title: Equilibrium studies on the interaction of daunomycin with deoxypolynucleotides.
abstract: Fluorescence and absorbance methods were used to study the interaction of daunomycin with four deoxypolynucleotides. The binding may be described by the neighbor-exclusion model for binding ratios greater than 0.05, with intrinsic binding constants decreasing in the order poly[d(A-T)] X poly[d(A-T)] greater than poly[d(G-C)] X poly[d(G-C)] greater than poly(dG) X poly(dC) greater than poly(dA) X poly(dT). The exclusion parameter was found to be approximately 2 for the A-T-containing polynucleotides, 4 for the alternating G-C polymer, and nearly 10 for poly(dG) X poly(dC). Poly(dA) X poly(dT) showed positive cooperativity at low binding ratios. Thermal denaturation studies provided quantitative support for the measured binding parameters; the delta Tm values measured may be correlated primarily with the differences seen in the exclusion parameter. Sedimentation velocity experiments on daunomycin-deoxypolynucleotide complexes show an unusual nonlinear dependence of Sapp on the binding ratio for poly[d(A-T)] X poly[d(A-T)], poly[d(G-C)] X poly[d(G-C)], and poly(dA) X poly(dT), indicative of either a nonstandard conformational change accompanying intercalation or cooperative drug binding.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003630:Daunorubicin; D007700:Kinetics; D009691:Nucleic Acid Denaturation; D011089:Polydeoxyribonucleotides; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D011089:Polydeoxyribonucleotides; D003630:Daunorubicin