The fluorescence emission spectra of dihydropyrimidinase.

<p>The decrease in intrinsic fluorescence of protein was measured at 334.5 nm upon excitation at 279 nm and 25°C with a spectrofluorimeter. (A) The fluorescence emission spectra of dihydropyrimidinase with dihydromyricetin of different concentrations (0–50 μM). The fluorescence intensity emission spectra of dihydropyrimidinase significantly quenched with dihydromyricetin. (B) The fluorescence emission spectra of dihydropyrimidinase with myricetin of different concentrations (0–50 μM). The fluorescence intensity emission spectra of dihydropyrimidinase significantly quenched with myricetin. (C) Fluorescence titrations of dihydromyricetin and myricetin with dihydropyrimidinase. An aliquot amount of dihydromyricetin and myricetin was individually added to the enzyme solution for each <i>K</i>_d. The <i>K</i>_d was obtained by the equation: ΔF = ΔF_max-<i>K</i>_d(ΔF/[compound]). Data points are an average of 2–3 determinations within 10% error.