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T M Tret'iak

Publications and source records attributed to T M Tret'iak.

At least 19 recordsLinked to original sources
PubMed1988

[Effect of catecholamines and serotonin on RNA-synthesizing activity in isolated nuclei and chromatin of the rat brain and liver].

It has been shown that intraperitoneal injections of L-DOPA cause an increase in the matrix activity of chromatin and stimulate the incorporation of [3H]uridine into the nuclear fraction of rat brain cells by 35%. In vitro studies have shown that preincubation of brain chromatin with L-DOPA diminishes the inhibiting effect of actinomycin D on RNA synthesis. It has been found that the rate of RNA synthesis in vitro depends on concentrations of catecholamines (L-DOPA, dopamine, norepinephrine) and serotonin.

Animals↗
PubMed1987

[Characteristics of the complex formation of L-DOPA with chromatin elements from brain cells].

It was found that L-DOPA interacts with brain cell chromatin. The life-time of the chromatin-L-DOPA complex is the greatest at 24 degrees C, while at 37 degrees C the destruction of the complex is observed. The specific binding is about 40% at pH 7.4-7.6. The Kd value calculated by the method of Scatchard is equal to 35.10(-9) M. Treatment of the chromatin-L-DOPA complex with DNAase I decreases the chromatin radioactivity by 15-20%. At the same time pronase treatment decreases the chromatin radioactivity by 80%. NaCl (0.2 and 0.4 M) causes the extraction of more than 70% of 3H-DOPA in the complex with chromatin proteins. Thus, L-DOPA interacts predominantly with chromatin proteins.

Animals↗
PubMed1987

[DNA repair in mammalian nerve cells. I. DNA synthesis in the neocortex of rats induced by gamma irradiation].

A study was made of the DNA synthesis in cerebral cortex of rats, aged 14 and 60 days, after gamma-irradiation in vivo in a dose of 7 Gy, the 3H-thymidine incorporation into DNA being determined.137 Cs-radiation induces additional DNA synthesis in the neocortex tissue and in neurons. In the cortex of 14 day-old rats, the induced DNA synthesis stops 2 hours after irradiation, whereas in the cortex of 60 day-old rats and in neurons of rats of both the age groups DNA synthesis is proceeding for 3-3.5 hours. Specificity of DNA reparation processes in non-dividing cells is discussed.

Aging↗
PubMed1987

[Mechanism of action of DNAse from the rat brain].

The mechanism of action of exodeoxyribonuclease from rat brain predominantly localized in neuronal nuclei was studied. The enzyme which is highly specific towards one-chain DNA can effectively hydrolyze the two-chain DNA of plasmid pBR 322 "activated" by the disruption of the phosphodiester bond in one chain. A kinetic analysis of DNA hydrolysis with a tritium label evenly distributed along the DNA molecule and terminally labeled with phosphate revealed that the enzyme hydrolyzes polynucleotides from the 5'-to the 3'-end via a partially processive mechanism.

Animals↗
PubMed1982

[Characterization of DNAse from rat brain].

Using gel filtration and ion exchange chromatography, a DNAse specific to a single-stranded DNA was isolated from the soluble fraction of rat brain nuclear proteins. The nuclear nuclease corresponds to alkaline DNAse obtained earlier from the intact brain. The enzyme is a Mg2+- or Mn2+-dependent exodeoxyribonuclease and hydrolyzes at the same rates the ss-DNAse from rat brain, calf thymus, E. coli and poly (dA). The major products of hydrolysis are nucleoside-5'-monophosphates. A possible role of the enzyme in reparation of neuronal DNA is discussed.

Animals↗
PubMed1980

[Alkaline DNAse from rat brain].

A DNAse was isolated from rat brain and purified 1100-fold using affinity chromatography on a column with DNA-agarose and chromatography on granulated hydroxyapatite. The electrophoretically pure Mg2+, Mn2+-dependent enzyme preparation hydrolyzes the denaturated DNA with a maximal activity at pH 8,4. The optimal terminal concentration of Mg2+ corresponds to the Mg/phosphorus molar ratio of the substrate is 1:2. For Mn2+ this correlation is 1:1. Using the immobilized substrate method, the exonuclease type of DNAse activity has been established. The enzyme activity depends on the state of its SH-groups; the reaction is inhibited by pCMB. The molecular weight of DNAase as determined by gel-filtration through Sephadex G-200 is equal to 60 000.

Animals↗
PubMed1979

[Rat brain nuclease activity during learning with emotionally different reinforcement].

Acid and alkaline activity of nucleases of the rats trained with emotional positive or negative reinforcement was estimated in the neocortex, hippocampus, midbrain, and in caudal portions of the brain-stem, using native and denaturated DNA as a substrate. The results showed the total increase in nuclease activity during learning. Nevertheless the dynamics of enzyme activation was different depending on the emotional state of rats during learning. The most active enzyme was found in the caudal portion of the brain-stem.

Animals↗
PubMed1977

[Study of rat brain tissue nucleases].

Acid and alkaline nucleases of the brain tissues have been identified and partially purified. Alkaline DNA-ase hydrolyzing denatured DNA at pH 8,0; alkaline RNA-ase having optimal activity at pH 8,0 and nuclease intensively hydrolyzing both DNA and RNA at pH 5.0. The molecular weights of these enzymes have been determined.

Animals↗
PubMedDate not supplied

[Conjugates of pancreatic ribonuclease and ligand-free human serum albumin].

Conjugates of pancreatic RNase and ligand-free human serum albumin (LFHSA) have been obtained. The number of hydrophobic binding sites both for initial HSA and LFHSA has been determined by the polarised luminescence method. Interaction between RNase and HSA involves additional electrovalent linkage. Unlike initial enzyme, conjugates exhibit activity toward double-strand RNA. After intravenous injection, transferase activity of unmodified enzyme remains in the blood during 20 min., whereas 30-40% of this activity is detected at the fourth day after administration of RNase conjugates. A single dose administration of LFHSA-RNAse conjugates exhibited high antiviral activity in mice, infected with influenza A and influenza B viruses.

Animals↗