Molecular interaction between phosphomolybdate acid and bovine hemoglobin

The interaction between bovine hemoglobin (BHb) and phosphomolybdate acid (PMo12) was investigated by UV/vis absorption, IR, circular dichroism (CD), fluorescence, resonance light scattering spectra, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. PMo12 effectively quenched the intrinsic fluorescence of BHb via static quenching. The process of binding PMo12 on BHb was a spontaneous molecular interaction procedure. The thermodynamic parameters, ΔH° and ΔS° were estimated to be 28.69 K J mol−1, 158.20 J mol−1 K−1 according to the van' Hoff equation. This indicates that hydrophobic interaction played a major role in stabilizing the PMo12-BHb complex. The effect of PMo12 on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy, IR and CD spectra.