Purification and characterization of baicalin-β-d-glucuronidase hydrolyzing baicalin to baicalein from fresh roots of Scutellaria viscidula Bge

The baicalin-β-d-glucuronidase that hydrolyzes the β-d-glucuronide bond of baicalin to form baicalein was isolated from fresh roots of Scutellaria viscidula Bge and the enzyme purified and characterized. The enzyme was purified to one band on SDS-polyacrylamide gel electrophoresis and its molecular weight was about 58.4 kDa. The optimum temperature of the baicalin-β-d-glucuronidase was 50 °C, and the optimum pH was 5.0. The baicalin-β-d-glucuronidase was stable at less than 70 °C and pH 4.0-7.0. Ca2+ and Zn2+ ions have no significant effect on enzyme activity, Mg2+ ion has a weakly positive effect and Cu2+ ion has a weakly negative effect on enzyme activity, while Fe3+ ion inhibits enzyme activity strongly.