Abstract: A rutin-hydrolysis enzyme (RHE) was isolated from Fagopyrum tataricum (tartary buckwheat) seeds by extraction with 20 mmol/L acetate buffer acetate buffer, ammonium acetate fractionation, anion exchange chromatography and size exclusion chromatography. The molecular weight of RHE, as determined by SDS-PAGE, was 70 kD. The optimum hydrolysis pH was 5.0. The activity was not inhibited by an ethanol concentration of 20% in the reaction system, but an inhibitory rate above 90% was observed when ethanol concentration was higher than 50%. Fluorescence spectroscopic analysis indicated that Cu2+ could be bound to RHE at a molar ratio of 1:1 to generate a stable complex without fluorescence. Meanwhile, Cu2+ revealed an obvious inhibitory effect on the activity of RHE. These investigations provided a theoretical basis for future enzymatic preparation of quercetin.

Key words: tartary buckwheat, quercetin, rutin-hydrolysis enzyme, fluorescence spectrum