Study on the Interaction between 3 Flavonoid Compounds and α-Amylase by Fluorescence Spectroscopy and Enzymatic Kinetics

Li, Y.; Gao, F.; Gao, F.; Shan, F.; Bian, J.; Zhao, C.

Study on the Interaction between 3 Flavonoid Compounds and α-Amylase by Fluorescence Spectroscopy and Enzymatic Kinetics

2009

The interaction between α-amylase and 3 flavonoid compounds from tartary buckwheat bran, namely, quercetin (Que), its monoglycoside isoquercetin (Iso), and its diglycoside rutinb (Rut), has been studied by fluorescence spectroscopy and enzymatic kinetics. The results indicate that Que, Iso, and Rut could bind with α-amylase to form a new complex, which exhibits an obvious fluorescence quenching. We deduce that such a quenching is a static quenching via nonradiation energy transfer. Results from plots and calculations show that the sequence of binding constants (KA) is Iso > Que > Rut. Calculation on thermodynamic parameters reveals that the main driving force of above-mentioned interaction is hydrophobic. Enzyme activity measurements show that all of the 3 flavonoid compounds are effective inhibitors toward α-amylase, and the inhibitory mode belongs to a competitive type. The sequence of affinity (1/Ki) is in accordance with the results of binding constants (KA) from fluorescence experiments.

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