[Thermodynamic behaviour and conformational changes of alcohol oxidase of yeasts Hansenula polymorpha].

We studied influence of heating, ethanol and sodium azide on the structural and conformational changes of the alcohol oxidase from yeast Hansenula polymorpha. The increase of fluorescence of alcohol oxidase -cofactor, flavin adenine dinucleotide, was revealed when heated to 60 degrees C while the enzymatic activity of alcohol oxidase remained unchanged. Differential scanning microcalorimetry revealed that ethanol stabilized the protein structure and increased the temperature of melting, Based on the data of circular dichroism, we concluded that the percentage of helicities in the secondary structure of alcohol oxidase was not influenced by both ethanol and sodium azide, however ethanol significantly modified the circular dichroism spectrum associated with the tertiary structure of alcohol oxidase.

[Immunological characteristics of Aujeszky's disease virus glycoprotein].

A panel of monoclonal antibodies (MAbs) specific to glycoprotein D (gD) of Aujeszky's disease virus (ADV, Suid herpesvirus 1) was produced and characterized. MAbs were used to identify 9 topologically different epitopes and epitopic groups on gD. The majority of the identified epitopes were conformational. Most gD-specific MAbs possessed virus-neutralizing activity in the presence and absence of the complement. MAbs neutralized the virus at the stage of its penetration into the cell and inhibited the cell-to-cell spread of viruses. Two immunodominant epitopes and one immunodominant domain that induce the most prominent humoral immune response were identified when the animals were infected and immunized. A method was developed for affinity purification of ADV glycoprotein D. Immunization of mice with affinity-purified gD induced a strong humoral immune response and protected mice against lethal ADV challenge. In passive immunization, the majority of gD-specific MAbs protected mice against infection. The findings confirm the important role of ADV glycoprotein D in inducing protective anti-ADV immunity.

[Effect of GDP and carboxyatractylate on potassium ion transport in brown fat mitochondria]. / Vliianie GDP i karboksiatraktilata na transport ionov kaliia v mitokhondriiakh burogo zhira.

It has been shown that the increase of the membrane potential in uncoupled brown fat mitochondria after addition of 1-2 mM GDP to a medium containing potassium acetate is accompanied by swelling of mitochondria which occurs in two phases. The first swelling phase is due to the electrogenic transport of K+ ions, while the second one is activated by carboxyatractylate and carnitine. The swelling is practically completely inhibited by a further rise of the GDP concentration irrespective of high values of the membrane potential. Unlike K+ transport, the potential-dependent transport of Na+ ions occurs more rapidly, is monophasic and insensitive to carboxyatractylate and carnitine. It is suggested that regulation of K+ ion transport in brown fat mitochondria is mediated by the action of nucleotides and fatty acid esters on the uncoupling protein and ADP/ATP antiporter.

[Effect of antibodies against mitochondrial K+-transporting protein on K+ transport in rat liver mitochondria]. / Vliianie antitel k mitokhondrial'nomu K+-transportiruiushchemu belku na transport K+ v mitokhondriiakh pecheni krysy.

The K+ transport in rat liver mitochondria was studied by the immunochemical method. Antibodies to mitochondrial K+-transporting protein with molecular weight 60 kDa were obtained and used as possible inhibitor or K+ transport. Antibodies depressed the DNP-induced K+ efflux and energy-dependent swelling by 50% without causing changes in respiration and oxidative phosphorylation.