Study of fluorescence quenching mechanism between quercetin and tyrosine-H2O2-enzyme catalyzed product

摘要

Because of catalysis of horseradish peroxidase, the tyrosine reacted with H-2 O-2 to form the product S which was a strong fluorescence substance. To the product S, the quercetin was acted as a quencher. The fluorescence quenching mechanism was studied by the measurement of fluorescence lifetime and based on the Stern-Volmer plot. The reaction mechanism, which was the static quenching process between quercetin and product S, was studied. The binding constant, K= 4.03 x 10(5) L mol(-1) and the number of binding sites n = 1.09, were obtained against this reaction. The thermodynamic parameters Were estimated. The data, Delta H= -75.68 kJ mol(-1), Delta S= -147.9j K-1 mol(-1) and Delta G = -29.17 kJ mol(-1) showed that the reaction was spontaneous and exothermic. What is More, both Delta H and Delta S were negative values indicated that van der Waals interaction and hydrogen bonding were the predominant intermolecular forces between quercetin and product S. (c) 2008 Elsevier B.V. All rights reserved