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In this work, we conducted a study of the interaction between DNA and favipiravir (FAV). This chemotherapeutic compound is an antiviral drug for the treatment of COVID-19 and other infections caused by RNA viruses. This paper examines the electroanalytical characteristics of FAV. The determined concentrations correspond to therapeutically significant ones in the range of 50-500 µM (R2 = 0.943). We have shown that FAV can be electro-oxidized around the potential of +0.96 V ÷ +0.98 V (vs. Ag/AgCl). A mechanism for electrochemical oxidation of FAV was proposed. The effect of the drug on DNA was recorded as changes in the intensity of electrochemical oxidation of heterocyclic nucleobases (guanine, adenine and thymine) using screen-printed graphite electrodes modified with single-walled carbon nanotubes and titanium oxide nanoparticles. In this work, the binding constants (Kb) of FAV/dsDNA complexes for guanine, adenine and thymine were calculated. The values of the DNA-mediated electrochemical decline coefficient were calculated as the ratio of the intensity of signals for the electrochemical oxidation of guanine, adenine and thymine in the presence of FAV to the intensity of signals for the electro-oxidation of these bases without drug (S, %). Based on the analysis of electrochemical parameters, values of binding constants and spectral data, intercalation was proposed as the principal mechanism of the antiviral drug FAV interaction with DNA. The interaction with calf thymus DNA also confirmed the intercalation mechanism. However, an additional mode of interaction, such as a damage effect together with electrostatic interactions, was revealed in a prolonged exposure of DNA to FAV.

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Polystyrene-based support Bio-Beads® SM-2 was employed for desalting peptide-p-nitroanilides from Oxone®. Neither tosyl, 9-fluorenyl(methoxycarbonyl), p-nitroanilide groups nor indolyl or p-hydroxyphenyl side-chains of Trp and Tyr ensured an efficient adsorption of peptide-p-nitroanilides onto Bio-Beads® SM-2. Only unsubstituted phenyl-containing protection groups (carbobenzoxy or benzoyl) and Phe residues provided the adsorption of peptides on Bio-Beads® SM-2 and their efficient desalting. This support is well suitable for multiple parallel phenyl group-containing peptide derivative separations and high-throughput screenings.

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The glutarylation of lysine residues in proteins attracts attention as a possible mechanism of metabolic regulation, perturbed in pathologies. The visualization of protein glutarylation by antibodies specific to ε-glutaryl-lysine residues may be particularly useful to reveal pathogenic mutations in the relevant enzymes. We purified such antibodies from the rabbit antiserum, obtained after sequential immunization with two artificially glutarylated proteins, using affinity chromatography on ε-glutaryl-lysine-containing sorbents. Employing these anti(ε-glutaryl-lysine)-antibodies for the immunoblotting analysis of rat tissues and mitochondria has demonstrated the sample-specific patterns of protein glutarylation. The study of the protein glutarylation in rat tissue homogenates revealed a time-dependent fragmentation of glutarylated proteins in these preparations. The process may complicate the investigation of potential changes in the acylation level of specific protein bands when studying time-dependent effects of the acylation regulators. In the rat brain, the protein glutarylation, succinylation and acetylation patterns obtained upon the immunoblotting of the same sample with the corresponding antibodies are shown to differ. Specific combinations of molecular masses of major protein bands in the different acylation patterns confirm the selectivity of the anti(ε-glutaryl-lysine)-antibodies obtained in this work. Hence, our affinity-purified anti(ε-glutaryllysine)-antibodies provide an effective tool to characterize protein glutarylation, revealing its specific pattern, compared to acetylation and succinylation, in complex protein mixtures.

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The time dependence of a charge accumulation in a 10-15 M albumin solution, flowing through a measuring cell of an analytical flow system injector, had a nonlinear character under certain conditions, within a human physiological temperature range. Sharp charge increases depended on albumin concentration. This effect must be taken into consideration when generating models that describe electrokinetic phenomena in flowing protein solutions and when developing analytical flow systems for the registration of biomolecules in low concentration ranges.

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Unified schedule for multiple parallel solid-phase synthesis of so-called "difficult" peptides on polypropylene pins was developed. Increase in the efficiency of 9-fluorenyl(methoxycarbonyl) N-terminal amino-protecting group removal was shown to have a greater influence on the accuracy of the "difficult" peptide synthesis than the use of more efficient amino acid coupling reagents such as aminium salts. Hence the unified schedule for multiple parallel solid-phase synthesis of "difficult" peptides included the procedure for N-terminal amino group deprotection modified by applying a more efficient reagent for the deprotection and the standard procedure of amino acid coupling by carbodiimide method with an additional coupling using aminium salts, if necessary. Amino acid coupling with the help of carbodiimide allows to follow the completeness of the coupling via the bromophenol blue indication, thus providing the accuracy of the synthesis and preventing an overexpenditure of expensive reagents. About 100 biotinylated hepatitis C virus envelope protein fragments, most of which represented "difficult" peptides, were successfully obtained by synthesis on pins with the help of the developed unified schedule.

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Somatic angiotensin converting enzyme (sACE), contains in its single chain two homologous domains (called N- and C-domains), each bearing a functional zinc-dependent active site. The present study aims to define the differences between two sACE domains and to localize experimentally revealed antigenic determinants (B-epitopes) in the recently determined three-dimensional structure of testicular tACE. The predicted linear antigenic determinants of human sACE were determined by peptide scanning ("PEPSCAN") approach. Essential difference was demonstrated between locations of the epitopes in the N- and C-domains. Comparison of arrangement of epitopes in the human domains with the corresponding sequences of some mammalian sACEs enabled to classify the revealed antigenic determinants as variable or conserved areas. The location of antigenic determinants with respect to various structural elements and to functionally important sites of the human sACE C-domain was estimated. The majority of antigenic sites of the C-domain were located at the irregular elements and at the boundaries of secondary structure elements. The data show structural differences between the sACE domains. The experimentally revealed antigenic determinants were in agreement with the recently determined crystal tACE structure. New potential applications are open to successfully produce mono-specific and group-specific antipeptide antibodies.

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Hepatitis C virus (HCV) represents serious threat for human health due to a very high probability for developing chronic liver diseases. The virus has a number peculiarities, which helps him to escape elimination by neutralizing antibodies and immune cells. The main of them are high frequency of the amino acid substitutions within certain immunogenic parts of the viral proteins, the quasispecies nature of the virus, specific functions of the viral proteins, directed against antiviral effects. During acute phase of hepatitis C patients usually have expressed humoral and cellular responses. But only 15% of them have resolved infection. Unfavourable prognostic indications were considered to be high titers of antibodies against NS3 and NS5 proteins, low levels of Th and CTL cell responses, and probably low level of serum 2',5'- oligoadenylate synthetase at the end of acute phase of hepatitis C. Recently it has been shown the existence and significance on E2 protein NOB epitopes, antibodies to which neutralize the virus binding to cells. A lot of CTL- and Th-epitopes were mapped on the viral antigens. Efficiency of humoral and cellular immune response during chronic hepatitis C is limited. Persisting HCV infection may lead to development B-cell lymphoproliferative disorders such a mixed cryoglobulinemia, non-Hodgkin's lymphoma, and to appearence organ-specific and non-organ-specific autoantibodies.