Interaction of Antitumor Agent Mitoxantrone with Double Helical Synthetic Polyribonucleotides Poly(G)⋅Poly(C) and Poly(I)⋅Poly(C)

The interaction of antitumor drug mitoxantrone (MTX) with double-stranded synthetic RNA homopolymers has been studied by means of spectroscopic (UV-Visible absorption, circular dichroism) techniques. The results show a base specificity in this interaction: the association constant with poly(G)[Formula: see text]poly(C) is higher than with poly(I)[Formula: see text]poly(C).Values of changes of the system enthalpy and entropy due to complex-formation were determined through the temperature dependence of the binding constant. Calculations show that due to the intercalation interaction of MTX, the values of changes of the system entropy and enthalpy differ from those obtained at ehtidium bromide interaction with synthetic polyribonucleotides, which shows that the intercalation interaction of MTX with double-stranded RNA significantly differs from that of ethidium bromide with RNA.

Study of Methyl Orange-Cetyltrimethyl Ammonium Bromide Interaction by Conductivity Method in Methanol-Water Mixed Solvent Media

The interaction of an anionic dye (Methyl Orange) with cationic surfactant (Cetyltrimethylammonium Bromide, CTAB) in the series of solvent containing variable compositions of methanol-water mixture (10%, 20%, 30% and 40%) was studied at room temperature (31±2oC). Conductivity measurements were done for the investigation of interaction of dyes. The specific conductance of 6.58x10-5 M to 59.22x10-5M surfactant (CTAB) and these surfactants with 1.008x10-3M dye (MO) mixtures were noted at room temperature. A theoretical model was used to calculate conductance ratio from the data of measured specific conductance values. Values of conductance ratio of CTAB-MO mixtures were found to be all less than 1 which indicated that CTAB-MO dye -surfactant mixture exert significant influence on the degree of interaction.Int. J. Appl. Sci. Biotechnol. Vol 5(2): 172-179

Ethidium Bromide Interaction with Poly(G)

In current work we investigate the interaction between polyguanylic acid and Ethidium Bromide ( EtBr ) and the changes of thermodynamic parameters due to those interactions by spectrophotometric methods. From the binding isotherms, binding constants were calculated for three different temperatures and the changes of Gibbs free energy, entropy and enthalpy for complex-formation were determined. Complex-formation with four-stranded poly(G) structure needs less conformational changes in contrast with poly(G)poly(C), and due to that, EtBr binds with 5 and not 4 nucleotides. Obtained results confirm the concept that polyguanylic acids may form four-stranded complex structures with intercalating ligand EtBr in the aqueous solution.