Thermodynamic Studies on the Interaction of Phthalocyanine with Bovine serum albumin

Using UV-Vis spectrophotometric method the interaction of water soluble phthalocyanine, Cobalt(ΙΙ) 4,4′,4′′,4′′′- tetrasulfophthalocyanine(CoTSPc), with bovine serum albumin (BSA) to determine the formation constant and related thermodynamic functions. The measurements were considered in 1mM sodium phosphate buffer, pH 7.0 and at 5 different temperatures 20, 25, 30, 35 and 40ºC. The results showed that the best fitting corresponds to a 1:1 complex model between BSA and CoTSPc. The optical adsorption spectra of phthalocyanine was analyzed in order to obtain binding constants, K, using SQUAD software. By using the Van’t Hoff equation, values of enthalpy, ∆H˚,and entropy, ∆S˚,changes associated to the (BSA+ CoTSPc) were determined, and the values of ∆G˚ were calculated by using  ∆G˚ = -RTlnK at 5 different temperatures.