The interaction between silicotungstic heteropolyacid and bovine hemoglobin (BHb) was investigated using fluorescence and UV-Vis. The experimental results show that the fluorescence quenching of BHb by silicotungstic heteropolyacid is a result of the formation of SiW-BHb complex; and the quenching mechanism is mainly static quenching. The binding site number n, apparent binding constant KA and corresponding thermodynamic parameters were measured at different temperatures. The process of binding SiW molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Electrostatic interaction plays a major role in stabilizing the complex. The effect of silicotungstic heteropolyacid on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy.
