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Immobilization of

Xiaokai SONG,Zhongyi JIANG,Lin LI,Hong WU

《化学科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 353-361 doi: 10.1007/s11705-014-1421-2

摘要： Mesoporous silica particles were prepared for efficient immobilization of the -glucuronidase (GUS) through a biomimetic mineralization process, in which the solution containing lysozyme and GUS were added into the prehydrolyzed tetraethoxysilane (TEOS) solution. The silica particles were formed in a way of biomineralization under the catalysis of lysozyme and GUS was immobilized into the silica particles simultaneously during the precipitation process. The average diameter of the silica particles is about 200 nm with a pore size of about 4 nm. All the enzyme molecules are tightly entrapped inside the biosilica nanoparticles without any leaching even under a high ionic strength condition. The immobilized GUS exhibits significantly higher thermal and pH stability as well as the storage and recycling stability compared with GUS in free form. No loss in the enzyme activity of the immobilized GUS was found after 30-day’s storage, and the initial activity could be well retained after 12 repeated cycles.

关键词： storage and recycling stability     silica nanoparticles     biocatalysis     biomimetic synthesis     β-glucuronidase encapsulation    

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Enhanced production of

Shen Huang,Xudong Feng,Chun Li

《化学科学与工程前沿（英文）》 2015年 第9卷 第4期   页码 501-510 doi: 10.1007/s11705-015-1544-0

摘要： -Glucuronidase from Li-3 (PGUS) can efficiently hydrolyze glycyrrhizin into the more valuable glycyrrhetic acid monoglucuronide. However, a low productivity of PGUS and the lack of an effective separation strategy have significantly limited its industrial applications. Therefore, the production of PGUS has been improved by optimizing both the fermentation and purification strategies. A two-stage fermentation strategy was developed where PGUS was first grown with glucose and then PGUS was produced in the presence of glycyrrhizin as an inducer. By using this strategy, the biomass was increased 1.5 times and the PGUS activity increased 5.4 times compared to that when glycyrrhizin was used as the sole carbon source. The amount of PGUS produced was increased another 16.6% when the fermentation was expanded to a 15-L fermenter. An effective protocol was also established to purify the PGUS using a sequential combination of hydrophobic, strong anion-exchange and gel filtration chromatography. This protocol had a recovery yield of 6% and gave PGUS that was 39 times purer than the crude PGUS. The purified PGUS had a specific activity of 350 U·mg .

关键词： β-glucuronidase     glycyrrhetic acid monoglucuronide     cell disruption     purification     chromatography    

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Construction of a CaHPO4-PGUS1 hybrid nanoflower through protein-inorganic self-assembly, and its application in glycyrrhetinic acid 3-O-mono-β-D-glucuronide preparation

Tian Jiang, Yuhui Hou, Tengjiang Zhang, Xudong Feng, Chun Li

《化学科学与工程前沿（英文）》 2019年 第13卷 第3期   页码 554-562 doi: 10.1007/s11705-019-1834-z

摘要： Glycyrrhetinic acid 3- -mono- -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 site-directed mutagenesis, we previously obtained a variant of -glucuronidase from Li-3 (PGUS1), which can specifically transform glycyrrhizin (GL) into GAMG. In this study, a facile method was established to prepare a CaHPO -PGUS1 hybrid nanoflower for enzyme immobilization, based on protein-inorganic hybrid self-assembly. Under optimal conditions, 1.2 mg of a CaHPO -PGUS1 hybrid nanoflower precipitate with 71.2% immobilization efficiency, 35.60 mg∙g 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 -PGUS1 hybrid nanoflower. Moreover, the thermostability of the CaHPO -PGUS1 hybrid nanoflower at 55°C was improved, and its half-life increased by 1.3 folds. Additionally, the CaHPO -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.

关键词： β-glucuronidase     enzyme-inorganic hybrid nanoflower     biotransformation     glycyrrhizin     glycyrrtinic acid 3-O-mono-β-D-glucuronide    

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标题 作者 时间 类型 操作

Immobilization of

Xiaokai SONG,Zhongyi JIANG,Lin LI,Hong WU

期刊论文

Enhanced production of

Shen Huang,Xudong Feng,Chun Li

期刊论文

Construction of a CaHPO4-PGUS1 hybrid nanoflower through protein-inorganic self-assembly, and its application in glycyrrhetinic acid 3-O-mono-β-D-glucuronide preparation

Tian Jiang, Yuhui Hou, Tengjiang Zhang, Xudong Feng, Chun Li

期刊论文