Characterization of the interaction between Fe(III)-2,9,16,23-tetracarboxyphthalocyanine and blood proteins

The features of FeTCPc (Fe(III)-2,9,16,23-tetracarboxyphthalocyanine) binding to bovine serum albumin and bovine hemoglobin were investigated by fluorescence and UV/vis absorption spectroscopy. FeTCPc has the ability to quench the intrinsic fluorescence of both bovine serum albumin and bovine hemoglobin through mainly static quenching. The binding site number n, apparent binding constant KA and the corresponding thermodynamic parameters ΔG0, ΔH0, ΔS0 at different temperatures were calculated; both electrostatic and hydrophobic interactions play a major role in stabilizing the complex. The distance r between the donor (bovine serum albumin or bovine hemoglobin) and acceptor (FeTCPc) was obtained according to fluorescence resonance energy transfer. The effect of FeTCPc on the conformation of the two donors was analyzed using synchronous fluorescence spectroscopy.