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Biomedical subjects

V N Buneva

Publications and source records attributed to V N Buneva.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Multiplicity of affinity modification of RNAse during its alkylation with a reactive analog of 5-deoxyribonucleotide].

The interaction of pancreatic RNase with 5'-deoxyribodinucleotide alkylating derivative, 4-(N-2-chloroethyl-N-methylamino)benzylamide of d(pTpA) d[(ClRCH2NH)pTpA], was studied. The unreactive oxyanalogue d[(HORCH2NH)pTpA] was shown to act as competitive inhibitor of cCMP hydrolysis by RNase. d[(ClRCH2NH)pTpA] irreversibly inactivated RNase. A protective effect was exerted by d(pTpA) and d[(HORCH2NH)pTpA]. The modification, although having an affinity character, was not accompanied by total inactivation of the enzyme. It was supposed that covalent bonding between the reagent and enzyme induced the dinucleotide displacement from the recognition site. The formation of four RNase monolabeled forms retaining the activity in the hydrolysis of cCMP and poly(U) was demonstrated.

Alkylating Agents↗
PubMed1980

[Interactions of yeast hexokinase with ATP and AMP 4-(N-2-chloroethyl-N-methylamino)benzylamidates].

The interactions of ATP and AMP 4-(N-2-chloroethyl-N-methylamino)-benzylamidates with yeast hexokinase were studied. It was found that the ATP analog does not interact with hexokinase. The AMP analog irreversibly and almost completely inactivates hexokinse. A strong protective effect is exerted by MgATP. The value of apparent Ki for the AMP analog is equal to 2.10(4) M. The existence of affinity modification is postulated.

Adenosine Monophosphate↗
PubMed1980

[Interaction of rabbit muscle creatine kinase with a reactive ATP derivative-ATP gamma-4(N-2-chloroethyl-N-methyl-amino)-benzylamidate].

The interaction of AGP gamma-4(N-2-chloroethyl-N-methyl-amino)-benzylamidate with rabbit muscle creatine kinase was studied. ATP gamma-4-(N-2-hydroxyethyl-N-methyl-amino)-benzylamidate acts as competitive inhibitor of creatine kinase. The Km value for ATP and the Ki value for the gamma-analog have been determined. A complete inactivation is observed when 1 mole of the reagent binds per 1 mole of the enzyme. The modification of the second subunit of creatine kinase is achieved at higher concentrations of the reactive ATP analog. The reactive ATP derivative is shown to be an affinity reagent for this enzyme. The possibility of interaction between the subunits of creatine kinase is discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

[The mechanism of the supercoiled DNA recognition by eukaryotic type I topoisomerases. I. The enzyme interaction with nonspecific oligonucleotides].

Interaction of the DNA type I topoisomerases from the murine and human placenta cells with nonspecific oligonucleotides was analyzed. The contributions of strong and week nonspecific electrostatic, van der Waals's, and hydrophobic interactions, and hydrogen bonding of the enzymes to the complex formation with the single- and double-stranded DNAs were determined. The factors that determine the top-priority recognition of the topologically stressed DNA were revealed. The results were interpreted in comparison with the X-ray analysis data for human DNA topoisomerase I.

Animals↗
PubMedDate not supplied

[The mechanism of supercoiled DNA recognition by eukaryotic type I topoisomerases. II. A comparison of the enzyme interaction with specific and nonspecific oligonucleotides].

Data on the interaction of DNA type I topoisomerases from the murine and human placenta cells with specific and nonspecific oligonucleotides of various structures and lengths are summarized. The relative contributions of various contacts between the enzymes and DNA that have previously been detected by X-ray analysis to the total affinity of the topoisomerases for DNA substrates are estimated. Factors that determine the differences in the enzyme interactions with specific and nonspecific single- and double-stranded DNAs are revealed. The results of the X-ray analysis of human DNA topoisomerase I are interpreted taking into account data on the comprehensive thermodynamic and kinetic analysis of the enzyme interaction with the specific and nonspecific DNAs.

Animals↗
PubMedDate not supplied

Secretory immunoglobulin A from healthy human mothers' milk catalyzes nucleic acid hydrolysis.

The human milk secretory immune system is the first line of protection for the newborn infant against various pathogens. Secretory IgA (sIgA), the typical immunoglobulin found in secretions, can fight infections through many mechanisms. Using different methods, we have shown that sIgA from the milk of healthy women possesses DNAse and RNAse activities. The catalytic center is localized in the light chain of catalytic sIgA, while the DNA-binding center is predominantly formed by its heavy chain. The enzymic properties and substrate specificity of catalytic sIgA distinguish it from other known DNases and RNases. It is reasonable to assume that the milk DNA- and RNA-hydrolyzing antibodies are capable not only of neutralizing viral and bacterial nucleic acids by binding these antigens as well as by hydrolyzing them. The DNA-hydrolyzing activity of Abs raises the possibility that these catalytic Abs may provide protective functions for the newborn through the hydrolysis of viral and bacterial nucleic acids.

Antibodies, Catalytic↗
PubMedDate not supplied

Catalytic heterogenity of polyclonal RNA-hydrolyzing IgM from sera of patients with lupus erythematosus.

Various catalytically active IgG antibodies or abzymes have been detected recently in the sera of patients with several autoimmune pathologies including systemic lupus erythematosus (SLE), where their presence is most probably associated with autoimmunization. Here we show for the first time that IgM from peripheral blood of patients with SLE possesses both DNase and RNase activities: these activities were also present in Fab fragments of the IgM. Both specific enzymic activities of IgM from sera of any single patient are usually 5-10 times higher than those of IgG antibodies. The same preparations of IgM hydrolyze RNA about two order of magnitude faster than DNA. The properties of the RNases of IgM and IgG distinguished them from other known pancreatic and human sera RNases. In addition, the specific activities of the RNase activity of polyclonal IgM with the polymer substrates [RNA > poly(U) > or = poly(A) >> poly(C)], the observed range of optimal pHs, of apparent Km values for substrates and of substrate specificities varied very much for different patients. The findings speak in favor of the generation of a relatively small or an extremely large pool of polyclonal catalytic IgM by the immune system of individual patients.

Antibodies, Catalytic↗
PubMedDate not supplied

Effect of different drugs on the level of DNA-hydrolyzing polyclonal IgG antibodies in sera of patients with Hashimoto's thyroiditis and nontoxic nodal goiter.

BACKGROUND: DNA-hydrolyzing IgG antibodies have been detected recently in the sera of patients with several autoimmune diseases. MATERIAL AND METHODS: The relative activity of DNA-hydrolyzing IgG from the sera of patients with Hashimoto's thyroiditis and with non-toxic nodal goiter as a function of the patient's condition were measured. The effect of different drugs on the level of DNA-hydrolyzing IgG, functional activity of thyroid gland, and improvement of clinical condition of two groups of patients were analyzed. RESULTS: We demonstrate here for the first time that IgG from peripheral blood of patients with Hashimoto's thyroiditis (65%) and non-toxic nodal goiter (38%) possesses DNAse activity. The relative level-specific activity of IgGs in hydrolysis of DNA increases with the enhancement of the relative amount of antibodies against thyroglobulin and all patients with hypothyroidism (namely a reduced concentration of thyroxine and triiodothyronine and enhanced level of thyrotropic hormone) are characterized by a high level of catalytic antibodies. CONCLUSIONS: The very widely used therapy of patients with thyroxine led only to a temporary change of the hormone concentration in the blood but did not affect the level of DNA-hydrolyzing antibodies. However, treatment with an immunosuppressive drug plaquenil (7-chloro-4(beta-diethylamine-alpha-methylbutylamie)quinoline), significantly decreased the DNA-hydrolyzing activity of Abs, which correlated with enhancement of thyroid hormone concentrations, elevation of functional activity of the thyroid gland, and improvement of the clinical state of the patients.

Antibodies, Antinuclear↗
PubMedDate not supplied

[Assessment of the status of biological health of the population of tundra Nentsy inhabiting northwestern Siberia from data on analysis of autoantibodies and lipoproteins from blood donors].

As a result of large-scale nuclear explosion on Novaya Zemlya test site (1955-62) the Tundra Nentsy population of Yamal-Nentsy autonomous region (YNAR) fell under constant influence of incorporated radioactive isotopes (137Cs and 90Sr). Therefore, it is very important to analyze a possible spectrum of diseases of Tundra Nentsy population. We have developed recently a new method for determination of concentrations of all main fraction and subfraction of lipoproteins (LP, 30 parameters) in human sera using small-angle X-ray scattering, and a general mathematical model to describe LP composition in human blood. The analysis of the 30 parameters characterizing fine spectrum of LPs in 374 YNAR natives showed that only approximately 10% of the donors are normal, while the indices for approximately 90% of the test subjects fall into the range of different pathologies (3-8% incidence in normal population, according to epidemiological studies). Moreover, we found that approximately 41% of European and approximately 56% of Tundra Nentsy have high level of autoantibodies to DNA and cardiolopine like the same for autoimmune diseases patients.

Autoantibodies↗
PubMedDate not supplied

[The mechanism of specific cleavage of supercoiled DNA by human DNA topoisomerase I: the effect of ligand structure on the catalytic step of reaction].

Eukaryotic DNA topoisomerase I (Topo) regulates the topological state of cell DNA and plays an important part in replication, transcription, repair, and recombination. Factors affecting the specific recognition of topologically stressed DNA were analyzed on the basis of the thermodynamic and kinetic data on the Topo-DNA interaction and the X-ray data on human Topo. A model was advanced for possible structural changes occurring in the ligand after initial recognition. The effect of conformational changes in specific DNA on the catalytic stage of the reaction was analyzed.

Catalysis↗
PubMedDate not supplied

[Antibodies to DNA in the blood of patients with tick-borne encephalitis].

A comparison of relative levels of autoantibodies (Abs) to both native (n) and denatured (d) DNA in the blood of 55 patients with tick-borne encephalitis (TBE) was carried out. 31% of patients with TBE was shown to have an increased level Abs to nDNA and 40% of patients demonstrate increased level of Abs to dDNA. The percent of TBE patients with increased concentration of anti-nDNA Abs higher then that in patients with multiple sclerosis (18%) and some other autoimmune diseases (6-18%), but comparable with that for patients with systemic lupus erythematosus (38%) and polymyositis (42%). In contrast to patients with systemic lupus erythematosus and multiple sclerosis, the level of Abs to nDNA in patients with TBE is higher than the level of Abs to dDNA. Correlation coefficients of Ab levels to both n- and dDNA were estimated for group of patients in whole and for separate subgroups with different type of disease (temperature reaction, feverishness and meningitis). Analysis of correlation between titres of anti-DNA Abs and three standard biochemical markers of TBE (activity of aspartate- and alanine-aminotransferases, and concentration of whole bilirubin) for 22 patients with TBE was carried out. Statistically significant correlation was revealed only between the level of Abs to nDNA and activities of aspartate- and alanine-aminotransferases, correlation coefficients are equal to +0.44 and +0.48, respectively.

Antibodies, Viral↗