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B P Ulanov

Publications and source records attributed to B P Ulanov.

At least 19 recordsLinked to original sources
PubMed1989

[The Z-form of bacteriophage lambda DNA, modified in situ].

Using the methods of chemical modification, restriction analysis and immune-electron microscopy it has been shown that the definite regions of the bacteriophage lambda DNA contain unpaired bases in situ. The distribution map of such sites along the genome has been constructed. The correlation of the in situ modification and the reaction with anti-Z-DNA antibodies is shown for the 44972 bp site of bacteriophage DNA. The possibility of the existence of Z-form DNA in situ is discussed.

Bacteriophage lambda↗
PubMed1988

[Unpaired bases in the B--Z junction of the supercoiled plasmid].

The restriction analysis has been used to establish that O-beta-diethylaminoethylhydroxylamine (OHA) produces modification of unpaired cytidines in the polylinker region adjacent to the Z-insert (dG-dC)10. (dG-dC)10 in the negatively supercoiled plasmid pGC20. The length of the transition region between B- and Z-portions of DNA is not less than 36 bps. The reaction of OHA with the unpaired cytidines in the B-Z junction is a fixing one and produces no secondary despiralling of the neighboring regions. The reaction with DNA proceeds much slower than the one with monomers and single-strand polynucleotides. The structural nonuniformity has been observed, which is manifested in the alternating B and "non-B" form DNA in the B-Z junction. It is suggested that these junctions may contain nucleotide sequences which are stable to violation of the B structure during the change in superhelical density of DNA.

Base Sequence↗
PubMed1985

[Properties of the plasmid pFT15/10-1 isolated from the vaccine strain of Francisella tularensis].

Plasmid, designated pFT15/10-1, was isolated from Francisella tularensis vaccine strain 15/10. The plasmid is presented by the homogeneous 5.02 +/- 0.054 Md monomeric circular DNA molecules in electron microscopic preparations. Plasmid size is 7-7.3 kb as defined by electrophoresis in agarose gel. The restriction analysis has revealed that plasmid pFT15/10-1 possesses a single specific cleavage site for restriction endonuclease EcoRI, two sites for restriction endonucleases BamHI, BgIII, HincII, HindIII, PstI, three sites for BglI and SalI, some for AluI, TagI, MvaI, CfrI. Plasmid is not digested by restriction endonucleases SmaI, XmaI, KpnI, MluI. Restriction map of the plasmid was constructed for most frequently used restriction endonucleases.

Bacterial Vaccines↗
PubMedDate not supplied

[Double modification of cytidine residues in DNA].

The reaction of O-beta-diethylaminoethylhydroxylamine (O-beta-HA) with cytidine was studied and its mechanism was shown to be analogous to that of the reaction of hydroxylamine of O-methylhydroxylamine with cytidine. In experiments involving reaction of denatured DNA with O-beta-HA., Sephadex G-15 columns were used for the quantitative separation of normal and modified nucleosides after enzymatic hydrolysis of modified DNA by exonuclease A5 followed by alkaline phosphatase treatment. DNA cytidine residues of free cytidine with O-beta-HA. Modified cytidines can form complex with phosphotungstic acid (PTA). It was shown that one mole of PTA was bound per one mole of modified cytidine either in DNA or in free state. Electron microscopic examination of denatured DNA molecules modified by O-beta-HA and reacted with PTA revealed linear arrays of electron-scattering spots which presumably correspond to PTA molecules complexed with modified cytidine in DNA chains.

Alkaline Phosphatase↗
PubMedDate not supplied

[Nitrogen mustard fixes the Z-conformation in poly[d(G-C)]poly[d(G-C)] and DNA].

The reactions of poly(dG-dC).poly(dG-dC) and (dG-dC)10 insert in the plasmid pGC20 with N-methyl-bis(2-chloroethyl)-amine (nitrogen mustard, HN-2) have been studied. It is shown that nitrogen mustard does not induce the B----Z transition in poly(dG-dC).poly(dG-dC), but produces fixation of the polynucleotide Z-conformation once this exists. In the case of pGC20 plasmid DNA, nitrogen mustard also fixes Z-form of the (dG-dC)-insert. The rate constant of the reaction of nitrogen mustard with guanine in the polynucleotide (k = 9,0.10(-3) min-1) is about one-third of that for the fixation of Z-form of the (dG-dC)-insert in the plasmid (k1 = 2,8.10(-2) min-1) which is attributed to a greater rate of formation of diguanyl derivative in the opposite DNA chains. It is suggested that nitrogen mustard is capable of fixing the Z-form DNA not only in vitro, but also in vivo.

Circular Dichroism↗
PubMedDate not supplied

[Comparison of the state of the area between B- and Z-segments of superhelical plasmids in vitro and in situ].

The structure of B-Z junction in a cloned plasmid pGC20 containing a (dG-dC)10 insert at the SmaI site has been studied in vitro and in situ by modifying the DNA with O-beta-diethylaminoethylhydroxylamine (OHA). The latter is an analog of hydroxylamine possessing specificity with respect to unpaired cytidine. Experiments in vitro showed a complicated pattern of inhibiting the restriction hydrolysis of the OHA-modified DNA within the polylinker region of the plasmid. As the duration of the DNA reaction with OHA grows, a gradual increase in the inhibition of restriction is observed at the BamHI site neighboring the Z-insert and at the HindIII site at a distance of about 30 bp from the insert, while an intact segment (containing the SalGI site) is retained in the intermediate region. On passing to the cell level, only the region immediately adjacent to the Z-insert appears to be modified. According to estimates, about 30 to 40% of pGC20 molecules have the (dG-dC)10 insert in the Z-form when modified in situ in 1M OHA, pH 5.0.

Base Sequence↗