P734: Characterizing the forces that stabilize DNA: Biophysical analysis of oligonucleotides using thermal denaturation and isothermal titration calorimetry
A series of experiments for the biophysical characterization of DNA and specific oligonucleotides (oligos) has been developed. These experiments involve thermal denaturation to determine the melting temperature, Tm, as a measure of the thermodynamic stability of the duplex. A range of conditions was employed including variations in ionic strength, variations in solvent, and the presence of intercalating agents such as ethidium bromide. Isothermal titration calorimetry (ITC) was employed to obtain a thermodynamic profile of strand association. These experiments clearly show that, while it is commonly assumed that the GC/AT ratio is of prime importance in determining Tm, the role of the base sequence and solvent conditions must be considered for an accurate assessment of the forces stabilizing the duplex structure. In addition, the oligos were modified with the anticancer compound cis-Pt(NH3)2Cl2 (cisplatin). The affect that the intra-strand Pt-GpG cross-links has on the stability of the modified oligo duplex was determined by employing the above techniques.