The role of bivalent cations in the binding of hexokinase II isoenzyme to mitochondrial membranes

A comparative study of Mg2+ and Ca2+ effects on the ability of rat skeletal muscle hexokinase isozyme II to bind mitochondrial membranes isolated from the same source was carried out. It was found that the binding ability of the enzyme increases in a similar way in the presence of equimolar amounts of both cations. The dependence of binding ability on cation concentration is hyperbolic, which points to the existence of specific and equivalent metal binding sites during hexokinase attachment to the membranes. Substitution of Ca2+ for Mg2+ does not influence the tightness of the enzyme binding to membranes, which can be evidenced from the type of dependence of the bound hexokinase solubilization degree on KCl concentration in the eluting buffer. The enzyme absorption mediated by various cations is accompanied by corresponding changes in its kinetic properties (V, Km for glucose, Ki for ADP). The role of bivalent cations in the formation of the specific hexokinase-membrane binding is discussed.     

Genetic Predisposition to Early Myocardial Infarction

Molecular Biology - The aim of the study was to identify the features of the genetic structure of myocardial infarction (MI) susceptibility depending on age (“early MI” denoting...     

Neutralizing single-chain antibodies against the tick-borne encephalitis virus

A recombinant pSC13D6 plasmid DNA was constructed based on cDNA fragments of genes encoding variable domains of heavy and light chains of the MKA13D6 monoclonal antibody against glycoprotein of the tick-borne encephalitis (TBE) virus. This plasmid provided expression in Escherichia coli cells of the scl3D6 single-chain antibody against the TBE virus. The produced antibodies could bind to the TBE virus, strain 205, and the TBE virus recombinant E protein. The affinity constant of purified scl3D6 was (3.0 ± 0.2) × 10⁷ M^?1 for the equilibrium state and (2.8 ± 0.3) × 10⁷ M^?1 in the case of antigen-antibody formation on the surface. The obtained single-chain antibody could inhibit the infection potency of the TBE virus on a monolayer of eukaryotic cells. The calculated IC₅₀ value for scl3D6 was 16.7 μg/ml.     

Influence of the professional activity of pilots on the adaptive pattern of hemodynamic reactions to the tilt test

A comparative study of the blood circulation??s response to the tilt test was performed in three groups of healthy subjects: AF pilots (n = 72), engine drivers (n = 44), and students at the Military Institute of Radio Electronics (n = 32). In all the groups, adequate adaptive responses to the test were recorded under eukinetic hemodynamics where steady cardiac output and blood pressure values combined with an increase of the heart rate by 10?C12%. Hypokinetic hemodynamics caused a 20% increase in cardiac output during the initial 5 min of orthostasis in pilots versus an 8?C12% increase in the others. Hyperkinetic hemodynamics were responsible for the increase in the cardiac output in pilots but not in the other groups. Parasympathetic system activation was peculiar of hypokinetic hemodynamics, while sympathetic system activation was associated with hyperkinetic hemodynamics. These results suggest a larger body functional reserve in pilots compared to other subjects as a side effect of their profession.     

Growth of Azotobacter chroococcum strains on different substrates]

Azotobacter chroococcum 34, actively growing on alpha-ketoglutaric acid, and Azotobacter chroococcum B and KL, which almost do not assimilate this acid, can grow on the majority of substrates of the tricarboxylic acid cycle and on glucose, with and without nitrogen. The rate of assimilation of alpha-ketoglutaric acid is several times higher in the cells cultivated in the presence of this acid than in the cells grown on other substrates. This difference seems to involve the mechanism of transport of alpha-ketoglutaric acid into the cell.     

The parthenogenetic activation under the action of cycloheximide of mouse oocytes matured in vivo

Treatment of mouse oocytes matured in vivo by cycloheximide at a concentration 25 micrograms/ml for 2 h induced female pronucleus formation. In all activated oocytes the formation of the female nucleus was completed 5-6 h after the beginning of cycloheximide treatment. When cycloheximide concentration was decreased down to 5 micrograms/ml, its effect was detected 1 h later as compared with that at a concentration of 25 micrograms/ml.