title: Equilibria and kinetics of the intercalation of Pt-proflavine and proflavine into calf thymus DNA.
abstract: The interaction of the cis-platinum derivative of proflavine [[PtCl(tmen)(2)][HNC(13)H(7)(NHCH(2)CH(2))(2)]](+) (PRPt) with CT-DNA is investigated by spectrophotometry and T-jump relaxation in 0.11M NaCl, pH 7.0, and 25 degrees C. The DNA-proflavine (PR) system is investigated under the same conditions. Static measurements indicate that base-dye interactions prevail and their analysis reveals that the site size for PRPt (n=2.6) is twice that found for PR (n=1.3). One relaxation effect is observed for the DNA/PR system and two effects for the DNA/PRPt system, the faster of them being similar to that of DNA/PR. The kinetics of the process are discussed in terms of the three-step sequence D+S <= => DS(I) <= => DS(II) <= => DS(III), where PR and the aromatic residues of PRPt intercalate into DNA by the same mechanism. The third step represents the penetration of platinum residues between base-pairs and is associated to remarkable enthalpy and entropy changes. Further mechanistic details are discussed.
mesh_terms: D000818:Animals; D020029:Base Pairing; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D007700:Kinetics; D011370:Proflavine / Q000737:chemistry*; D013950:Thymus Gland / Q000737:chemistry*
chemical_list: D004247:DNA; D011370:Proflavine