Biomedical subjects
Publications and source records attributed to M K Nurbekov.
1-Ethoxysilatrane and 1-isopropoxygermatrane stimulated liver regeneration via activation of some components of the protein-synthesizing complex, in particular, aminoacyl-tRNA synthetases. Acylating activity of aminoacyl-tRNA synthetases increased. Possible mechanisms of these changes are discussed.
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The cos-site of lambda phage from pHC79 cosmide is transferred to DNA from M13 mp18 phage. The recombinant DNA thus obtained (MC18) is efficiently packaged into lambda proteins in vitro. The BamHI-HindIII fragment of pGP588 (a pBR322 derivatives containing fragment of human DNA) is subcloned into MC18. Although this pGP588 fragment contains numerous Alu repeats, no essential rearrangements of the insert were revealed. The efficiency infection by recombinant DNA packaged with lambda proteins is about 1 X 10(5) pfu/microgram DNA, whereas in the similar conditions the efficiency of lambda EMBL3A was 1 X 10(6) pfu/microgram. It is assumed that the MC vectors might be suitable for cloning and sequencing large fragments either with cohesive or blunt ends. It opens also the way to construct genomic libraries in single-stranded phages.
As is found by atomic absorption spectroscopy, the highly purified bovine tryptophanyl-tRNA synthetase contains up to 0.9 mol Zn2+/mol enzyme while some other bivalent metal ions are absent. The enzyme is inactivated either upon treatment with 1,10-phenanthroline (a zinc-chelating agent) or upon prolonged dialysis (which eliminates bound Zn2+ ions); addition of zinc reactivates the enzyme. Exposed histidine residue(s) and carboxylic group(s) of the enzyme are involved in the Zn2+ binding, as is shown using chemical modification. Circular dichroism spectra suggest that elimination of Zn2+ ions affects the tertiary rather than the secondary structure of the tryptophanyl-tRNA synthetase. The kinetics of inhibition with 1,10-phenanthroline toward ATP, tryptophan and tRNATrp indicates that removal of zinc prevents the ATP binding to the enzyme.
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In the condition of prolonged group sex starvation of rats variations were seen in behavioral reactions, fertility, extent of weight gain, litter, blood alpha-tocopherol level, eosinophil count, lipid peroxidation, evoked brain potentials. All these processes are the sign of stress development in rats. Thus, stress in mature rats influences litter and fertility, newborn rats had underdeveloped nervous system. Changes in the activity of endogenic antioxidant system in this experiment are discussed.
Crystals of leucinaminopeptidase from bovine pancreas were obtained. Space group (P6322), parameters of the cell a-b-132 A, c = 122 A and distribution of spot intensities on precessional X-ray patterns were in full agreement with corresponding parameters for leucinaminopeptidase crystals from bovine eye lens. A conclusion is drawn about similarity between the spatial structures of leucinaminopeptidase from bovine pancreas and eye lens.
The possibility of participation of covalent enzyme substrate's derivatives in reactions catalyzed by aminoacyl-tRNA synthetases is discussed in connection with general principles of enzyme catalysis. Tryptophanylated and pyrophosphorylated forms of beef pancreas tryptophanyl-tRNA synthetase were identified, isolated and characterized and the expected role of these derivatives in the enzyme function is discussed.
By means of atomic absorption spectroscopy up to 0.9 Zn2+ atom per molecule of bovine tryptophanyl-tRNA-synthetase (E. C. 6.1.1.2) was found. Treatment of the enzyme with orthophenanthroline (Zn2+-chelating agent) or prolonged dialysis leading to the removal of bound Zn2+ causes inactivation of the enzyme whereas the addition of Zn2+ reactivates it. Kinetic analysis of the inhibiting action of orthophenanthroline at various concentrations of tryptophan, ATP and tRNA leads to the conclusion that removal of Zn2+ prevents the binding of the ATP molecule to tryptophanyl-tRNA-synthetase. By means of chemical modification it is shown that exposed histidine residues and the carboxylic groups of the enzyme participate in Zn2+ binding. According to circular dichroism data removal of Zn2+ has no influence on the secondary structure although some local alterations of the ternary structure are revealed.