Fluorescence quenching study on the interaction between quercetin and lipoxygenase

The interaction between quercetin and lipoxygenase was investigated by fluorescence spectroscopy. The analysis of the emission quenching at different temperatures revealed that the quenching mechanism correspond to a static process and, as consequence, a complex quercetin-lipoxygenase is formed. The thermodynamic parameters ΔG, ΔH and ΔS were calculated to be-32.57 kJ mol(-1),-3.21 kJ mol(-1) and 87.14 J mol(-1) K(-1) respectively, which suggest that hydrophobic forces plays a major role in the stabilization of the complex quercetin-lipoxygenase. The distance, r, between donor (lipoxygenase) and acceptor (quercetin) was calculated to be 3.84 nm based on Förster's non-radiative energy transfer theory. The results obtained from the evaluation of three dimensional florescence spectra suggest a conformational modification of the protein in the region of the coupling with quercetin.