Spectroscopy studies on the thermodynamic interaction of the Human Serum Albumin binding of Phthalocyanine

The thermodynamic of the binding of nickel (II) tetrasulfonated phthalocyanine anion [Ni (tspc)4-], to human serum albumin (HSA) was investigated in 5mM aqueous phosphate buffer of pH 7.40 at 25˚C using optical absorption spectroscopy. The binding constant (K) was obtained by analysis of optical absorption spectra of mentioned complex at various HSA concentrations using SQUAD software. The value of K was estimated to be 4.89´105 ± 0.03 (M-1 ) at 25°C. The thermodynamic parameters were calculated by van’t Hoff equation. The enthalpy and entropy changes were 28.08 kJmol-1 and 203.09 Jmol-1.K-1 at 25˚C, respectively. The results indicate that the binding is mainly entropy driven and the enthalpy is unfavorable for it, the hydrophobic forces thus playing a major role in the binding process.

Keywords:

Human serum albumin , Nickel (II) tetrasulfonated phthalocyanine , Thermodynamic of binding , Optical absorption