Complexes of the antitumoral drugs Doxorubicin and Sabarubicin with telomeric G-quadruplex in basket conformation: ground and excited state properties.

摘要: We studied the binding of two anthracycline drugs, Doxorubicin and Sabarubicin, to a model telomeric sequence 5′-d[GGG(TTAGGG)3]-3′ (21-mer), assuming basket G-quadruplex (G4) conformation in Na+-rich aqueous solution. used an approach that combines spectroscopic microcalorimetric techniques obtain information about ground excited state properties most stable complexes. Both drugs bind 21-mer complexes 1 : 1 2 : 1 drug : stoichiometry coexist Binding constants were determined from fluorescence isothermal titration calorimetry experiments. For both association is driven by enthalpy disfavoured entropy case sequential events different sites. The completely quenched complex, likely electron transfer guanine system anthraquinone moiety, while part emission survives complex. Circular dichroism (CD) individual dominated signal UV near-UV Vis region. experimental CD spectra combined with conformational calculations at MM level quantum mechanical calculation rotational strength electronic transitions afforded on geometries.