Purification and characterization of a highly selective glycyrrhizin-hydrolyzing β-glucuronidase from Penicillium purpurogenum Li-3

► A novel β-glucuronidase from fungus Penicillium purpurogenum was purified. ► The purified β-glucuronidase was characterized. ► Mg2+ enhances enzymatic activity, but Mn2+, Zn2+ and Cu2+ inhibit activity. ► The enzyme converts glycyrrhizin directly to glycyrrhetic acid mono-glucuronide.