Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: Glycyrrhetinic acid 3-O-mono-b-D-glucuronide (GAMG), an important pharmaceutical intermediate and functional sweetener, has broad applications in the food and medical industries. A green and cost-effective method for its preparation is highly desired. Using sitedirected mutagenesis, we previously obtained a variant of β-glucuronidase from Aspergillus oryzae Li-3 (PGUS1), which can specifically transform glycyrrhizin (GL) into GAMG. In this study, a facile method was established to prepare a CaHPO 4 -PGUS1 hybrid nanoflower for enzyme immobilization, based on protein-inorganic hybrid selfassembly. Under optimal conditions, 1.2 mg of a CaHPO 4 -PGUS1 hybrid nanoflower precipitate with 71.2% immobilization efficiency, 35.60 mg$g -1 loading capacity, and 118% relative activity was obtained. Confocal laser scanning microscope and scanning electron microscope results showed that the enzyme was encapsulated in the CaHPO 4 -PGUS1 hybrid nanoflower. Moreover, the thermostability of the CaHPO 4 -PGUS1 hybrid nanoflower at 55°C was improved, and its half-life increased by 1.3 folds. Additionally, the CaHPO 4 -PGUS1 hybrid nanoflower was used for the preparation of GAMG through GL hydrolysis, with the conversion rate of 92% in 8 h, and after eight consecutive runs, it had 60% of its original activity.

Construction of a CaHPO 4 -PGUS1 hybrid nanoflower through protein-inorganic self-assembly, and its application in glycyrrhetinic acid 3-O-mono-β-D-glucuronide preparation