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Dializa równowagowa. Metoda badania selektywności oddziaływań ligand.DNA

Czerwińska I., Głuszyńska A., Juskowiak B.

Wiadomości Chemiczne

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2010

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[Z] 64, 1-2

105-122

EN

Equilibrium or competition dialysis is a powerful tool for binding study of ligands that are expected to bind to nucleic acids with selectivity related to their structure or sequence. In the equilibrium dialysis experiment, a set of nucleic acid samples that differ in structure and sequence is dialyzed against a test ligand solution. After equilibration, the concentration of ligand bound to each structure or sequence is determined by UV-Vis absorption or fluorescence spectroscopy in each dialysis unit. Since all nucleic acid samples are in equilibrium with the same free ligand concentration, the amount of bound ligand is directly related to the ligand binding affinity. Thus, equilibrium provides a direct measure of selectivity and identifies the nucleic acid sample, which is preferred by a particular ligand. We describe here the principles and practice of the method. Examples of an application of the method are limited to the discovery of small molecules that selectively recognize the unique structural features of G-quadruplexes. There are proofs for important functional roles of G-quadruplex structures in biology (maintenance of telomeres, transcriptional regulation, and modulation of mRNA translation). G-quadruplex DNA can exist in a variety of structural forms that may possess numerous potential binding sites for small molecules. Therefore equilibrium dialysis provides a useful tool for discovery of new mall-molecule therapeutic agents targeting G-quadruplexes.

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Interactions of the Oxidation Products of Papaverine with Guanine Quadruplexes

Mądry L., Gałęzowska E., Głuszyńska A., Hermann T., Zabel M., Juskowiak B.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 6

921-929

EN

The interactions of G-quadruplex DNA with two oxidation products of papaverine, 6a,12a-diazadibenzo-[a,g]fluorenylium derivative (1) and 2,3,9,10-tetramethoxy-12- oxo-12H-indolo[2,1-a]isoquinolinium cation (2) were investigated. Effect of the organic modifier (EtOH) and NaCl on the spectral properties and aggregation of free ligands and on the DNA-binding affinity were assessed. Ligand 1 exhibited tendency for aggregation and showed higher binding selectivity for G-quadruplex DNA over double-stranded DNA. Both ligands were capable of interacting with DNA according to three binding modes: (i) electrostatic interactions, (ii) classical intercalation to dsDNA, and (iii) the specific binding to quadruplex DNA. The cytotoxic activity of ligand 2 was generally higher than that for ligand 1, approaching a micromolar concentration level that may suggest its telomerase inhibition activity.

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Enantioselective Oxidation of Metghyl p-Totyl Sulfide Catalyz4ed by Chiral Schiff Base-Vanadium Complexes

Głuszyńska A., Krajewska K., Rozwadowska M. D.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 11

1703-1710

EN

Oxidation of methyl p-tolyl sulfide with hydrogen peroxide catalyzed by VO(acac)2 - Schiff base 12 complex afforded R-(+)-methyl p-tolyl sulfoxide in high yield and with 43% e.e. Recrystallization of the product from ethyl ether/hexane resulted in the sulfoxide enantiomerically enriched up to 99.7% [m.p. 71-74_C; [_]D +144.6_ (c = 2.02, acetone)].