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Behavior of topotecan, DNA topoisomerase I inhibitor, was studied in aqueous solutions by optical methods. Topotecan absorption spectra were recorded in the pH range 0.5–11.5 and its pKa were determined. Quantum chemical calculations were made for all charge states of the topotecan molecule in lactone and carboxylate form. The calculated absorption maxima(More)
When located in the DNA minor groove, dimeric bisbenzimidazoles DB(n) effectively inhibited in vitro the Dnmt3a catalytic domain (IC₅₀ 5-77 μM). The lowest IC₅₀ value was observed for compound DB(11) with an 11-unit methylene linker joining the bisbenzimidazole fragments. Increased time of incubation of DNA with DB(n) as well as the presence of AT-clusters(More)
With the goal to design ligands recognizing extended regions on dsDNA, a covalent dimer of the fluorescent dye Hoechst 33258 [bis-HT(NMe)] composed of two dye molecules linked via the phenol oxygen atoms with a (CH2)3-N+ H(CH3)-(CH2)3 fragment was constructed using computer modeling and then synthesized. Its interactions with the double-stranded DNA (dsDNA)(More)
Interaction of DNA with the analogs of the antibiotic distamycin A having different numbers of pyrrolcarboxamide groups and labeled with dansyl was studied. The binding isoterms of the analogs to synthetic polydeoxyribonucleotides were obtained. Analysis of the experimental data leads to the following conclusions: (1) the free energy of binding of the(More)
Dimeric Hoechst 33258 molecules [dimeric bisbenzimidazoles (DBBIs)] that, upon binding, occupy one turn of the B form of DNA in the narrow groove were constructed by computer simulation. Three fluorescent DBBIs were synthesized; they consist of two bisbenzimidazole units tail-to-tail linked to phenolic hydroxy groups via penta-or heptamethylene or(More)
Ten new fluorescent dyes have been tested as possible tools for human and plant chromosome banding; eight of the tested dyes were dimer derivatives of bisbenzimidazole (Hoechst 33248). The dimer compounds differed from each other by the length of the linker connecting benzimidazole moieties and by the structure of the moieties themselves. Four compounds(More)
It was found recently that Hoechst 33258, a dsDNA fluorescent dye used in cytological studies, is an efficient inhibitor of the interaction of TATA-box-binding protein with DNA, DNA topoisomerase I, and DNA helicases. In addition it proved to be a radioprotector. Biological activity of Hoechst 33258 may be associated with dsDNA complexes of not only(More)
The design and DNA binding activity of beta-structure-forming peptides and netropsin-peptide conjugates are reported. It is found that a pair of peptides-S,S'-bis(Lys-Gly-Val-Cys-Val-NH-NH-Dns)-bridged by an S-S bond binds at least 10 times more strongly to poly(dG).poly(dC) than to poly(dA).poly(dT). This peptide can also discriminate between 5'-GpG-3' and(More)