[The analysis of biochemical markers of MCF-7 cells apoptosis induced by recombinant analog of lactaptin].

Earlier we isolated and characterized human milk pro-apoptotic peptide - lactaptin and generated its engineered analog - RL2. It was shown that both lactaptin and RL2 are capable to induce apoptotic death of MCF-7 cells. In this report we have analyzed biochemical markers of RL2 induced MCF-7 apoptosis. The activation of initiator and effector caspases as well as mitochondrial membrane potential and cytoplasm membrane changes were analyzed using flow cytometry and Western-blot methods. We have found that RL2 induced apoptotic death of MCF-7 cells was accompanied by PS exposure on the plasma membrane surface. It also was shown that RL2 has induced dissipation of mitochondrial membrane potential and resulted in activation of initiator caspases 8, 9 and effector caspase 7.

[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 MKA 13D6 monoclonal antibody against glycoprotein of the tick-borne encephalitis (TBE) virus. This plasmid provided expression in Escherichia coli cells of the sc13D6 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 sc13D6 was (3.0 +/- 0.2) x 10(7) M(-1) for the equilibrium state and (2.8 +/- 0.3) x 10(7) 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 sc13D6 was 16.7 microg/ml.

[Localization of lysine residues in the site of initiating substrate binding of E. coli RNA-polymerase]. / Lokalizatsiia ostatkov lizina v oblasti sviazyvaniia initsiiruiushchego substrata RNK-polimerazy E. coli.

Superselective affinity labelling of E. coli RNA polymerase in a complex with the promoter-containing fragment of T7 DNA by treatment with orto-formylphenyl ester of GMP followed by addition of [alpha-33P]UTP resulted in covalent binding of the residue--pGpU (p-radioactive phosphate) with one of lysine residues of the beta-subunit, Lys1048, Lys1051, Lys1057, Lys1065. The amino acid sequence of this region of the beta-subunit of E. coli RNA polymerase has a high extent of homology with that deduced for a region of tobacco chloroplast RNA polymerase on the basis of the nucleotide sequence of the chloroplast rpoB-like gene.

[Covalent labelling of the Klenow fragment of DNA-polymerase I from E. coli]. / Kovalentnoe mechenie fragmenta Klenova DNK-polimerazy I E. coli.

Incubation of the Klenow fragment of E. coli DNA polymerase I with [alpha-32P] dNTP (or NTP) results in the covalent radiolabelling of the enzyme, the bond being stable in acid (pH 2) and alkaline (pH 12) conditions and nucleophiles, such as beta-mercaptoethylamine, efficiently inhibiting the labelling. It is suggested that radiolabelling of the enzyme is the result of formation of chemically active products of the radiolysis of [alpha-32P]NTP (which are likely to be radicals). Non-radioactive NTP hinder the labelling, whereas Mg2+ and polynucleotide do not affect it. Cleavage of the enzyme by hydroxylamine and cyanogen bromide and analysis of gel-electrophoretic patterns of the cleavage products led to conclusion that 32P-label is located between Gly-544 and Met-647.

[Template-primer-dependent inactivation of DNA polymerase alpha from human placenta by 2',3'-epoxyadenosine-5'-triphosphate]. / Matritsa-praimerzavisimaia inaktivatsiia DNK-polimerazy alpha iz platsenty cheloveka 2',3'-époksiadenozin-5'-trifosfatom.

Modification of the human placenta DNA polymerase alpha by 2',3'-epoxyadenosine 5'-triphosphate (eATP) was investigated. The latter binds to the protein both in absence and in presence of template-primer complex. However for inactivation of the enzyme, reagent-complementary template, primer and Me2(+)-ions are required. The inactivation is apparently due to the affinity modification of dNTP-binding site by eATP; covalent binding of the reagent off the enzyme's active site without affecting the DNA polymerase activity is also suggested. The enzyme inactivation by eATP and its protection from inactivation in the presence of dATP were used to determine Kd values of complexes of the enzyme with eATP (90 microM) and dATP (1 microM), the latter value being 13-times lower than Km for dATP (13 microM) in the polymerisation reaction. Using the dependence of the DNA polymerase inactivation by eATP on the primer concentration, Kd for enzyme-primer complexes were estimated. The Kd value for d(pA)10 (0.33 microM) was close to Km value (0.43 microM) for this primer. eATP was concluded to be a useful reagent for estimating the efficiency of the complex formation of different ligands with dNTP- and primer-binding sites of DNA polymerase.

[Isolation and various properties of nucleoside monophosphate kinases from Escherichia coli]. / Vydelenie i nekotorye svoistva nukleozidmonofosfatkinaz iz Escherichia coli.

A technique is proposed for isolation of nucleosidemonophosphate kinases--AMP-kinase (EC 2.7.4.11), GMP-kinase (EC 2.7.4.8), CMP-kinase (EC 2.7.4.14), UMP-kinase (EC 2.7.4.14) and TMP-kinase (EC 2.7.4.9)--from E. coli MRE-600. It involves cell destroying, precipitation of nucleic acids with polyethyleneimine, fractionation with ammonium sulphate followed by chromatography on different carriers (DEAE-Toyopearl-650 M, Matrex gel Blue A, Matrex gel Red A). The technique enables all the five enzymes to be obtained separately and without contaminations with nucleotide dephosphorylating enzymes. For all the enzymes the pH optimum was found to range from 6.5 to 8.0, and Mg2+ ions were found to be the best activator for all the enzymes studied. The substrate specificity was investigated with respect to acceptors and donors of the phosphate groups. The enzymes showed strict specificity to the heterocyclic base of the acceptor phosphate group. AMP-, GMP- and CMP-kinases phosphorylated the corresponding deoxynucleoside monophosphates less effectively than ribonucleoside monophosphates. ATP was found to be the most effective phosphate donor for all the enzymes under study.

[Interaction of oligonucleotides and ATP with preparations of sIgA possessing protein kinase activity]. / Vzaimodeistvie oligonukleotidov i ATP s preparatami sIgA, obladaiushchimi proteinkinaznoi aktivnost'iu.

Interaction of secretory immunoglobulins A of a varying degree of purity with oligonucleotides and ATP has been studied by the method of affinity modification. For this aim we used reactive derivatives of 32P-labeled deoxyoligonucleotide (ClRCH2NHp(T)14) and [gamma-32P]ATP (ClR-32PppA) or ATP (ClR-pppA) bearing a 4-[(N-2-chloroethyl-N-methyl)amino]benzylamine residue. Preparations of sIgA were obtained from human milk by sequential chromatography on protein A-sepharose (P1), DEAE-fractogel (P2) and by gel-filtration in 50 mM NaOH (P3). It was revealed, that the H- and L-chains of sIgA P1; H-, L-chains and secretory component (SC) in sIgA P2 and only SC in sIgA P3 were exposed to modification after incubation with ClRCH2NHp(T)14. LPS, DNA, tRNA, heparin, sufficiently inhibited the modification of chains of sIgA P1. These competitors did not influence the modification of H- and L-chains of sIgA P2, but DNA, tRNA, heparin, inhibited binding of SC with the modifier. Suppressing affect of binding of ClRCH2NHp(T)14 with secretory component of sIgA P3 by d(T)14 has been observed as well. The research of ClR-32PppA interaction with sIgA P3 has shown that H- and L-chains of sIgA are exposed to modification. ATP inhibited the reaction. Study of the influence of modification on the protein kinase activity of sIgA P3 has revealed, that the preliminary incubation of sIgA P3 with ClR-pppA leads to inhibition of protein kinase activity. We suggest that sIgA, possessing the protein kinase activity (sIgA-abzymes) has an ATP-binding center (catalytic center) and has an oligonucleotide-binding center as well.