Cycle are considered as stages of control of energy transformation in chloroplasts in their connection with kinetic patterns of fluorescence induction curves and other spectrophotometric data.

Fluorescence induction curves registered from individual microalgae cenobiums in the process of population growth.

Registration of chlorophyll fluorescence induction curves (IC) from individual microalgae cenobiums was performed during Scenedesmus quadricauda culture growth. Emphasis was placed on the analysis of patterns of the slow phase of IC, since these slow fluorescence transitions reflect complex interactions between primary and secondary photosynthetic processes. A classification was performed of the ICs obtained according to the patterns of their slow phase. Four different types of such patterns were distinguished. The microalgae population structure with respect to IC patterns was investigated at different stages of culture growth. The distribution of microalgae cenobiums over the patterns of IC was found to change in accordance with the stage of population development. At the stage of the population growth enhancement, nonmonotonous IC dominated with a high steady-state level of fluorescence. The stage of linear growth was characterized by IC with monotonous decay kinetics and low steady-state level of fluorescence. At the third stage including the phases of growth inhibition, stationary state and the beginning of cell death the population structure was the most heterogeneous, with all IC patterns observed.

[Biological properties and antigenic interconnection between Tiuleniy and Karshi flaviviruses]. / Biologicheskie svoistva i antigennye vzaimosviazi flavivirusov tiulenii i karshi.

Biological properties of flaviviruses Tyuleny and Karshi, new for the science, were studied. The viruses are highly pathogenic for laboratory animals; they replicate fairly well in primary chick embryo cells and PS cells. BHK-21 cells were found susceptible to replication of Karshi virus. Tyuleny and Karshi viruses were found capable of initiating and maintaining a persistent infection in primary brain cell cultures from suckling Syrian hamsters for at least 3 months. Both the viruses showed cytoproliferative activity in respect of the above cells in tissue cultures. Our data indicate that Tyuleny virus, a member of a separate antigenic group, is more closely related to Japanese encephalitis virus (strain JaGar 01), and Karshi virus to Powassan virus.

[Oscillations of intracellular pH values and the character of its distribution in immunocompetent cell populations]. / Kolebaniia vnutrikletochnogo znacheniia pH i kharakter ego raspredeleniia v populiatsii immunokompetentnykh kletok.

Experimental measurements of intracellular pH kinetics detect intracellular pH (pHin) rhythms with a period about an hour and an amplitude comparable with the standard deviation of pHin in cell population. It was shown that pHin oscillations were probably to affect the experimental pH-distribution pattern. The pH-distribution of the population at normal physiological state is usually close to the normal pattern. The time-course of the pHin value for the cell population was shown to have a pattern of a kind of beatings to get the normal pH-distribution. Distributions of several "beating"--functions were used to approximate an experimental pH-distribution of immunocompetent cell population.

[The intracellular pH of the peripheral blood lymphocytes in cattle during the development of leukemia]. / Vnutrikletochnyi pH limfotsitov perifericheskoi krovi krupnogo rogatogo skota pri razvitii leikoza.

The intracellular pH distribution of peripheral cattle lymphocytes has been studied in normal state and at six stages of the development of bovine leukosis by the dye microfluorimetry of single cells. It has been shown that the increase of mean intracellular pH value occurs as well some distribution parameters, such as pH range and asymmetry change during the disease process. Probable reasons responsible for the observed modification of the distribution pattern are discussed.

[Elevated tooth abrasion in people of older age groups]. / Povyshennoe istiranie zubov u liudei starshei vozrastnoi gruppy.

Specific features of tooth abrasion were studied in 105 patients aged 46-65 with the use of special questionnaires and Smith and Knight's abrasion index. Mandibular teeth were characterized by a higher abrasion level, the first and second right molars wearing down the first. Of the maxillary teeth the frontal ones were worse worn down. Potable water enrichment with fluorine (up to 2 mg/l) did not reduce the level of teeth abrasion.

[Changes in the amount and synthesis of DNA in the nuclei of large decidual cells in rats during their differentiation]. / Izmenenie kolichestva i sinteza DNK v iadrakh bol'shikh detsidual'nykhkletok krys v khode ikh differentsirovki.

Using cytophotometry of the Feulgen-stained nuclei, the quantity of DNA was measured in the nuclei of rat's large decidua cells (LDC) on tissue sections of the antimesometrial region within days 7-13 of gestation. The quantity of nuclear DNA was expressed in units of ploidy, the haploid DNA standard being the quantity of DNA in rat's spermatid nucleus. On different days of gestation, the nuclear DNA was seen to vary in cells located in different zones of decidua. The maximum DNA content was found in the LDC located on days 9-12 of gestation somewhat in the middle of the decidua thickness. On day 11, the quantity of nuclear DNA in these cells reached in average, 22c. The quantity of DNA in the nuclei of the least differentiated LDC located on the periphery of decidua never exceeded 4.9c, whereas that in the nuclei of the most differentiated LDC, located close to the embryo, varied from 2.9c to 9.3c. On days 10 and 11 of rat's false gestation, the maximum DNA contents in the nuclei were registered in the LDC located in the middle of the decidua thickness. 3H-thymidine incorporation into the nuclei of the most differentiated LDC located nearest to the embryo stopped starting from day 10 of gestation. Phenomena of lesser quantities of nuclear DNA in most differentiated LDC, compared to that in LDC in the previous steps of differentiation, are discussed.

[Incorporation of 3H-uridine into the large decidual cells of rats and their differentiation]. / Vkliuchenie 3H-uridina v bol'shie detsidual'nye kletki krys i differentsirovka étikh kletok.

The antimesometrial part of rat's decidua of the 9th day of gestation was divided into three zones. Cells of either zone display their own morphological and cytochemical properties. Different rates of 3H-uridine incorporation were observed in the cytoplasm and the nucleus in cells of either zone during 5, 30, 60 and 240 minutes after precursor injection. The largest member of silver grain accumulation was observed in the karyoplasm and nucleolus of cells of the transitional zone. The nucleus of basal zone cells had the smallest intensity of 3H-uridine incorporation. The nuclei of the epithelial zone cells are characterized by a lower intensity of 3H-uridine incorporation than those of the transition zone. The intensity to cytoplasmic accumulation of silver grains raised from cells of the basal zone up to cells of the epithelial zone. The largest quantity of cytoplasmic radioactivity was observed 240 minutes after 3H-uridine injection.

[Dynamic modelling of the simazine content of soil]. / Modelirovanie dinamiki soderzhaniia simazina v pochve.

A mathematical model of dynamics of simazine level in soil based on the hypothesis of several forms of simazine in soil and integral influence of environmental factors on inactivation has been worked out. The results of modelling are under discussion.

[Monoclonal immunoglobulins to the antigens of the Japanese encephalitis virus]. / Monoklonal'nye immunoglobuliny k antigenam virusa iaponskogo éntsefalita.

Six hybridomas of the EJ series producing monoclonal antibodies to Japanese encephalitis virus antigens were generated by hybridization of immune splenocytes with the parental line of mouse myeloma cells NS-0, and one hybridoma (EJ-10) with the X63-Ag8/653 line. Among 7 species of monoclonal antibodies examined by Ouchterlony method, 3 were identified as IgM and 4 as IgG. The highest clone-producing efficacy was shown by hybridoma EJ-10 generated on the basis of X-653 cells and the least by hybridoma EJ-20. The hybrid cells readily established in the cavity of mice producing ascitic tumors in 37%-86% cases. Among the derived clones, two were found, EJ-4 (IgG) and EJ-19 (IgM), to possess a high growth potential, satisfactory clone-producing efficacy, a high per cent of positive clones in recloning, and stable production of antiviral monoclonal antibody. Hybridomas EJ-4 and EJ-19 demonstrated a marked capacity for mouse-to-mouse transmission in serial passages providing for preparative accumulation of these monospecific immunoglobulins.