Abstract:The interaction between quercetin and trypsin was studied by measuring the catalytic activity, the enzymatic kinetic analysis and fluorescence spectra. Quercetin showed inhibition effect on catalytic activity of trypsin. When trypsin was treated by quercetin with the molar ratio of quercetin to trypsin of 44:1 for 10mins under 37 ℃, the inhibition rate reached 32.5%. Reaction time had little effect on the inhibition rate. The type of inhibition effect was reversible competitive inhibition. Quercetin can cause the quenching of intrinsic fluorescence of trypsin in physiological condition. With fluorescence quenching method，the quenching constant Kq was found to be 4.7415×1012 (mol/L)-1?S-1 and the number of binding site N was 0.9206.
