Possible Intercalation of DNA by Ruthenium(II) Pteridinyl Complexes

Shannon R. Dalton, Samantha Glazier, Sharon N. Burgmayer

Department of Chemistry, Bryn Mawr College, Bryn Mawr, PA 19010

Intercalating molecules can distort the helical shape of DNA, resulting in the inhibition of replication enzymes, and therefore have pharmaceutical applications. Due to their inherent photochemical stability, as well as redox and photophysical properties, transition metal complexes make it possible to utilize multiple techniques to study intercalation. One such complex, [Ru(phen)₂DPPZ]²⁺_, has been shown in previous work to intercalate due to its large heterocyclic ring system. Previous fluorescence and absorbance titrations give evidence that three similar ruthenium compounds, [Ru(II)(bpy)₂(phen-dimethylalloxazine)]²⁺, [Ru(II)(bpy)₂(phen-alloxazine)]²⁺_, and [Ru(II)(bpy)₂(phen-diaminopteridine)]²⁺ bind to calf thymus DNA. These studies cannot specify the mode of binding, so additional experiments are required. Reported are the results of viscosity studies which can differentiate between binding mechanisms. Future experiments include polyacrylamide gel electrophoresis to show sequence specific intercalation due to the unique hydrogen bonding properties of the pterin derivative phenanthroline ligands.