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Biomedical subjects

V G Budker

Publications and source records attributed to V G Budker.

At least 55 records · Page 3Linked to original sources
PubMed1979

Activated forms of oxygen in the metabolism of xenobiotics catalyzed by cytochrome P-450.

The Cu(Lys)2 complex is shown to be an effective inhibitor of the oxidation of 3,4-benzpyrene and aniline in microsomes. Apparently, this is due to the dismutation of superoxide radicals involved in the metabolism of these compounds. Possible interactions between Cu(Lys)2 and model membranes have been studied using spin probes. A model has been suggested according to which Cu(Lys)2 "builds" in the membrane hydrocarbon regions.

Aniline Compounds↗
PubMed1978

[Spatial proximity of the ribosomal mRNA binding center to the 50S subunit].

4-(N-2-chloroethyl-N-methylamino)benzylamide of 5'-heptaadenylic acid was used for affinity labelling of the ribosome in the vicinity of its mRNA-binding centre. This derivative, similar to the free oligonucleotide, stimulates the binding of [14C]-lysyl-tRNA to ribosomes of E. coli and alkylates ribosomes both the 30S and the 50S subunits. The alkylation of ribosomes is inhibited by pre-incubation of ribosomes with polyadenylic acid, which suggests that the chemical modification is a specific one and occurs in the vicinity of mRNA-binding site. The fact, that a short oligonucleotide having an active group on its 5'end attacks the 50S subunit of ribosome may indicate that the mRNA-binding centre is located in the contact region between ribosomal subunits.

Affinity Labels↗
PubMed1978

[Interaction between polynucleotides and mitochondria from rat liver].

The interaction between labelled polynucleotides and the mitochondrial membrane was studied. It was shown that DNA and mRNA form a complex with the mitochondria and mitoplasts (i. e. mitochondria devoid of the outer membrane); this process does not depend on the energy state of mitochondria. Within the complex polynucleotides are accessible to the effects of nucleases. The complex formation strongly depends on the concentration of Mg2+ and is inhibited by Na+. It was found that polynucleotides are effectively bound to protein-free artificial membranes isolated from the total mitochondrial lipids. The data obtained suggest that in the presence of Mg2+ polynucleotides form a complex with the lipid components of the mitochondrial membrane.

Animals↗
PubMed1977

Detection of the kinetics of biochemical reactions with oxygen using exchange broadening in the ESR spectra of nitroxide radicals.

To detect changes in the oxygen concentration during biochemical reactions, the exchange broadening in the ESR spectra of nitroxide radicals caused by the dissolved oxygen, has been used. The measurements have been carried out using changes in the width either of the proton hyperfine structure components or of the nitrogen hyperfine structure line with an unresolved proton structure. Detection of mitochondrial respiration in a volume of about 10(-3) cm 3 and respiration for 100 +/- 5 liver cells in a volume of about 10(-4) cm3 has been carried out.

Electron Spin Resonance Spectroscopy↗
PubMed1976

[Preparatory extraction of 5'-oligoribonucleotides using ribonuclease from cobra venom].

Cobra (Naja oxiana) venom ribonuclease, which catalyses hydrolysis of polyribonucleotides to 5'-oligonucleotides, was used to obtain preparatively isoplit oligonucleotide fractions, containing 2-30 nucleotides. The yield of hydrolysis products varied depending on the degree of hydrolysis. Hydrolysis rates of different polynucleotides were studied. Hydrolysis rate of polyadenylic acid was 20 times as high as that for polyuridylic acid. Quantitative ratios of isoplit fractions did not vary significantly under similar degree of hydrolysis of polyadenylic and polyuridilic acids. Chromatography on QAE-Sepahdex in ammonium bicarbonate concentration gradient containing 15% dioxan was used to separate enzymatic hydrolysates of polynucleotides, which permitted to bring the fraction isolation to simple evaporation.

Animals↗
PubMedDate not supplied

Caged DNA does not aggregate in high ionic strength solutions.

The assembly of DNA into compact particles that do not aggregate in physiologic salt solution occurs naturally in chromatin and viral particles but has been challenging to duplicate using artificial constructs. Cross-linking amino-containing polycations in the presence of DNA with bisimidoester cross-linker leads to the formation of caged DNA particles that are stable in salt solutions. This first demonstration of caged DNA provides insight into how natural condensation processes avoid aggregation and a promising avenue for developing nonviral gene therapy vectors.

Cross-Linking Reagents↗
PubMedDate not supplied

[The effect of mRNA on the stability of the ribosome--aminoacyl-tRNA complex].

The effect of some olygo- and polynucleotides on the dissociation rate of the 14C-aminoacyl-tRNA - ribosome complex was investigated. Polyuridylic and polycytidylic acids were shown to accelerate significantly dissociation of the complex of lysyl- and phenylalanyl-tRNA with native ribosomes, but not to affect the complexes of these aminoacyl-tRNA's with 50S subunits. It is proposed that the template polynucleotides decrease the affinity of ribosomes to tRNA by association with the mRNA-binding site on 30S subunits.

Binding Sites↗
PubMedDate not supplied

[Mg2+-dependent interaction of DNA with eukaryotic cells].

Interaction of DNA with eukaryotic cells under conditions similar to those providing DNA adsorption onto liposomes was studied. It was revealed that mouse fibroblasts (line A9) and myeloma cells bind phage and plasmid DNA in 0.3 M sucrose solution containing Mg2+-ions. Additional pretreatment of the cells by trypsin did not affect DNA adsorption efficiency. The major part of the adsorbed DNA recovered by salt treatment of the cells, but 10-15% of DNA was found to be irreversible. Up to 50% of the irreversibly bound DNA molecules retain their linear size after treatment of cells with DNAse I. Efficiencies of DNA adsorption and irreversibly binding depend on the concentration of Mg2+ in the medium. The process of DNA irreversible binding is not inhibited by drugs affecting cell metabolism. It is assumed that DNA adsorbs onto the phospholipid domains of the cell membrane, and part of the adsorbed DNA is taken up into the interior of the cells.

Animals↗
PubMedDate not supplied

[Release of proteins from metaphase chromosomes induced by lipid membranes].

The interaction of the isolated chromosomes with the model phospholipid membranes in the presence of divalent cations leads to chromosomal decondensation as we showed previously by using different methods. In this manuscript we report data concerning the mechanism of such membrane-promoted decondensation. Under the action of liposomes at least three proteins are released from the chromosomes. The appearance of these chromosomal proteins was detected by SDS-electrophoresis of the fraction of the liposomes after dissociation of the complexes. One of these proteins with MW 33 kDa is tightly bound with the liposomes while the other two with MW 25 and 68 kDa release without binding. We suggested that the chromosomal decondensation at mitosis is caused by the action of the newly formed nuclear envelope, in particular by its membrane part which is able to provide the release of chromosomal proteins responsible for keeping the chromosomes in the compact state.

Animals↗
PubMedDate not supplied

[Affinity modification of Escherichia coli ribosomes in the region of the mRNA-binding center by a heptauridylate analog bearing a chemically active group at the 3' end].

4-(N-2-chloroethyl-N-methylamino)-benzaldehyde acetyl derivative (RCL-derivative) of hepatauridylic acid was used to localize the structure organizing the mRNA-binding site of ribosomes. This derivative; like a free oligonucleotide, stimulates the binding of [14C]phenylalanyl-tRNA to ribosomes and effectively alkylates ribosomes, mainly the 30S subunit within the specific complex. The alkylation being completely inhibited by preincubation with polyuridylic acid, suggests that the chemical alteration occurs near the mRNA-binding site. Both rRNA and proteins undergo modification in the 30S subunit (15 and 85% of the total 30S subunit, respectively). The radioactive marked was found in fractions of proteins S18, S9 and S1.

Affinity Labels↗