Recently, Professor Zheng Pu’s team from the School of Bioengineering of Jiangnan University has made progress in MOF immobilization. The research result is”Immobilization of alpha-L-rhamnosidase on a magnetic metal-organic framework to effectively improve its reusability in the hydrolysis of rutin” was officially published in Bioresource Technology (IF=7.539) (https://doi.org/10.1016/j.biortech.2020.124611).
α-L-rhamnosidase (EC 18.104.22.168) is a glycoside hydrolase that can specifically hydrolyze the L-rhamnose residues at the non-reducing ends of glycosides and can be used for debittering fruit juices , The aroma enhancement of wine and the preparation of L-rhamnose, isoquercetin, and Prunin. When free enzymes hydrolyze glycosides, the enzymes cannot be recycled, resulting in higher costs. The immobilized enzyme is easy to separate and can be reused, and at the same time, it has strong tolerance to extreme environments, which can significantly reduce costs. However, the solubility of glycosides such as rutin is very low, resulting in low hydrolysis efficiency of immobilized enzymes. At the same time, it is difficult to separate immobilized enzymes from insoluble products and substrates, which reduces the utilization efficiency of immobilized enzymes, and therefore obtains high-efficiency Immobilized enzymes that hydrolyze low-solubility glycosides and can be recycled are essential.
Professor Zheng Pu’s team first screened different types of immobilized materials in order to obtain an efficient and easy-to-separate immobilized enzyme. The data shows that the enzyme immobilized on a magnetic metal organic framework (MOF) material ([email protected]
) hydrolyzes rutin The most efficient and easy to separate. Secondly, the immobilization conditions were optimized and the immobilized carrier was characterized, and the enzyme activity could reach 25.09 U/g. In order to obtain the best hydrolysis effect, the team optimized the conditions for hydrolysis of rutin by [email protected]
Under the best conditions, the conversion rate of 20 g/L rutin was 91.42%, and the production rate of isoquercetin was 12.78 g/L/h; The conversion rate of 50 g/L naringin can be as high as 99%. After the enzyme was immobilized, the Km value decreased from 6.97 mM to 3.62 mM, indicating that the immobilization of α-L-rhamnosidase on MOF material can significantly increase the affinity of the enzyme. Finally, in order to verify the reusability of [email protected]
, 20 g/L rutin was hydrolyzed 30 times under optimal conditions, and the conversion rate was still 73.6%after 30 repetitions. The results of this study show that the prepared magnetic MOF nanoparticles are effective carriers for immobilizing α-L-rhamnosidase, which provides a new immobilized enzyme material for the study of enzymatic hydrolysis of low-solubility flavonoids.
Professor Zheng Pu is the corresponding author of the paper, and Wang Deqing, a PhD student in 2018, is the first author of the paper. The above-mentioned research work was funded by the National First-Class Discipline Project of Light Industry Technology and Engineering (LITE2018-04), and the Jiangsu University Brand Professional Construction Project Funding Project.