Effects of solute conditions on the relative affinities of the oligonucleotides d(G-C)5 and d(A-T)5 for the anthracycline drug 2-fluoro-4-demethoxydaunomycin.

19F NMR has been used to show that changes in NaCl concentration, as well as the presence of lysine or arginine, affect the equilibrium distribution of the synthetic anthracycline 2-fluoro-4-demethoxydaunomycin (2FD) between binding sites on d(G-C)5 and d(A-T)5 in a 1:1:1 molar aqueous system: 2FD/d(G-C)5/d(A-T)5. Varying the pH between 6.2 and 7.7 had no effect. NaCl concentrations below 0.1 M led to a d(G-C)5 preference while above 0.1 M a preference for d(A-T)5 was observed. At comparable solute concentrations, use of either lysine or arginine resulted in a significant drug preference for d(G-C)5 compared to systems containing only NaCl.