Study on the interaction between BSA and tetraphenyl-porphyrin derivatives

The interaction of bovine serum albumin (BSA) with tetraphenyl-porphyrin derivatives such as BrTPP and CH₃OTPP was investigated by fluorescence spectroscopy. The influence of electron effect of substituting group on fluorescence quenching mechanisms was discussed. The number of binding sites n, and the binding constant K_A and thermodynamic function were obtained. The effect of porphyrin on the conformation of BSA was analyzed by using synchronous fluorescence spectroscopy. The experimental results showed that the fluorescence intensity of BSA was quenched when the porphyrin was added. The mechanism of quenching belongs to static quenching and the binding constants between BrTPP and BSA are K_A= 2.219×10⁵ L·mol^-1 (15°C), 0.926×10⁵ L·mol^-1 (20°C), and those between CH₃OTPP and BSA are K_A=3.19×10⁴ L·mol^-1 (15°C), 2.67×10⁴ L·mol^-1(20°C), respectively.