Association Studies Between a Complex of Re(I) and Biopolymers

F. RAGONE; H. MARTINEZ; P. F. GARCIA; J. YAÑUK; G. A. ARGÜELLO; G. RUIZ; F. CABRERIZO; E. WOLCAN

Córdoba Capital

Conferencia; 16th International Conference of Photobiology; 2014

The spectroscopy, photochemistry and photophysics of Re(I) carbonyl?diimine complexes fac-ReX(CO)3(-diimine) continue to attract much research interest ever since their intriguing excited stateproperties were first recognized in the mid-1970s [1].There are potential biochemical and technical applications based on the formation of adducts betweentransition metal complexes of Re(I), and biological macromolecules such as DNA as many of thosecomplexes have the capacity to cause DNA damage by photoinduced oxidative strand breakage [2]. Theuse of transport proteins to achieve a specific accumulation of drugs in tumor cells seems to be an area ofkeen interest [3]. Therefore, many researchers endeavors sought to identify and characterize theassociation of rhenium complexes to transport proteins BSA and HSA (Bovine and Human SerumAlbumin), to determine the potential application of these complexes in the delivery of drugs [4].In previous work, we have synthesized and characterized a new water soluble complex,Re(CO)3(pterin)(H2O) (pterin = 2-amine-4-pteridinone).5 In this work we study the interaction betweenReI(CO)3(pterin)(H2O) and calf thymus DNA, bacterial plasmids and synthetic polynucleotides (poly-[dCdG]2 and poly-[dAdT]2) as well as transport proteins (BSA and HSA). The type interaction betweenthe Re(I) complex and the polynucleotides was ascertained through the effect exerted by increasing thepolynucleotide concentration over the luminescence properties (quantum yields and lifetime) ofReI(CO)3(pterin)(H2O) solutions. Moreover, the effect on the conformation and the level of supercoilingthat occurs by the interaction of ReI(CO)3(pterin)(H2O) with the plasmid DNA was studied byelectrophoresis gel and atomic force microscopy (AFM).Thermodynamic parameters (H, G and S) and the association constant (Kb) which characterize theinteraction of the complex with transport proteins such as HSA and BSA were determined by measuringthe quenching of the protein fluorescence in the presence of different complex concentrations.Additionally, circular dichroism experiments helped to identify the binding site for the complex andconformational changes experienced by the protein due to the interaction.