[Synthesis of 3'-mercapto-2',3'-dideoxynucleoside-5'-triphosphates and their properties in DNA synthesis with RNA-dependent DNA polymerases]. / Sintez 3'-merkapto-2',3'-didezoksinukleozid-5'-trifosfatov i ikh svoistva v sinteze DNK s RNK-zavisimymi DNK-polimerazmi.

3'-Mercapto-2',3'-dideoxy-NTP were synthesized and tested as DNA chain terminating nucleotides. It is shown that the analogues selectively and irreversibly terminate DNA chain elongation by AMV and HIV reverse transcriptases and terminal deoxynucleotidyl transferase, whereas calf thymus alpha DNA polymerase, E. coli DNA polymerase I (Klenow fragment) and MLV reverse transcriptase do not use the nucleotide analogues as chain terminator substrates.

[Hydrolysis of 5'-phosphonates and nucleoside phosphates by phosphatases of various origin and human and calf serum]. / Gidroliz 5'-fosfonatov i fosfatov nukleozidov fosfatazami razlichnogo proiskhozhdeniia i syvorotkami krovi cheloveka i telenka.

The hydrolysis of 5'-phosphonates of 2'-deoxythymidine and its 3'-modified analogs, inhibiting the HIV reproduction, by the E. coli alkaline, calf intestine and human placenta phosphatases as well as by the Crotalus atrox venom 5'-nucleotidase were studied. Transformations of 5'-phosphonates of adenosine and its analogs during incubation with human and fetal calf blood sera were investigated. The nucleotide derivatives modified at the phosphate residue were not hydrolyzed by any of the phosphatases studied except for the cobra venom 5'-nucleotidase, the effectiveness of the latter depended on the substitutes at both phosphate and sugar residues. 2'-Deoxyadenosine incubation with blood sera resulted in its transformation to 2'-deoxyinosine and then to hypoxanthine. 2'-Deoxyadenosine 5'-phosphonates were stable during incubation with blood sera under the same conditions.

[3'-Mercapto-3'-deoxythymidine-5'-triphosphate as a terminator of DNA synthesis catalyzed by RNA-dependent DNA-polymerases]. / 3'-Merkapto-3'-dezoksitimidin-5'-trifosfat kak terminator sinteza DNK, kataliziruemogo RNK-zavisimymi DNK-polimerazami.

3'-Mercapto-3'-deoxy-TTP was synthesized and tested as DNA chain terminator nucleotide for calf thymus alpha DNA polymerase, E. coli DNA polymerase I (Klenow fragment), terminal deoxyribonucleotidyltransferase (Bollum enzyme) and reverse transcriptase from AMV- and HIV-I-viruses. It was shown that the compound terminates DNA chain elongation by reverse transcriptases selectively and irreversibly. Other tested DNA polymerases do not use this nucleotide analogue as a substrate. 3'-Mercapto-3'-deoxythymidine was tested on lymphoblastoid T-cell line MT-4 with HIV-viruses and shown to suppress viruses as efficiently as 3'-azido-3'-deoxythymidine.

[A new reaction catalyzed by Bollum's terminal deoxyribonucleotidyltransferase]. / Novaia reaktsiia, kataliziruemaia terminal'noi dezoksiribonukleotidiltransferazoi bolluma.

The highly purified preparations of Bollum's terminal transferase from calf thymus were shown to catalyze, along with the common reaction of nucleotide addition to the 3'-terminus of an oligonucleotide primer, a "non-common" reaction between dNTP or rNTP on one hand, and various alcohols on the other hand. This reaction was carried out with ethylene glycol, glycerol, ethanol and methanol to produce substances containing one molecule of nucleotide, one molecule of alcohol and non-organic pyrophosphate. The reaction conditions are cacodylate buffer, pH 7, 2, in the presence of Mg2+ or Co2+ ions. The structure was determined for the product of the reaction between glycerol and dATP, which appeared to be 2,3-dihydroxypropyl-ether of 2'-deoxyadenosine-5'-monophosphate.

[Conformation limited nucleoside-5'-phosphates as termination substrates for DNA-polymerases]. / Konformatsionno ogranichennye nukleozid-5'-trifosfaty kak terminatornye substraty DNK-polimeraz.

We have investigated the ability of some nucleoside 5'-triphosphate analogues to terminate the DNA synthesis catalyzed by calf thymus DNA polymerase alpha and terminal deoxynucleotidyl transferase, rat liver DNA polymerase beta, E. coli DNA polymerase I (Klenow's fragment) and AMV reverse transcriptase. It has been shown that lyxoanhydronucleoside 5'-triphosphates terminate DNA synthesis catalyzed by reverse transcriptase and terminal deoxynucleotydil transferase. 2',3'-O-Isopropylidenecytidine 5'-triphosphate inhibits the DNA synthesis catalyzed by reverse transcriptase and DNA polymerase beta and its moiety was incorporated in the place of dTMP residue. Riboanhydroadenosine 5'-triphosphate reveals the properties of an effective termination substrate for all the DNA polymerases studied. This is the first attempt to investigate nucleotide analogues with the restricted conformation of the carbohydrate moiety as termination substrates for several prokaryotic and eukaryotic DNA polymerases.

[Synthesis of 2',3',-dideoxy-3'-fluoradenosine and -guanosine, their 5'-triphosphates and a study of 2',3'-dideoxy-3'-fluoronucleoside- 5'-triphosphates as substrates for DNA-polymerases]. / Sintez 2',3'-didezoksi-3'-ftoradenozina i -guanozina, ikh 5'- trifosfatov i izuchenie 2',3'-didezoksi-3'-ftornukleozid-5'-trifosfato v kachestve substratov DNK-polimeraz.

Potential antiviral and antitumour nucleosides, 3'-fluoro-2', 3'-dideoxy-adenosine and -guanosine, have been synthesized by the chemical transglycosylation reaction using 5'-O-acetyl-3'-fluoro-2', 3'-dideoxy-thymidine and -uridine as donors of the carbohydrate fragment and persilylated 6-N-benzoyladenine and 2-N-palmitoylguanine as acceptors, respectively. 5'-Triphosphates of 3'-fluoro-2', 3'-dideoxy-thymidine, -cytidine, -adenosine, and -guanosine (dNTP(3'F] were synthesized and tested as terminators in cell-free system of DNA synthesis catalyzed by RNA-directed DNA polymerase (reverse transcriptase, RT) from the avian myeloblastosis virus (AMV) and E. coli DNA polymerase I (Klenow fragment). A method of estimating relative effectiveness of dNTP(3'F) incorporation into DNA growing chain in comparison with the natural substrates was developed. It is shown that, in case of AMV-RT, dATP(3'F), dCTP(3'F) incorporate 14 times less efficiently than dATP and dCTP respectively, and dTTP(3'F) 3 times less effectively than the corresponding natural substrates, whereas dGTP (3'F) is as efficient as dGTP. With E. coli DNA polymerase I (Klenow fragment) dATP (3'F) and dCTP(3'F) are ca. 100 times less efficient, and dTTP(3'F) and dGTP(3'F) are ca. 50 times less efficient than the respective natural substrates.

[DNA polymerase I, Klenow fragment of Escherichia coli: hydrolysis and pyrophosphorolysis of DNA containing phosphothioate groups]. / DNK-polimeraza I Escherichia coli, fragment Klenova: gidroliz i pirofosforoliz DNK, soderzhashchei fosfotioatnye gruppy.

Reaction of DNA synthesis catalyzed by DNA polymerase I KF in the presence of 2'-deoxynucleoside 5'-alpha-thiotriphosphates (dNTP alpha S) was investigated. DNA with thiophosphate groups (DNA[P=S]) obtained by such a way was studied in reactions of hydrolysis and pyrophosphorolysis catalyzed by DNA polymerase I KF. It is shown that the rate of DNA elongation is decreased both on the step of incorporation of dNMP alpha S residues and on the step of incorporation of the next dNMP residue. The rate of pyrophosphorolysis of 3'-terminal dNMP alpha S was demonstrated to be one order of magnitude less in comparison with the corresponding reaction with the natural dNMP residue. Contrary, the rate of 3'----5'-exonuclease hydrolysis of both DNA[P=S] and DNA of the same structure revealed no distinguishable differences.

[Analogs of deoxyribonucleoside-5'-triphosphates modified in the base and sugar moieties: substrate properties in DNA biosynthesis in cell-free systems]. / Analogi dezoksiribonukleozid-5'-trifosfatov, modifitsirovannye po osnovaniiu i sakharnomu ostatku: substratnye svoistva pri biosinteze DNK v beskletochnykh sistemakh.

Incorporation of 2'-deoxyribonucleotide 5'-triphosphate derivatives, chemically modified both in the base and at 3'-position, into DNA by four different DNA polymerases was investigated. It is shown that 3'-azido- and 3'-amino-2',3'-dideoxy-(E)-5-(2-bromovinyl)-uridine 5'-triphosphates effectively terminate DNA synthesis catalyzed by E. coli DNA polymerase I, rat liver DNA polymerase beta, and AMV reverse transcriptase. Calf thymus DNA polymerase alpha incorporates only the 3'-amino derivative. DNA polymerases I and beta catalyse DNA synthesis in the presence of beta-D-(2'-deoxyribofuranosyl)-1-benzimidazol 5'-triphosphate, inserting the corresponding monophosphate in place of -dGTP, whereas 3'-substituted analogues of this compound were inactive in the reactions.

[Ability of 3'-substituted nucleoside phosphothioates to terminate DNA synthesis catalyzed by various DNA-polymerases]. / Sposobnost' 3'-zameshchennykh fosfotioatov nukleotidov terminirovat' sintez DNK, kataliziruemyi raznymi DNK-polimerazami.

Ability of some new substrates containing the 5'-alpha-thiotriphosphate residue to terminate the DNA synthesis catalyzed by several DNA polymerases has been investigated. The cell-free test system contained the M13mp10 phage single-stranded DNA and a synthetic oligonucleotide primer. Reverse transcriptase from avian myeloblastosis virus catalyzed termination of DNA synthesis by 3'-azido-3'-fluoro- and 3'-amino-2',3'-dideoxythymidine-5'-(alpha-thio)triphosphates, whereas rat liver DNA polymerase beta and E. coli DNA polymerase I (Klenow's fragment) utilized only the second and the third compounds, and calf thymus DNA polymerase alpha failed to utilize any of the substrates. Low specificity of reverse transcriptase to different moieties of the substrate molecules is discussed.

[Substrate inhibitors of DNA biosynthesis]. / Substratnye ingibitory biosinteza DNK.

We present an account of the data on the inhibition analysis of DNA biosynthesis by substrate analogs with DNA polymerases of different origin. An attempt has been made to substantiate the factors that underline the specificity of inhibitors with respect to DNA synthesis that is catalyzed by various DNA polymerases.

[Non-canonical nucleotide exchange catalyzed by Escherichia coli DNA-polymerase I and the two-center model of the mechanism of action of this enzyme]. / Nekanonicheskii nukleotidnyi obmen, kataliziruemyi DNK-polimerazoiEscherichia coli, i dvukhtsentrovaia model' mekhanizma deistviia éto fermenta.

It is shown, that DNA hydrolysis catalyzed by E. coli DNA polymerase I is inhibited, when a reaction mixture contains one type of deoxynucleoside 5'-triphosphate (dNTP). When the reaction mixture contains [32P]dNTP, then [32P] is incorporated into DNA and v. v. (32P) from DNA is transferred into dNTP. The nucleotide exchange between DNA and dNTP in the assay mixture is observed only in the case, when the chemical nature of nucleotide residue of dNTP and that of the 3'-terminus of DNA is the same. Analysis of products of DNA hydrolysis in the presence of one type of dNTP using electrophoresis in polyacrylamide gel shows that most of the DNA molecules are terminated at the 3'-termini by the dNMP residue of the same chemical nature as the dNTP in the assay mixture. However, in some cases DNA molecules contain one additional nucleotide residue. This phenomenon can be explained by incorporation of one additional dNMP residue originating from dNTP only in those cases, when a non-typical base pairing of this nucleotide residue with a template residue readily takes place. The above-mentioned facts can be interpreted within the model for DNA hydrolysis with involvement of two intermediate covalent forms of dNMP residues with DNA polymerase I; one dNMP-intermediate should be placed at the elongation center and the other--at the hydrolysis center. The DNA hydrolysis by 3'----5' exonuclease activity of DNA polymerase I proceeds through these two covalent forms. DNA polymerases alpha from calf thymus and T4 phage do not catalyze the nucleotide exchange between DNA and dNTP from the reaction media.

[Relationship between the molecular structure of aqueous solutions of polyethylene glycol and the compactness of double-stranded DNA molecules]. / O sviazi mezhdu molekuliarnym stroenii vodnykh rastvorov poliétilenglikolia i kompaktizatsiei dvukhtsepochechnykh molekul DNK.

The dependence of viscosity of the water solutions of poly(ethylene glycol) (PEG) on the molecular weight has been studied. It has been shown that there is a "transitional" region in PEG properties which accounts for the formation of fluctuation polymer network of the PEG molecules. It has been shown that the "transitional" region in properties of PEG which appears at a certain concentration of PEG (CtrPEG) is characteristic of the PEG preparations with molecular weights exceeding 600 and dependence of the value of CtrPEG on the molecular weight of PEG was obtained. Compactization of double-stranded DNA molecules in PEG-containing water-salt solutions has been studied and the dependence of the value of CcrPEG, . i.e. the concentration of PEG at which the compact particles of DNA appear in the solution, on the molecular weight of PEG was obtained. The correlation between these two dependences reflecting quite different physico-chemical processes shows that the double-stranded DNA molecules are constrained within the polymer network of the PEG molecules. The influence of ionic strength and ionic composition of the solution on the formation of a compact form was investigated. The transition of the DNA molecules from a linear to a compact state may occur only at a definite value of ionic strength of the solution. This transition may occur at the change of K+ for Na+ cations (at a constant value of CPEG). The extent of compactization of the DNA molecules in PEG-containing water-salt solutions is monitored by the molecular structure and by the ionic strength of the solvent. It is supposed that the peculiarities of compactization of the DNA molecules in PEG-containing water-salt solutions reflect some characteristics of conformational transitions of the DNA molecules which occur in vivo.