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Densities, ρ, kinematic viscosities, ν, and refractive indices, n D, were determined for poly(ethylene glycol) 200 and 400 + 1,3-dioxolane, + 1,4-dioxane, + oxolane (tetrahydrofuran, THF), and + oxane (tetrahydropyran, THP) binary mixtures over the entire range of composition at 303.15 K and at atmospheric pressure. The excess molar volumes, , deviations in viscosities, Δη, and deviations in molar refractions, ΔR, calculated from experimental measurements, are always negative. The results were correlated with the Redlich−Kister polynomial. The McAllister multibody interaction model was used to correlate the kinematic viscosities of liquid mixtures with mole fractions. The viscosity dependence on temperature was investigated between 297.15 and 309.15 K for some solutions in a restricted composition range.

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

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The interaction of enantiomeric ketoprofen (KP) with BSA and HSA was studied by isothermal titration calorimetry (ITC). Affinity constants and thermodynamic parameters for complexation in two main protein sites were determined. Affinity constants for both proteins are generally lower for S(+)- than for R(-)-KP. Large enthalpic contributions to Gibbs free energy are compensated by large negative entropic terms for S(+) in the BSA-subdomain IIIA and HSA-subdomain IIA. The lowest energy BSA complexes of both enantiomers were structurally characterized by combining molecular mechanics (MM) and molecular dynamics (MD) with circular dichroism (CD). Comparison of quantum mechanically calculated rotational strengths with the CD signals of the complexes supported the structures. These allowed to identify the main interactions of the KP enantiomers with surrounding amino acids at short distances, that limit significantly KP mobility in both sites. In the primary binding site S(+) is close to Tyr 409 in subdomain IIIA (Sudlow site II), and R(-) is close to Trp 212 and His 240 in subdomain IIA (Sudlow site I). The same sites are involved in the formation of 2:1 complexes. The equilibrium structures are characterized by marked geometrical distortion of KP.

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