Study of the association between a serum albumine and a new cobalt complex

P. F. GARCIA; C. CORONEL; A. VELO; A SINGH; R. P. SHARMA; G. A. ARGÜELLO

Buenos Aires

Congreso; XL Reunion Anual de la Sociedad Argentina de Biofisica; 2011

SAB

The Photodynamic Therapy (PDT) has emerged as an attractive option for the treatment of cancer pathologies, thanks to the study and utilization of transition metal complexes (among others) as photosensitizers.Bovine Seric Albumine (BSA) is a well studied protein due to its ability to act as carrier for number of substrates to the interior of the cell. The aim of this work was to study the binding between Bovine Seric Albumine (BSA) and a new cationic cobalt(III) complex, [Co(phen)(H2biim)2]3+ synthesized by Dr. R. P. Sharma et al. The fluorescence quenching of the protein by the cationic cobalt(III) complex at different excitation wavelengths and at different temperatures has been studied. It was observed that both tryptophan as well as tyrosine residues are involved in the quenching processes, as also observed in our earlier studies. Using the Bhattacharya`s model, association constant (K) were determined which render a value around 9x10^4 at room temperature.By the study of K at different temperatures and using the Van`t Hoff equation it was possible to evaluated the thermodynamics parameters. dH=6,65kJ/mol, dS=117,3J/mol and dG= -28,3kJ/mol. In conclusion, the complex and the protein bind spontaneously and the association is an endothermic process. According to the thermodynamic parameters, the acting forces are mainly hydrophobic interactions, although the electrostatic attraction cannot be discarded.