Immobilization Of Feruloyl Esterases On Magnetic Nanoparticles And The Study Of The Properties Of Immobilized Enzyme

Ferulic acid esterase (EC 3.1.1.73, FAE), also known as cinnamic acid esterase, belongs a subclass of carboxylesterase (EC 3.1.1), which can hydrolyze the ester bonds between the hemicelluloses, hemicellulose and lignin. Ferulic acid can be released as a by-product from wheat bran and other plant, which has a broad application prospects in many areas of medicine and food industry.Magnetic nanomaterials (MNPs) as a kind of carrier for immobilization has many advantages, such as small size, large specific surface area, super paramagnetism and biological compatibility. And because of the free FAEs was limited in many applications, in this paper, the MNPs after modification and oxidation were used to immobilize FAEs.The Fe3O4 and Fe2O3 magnetic nanomaterials were prepared, then were used to immobilize FAEs after characterization. At first, the optimal conditions for the immobilization were studied, and the optimal immobilization conditions of Fe3O4 observed were enzyme 0.2 mg (1 mg/mL,0.2 mL), magnetic Fe3O4 nanoparticles 4 mg,45℃, pH 6.0, immobilization time 3 h, while most of the optimal conditions of Fe2O3 were same as Fe3O4, except that the temperature is 25℃. Furthermore, the properties of the two immobilized enzyme activity for comparison were explored. We found that the heat resistance and pH tolerance of FAEs after immobilization were improved, and the repeated application of Fe3O4 immobilized enzyme was higher than Fe2O3 immobilized enzyme.The Fe3O4 magnetic nanomaterials were modified by APTES and glutaraldehyde, respectively, and we found that a concentration of 6% glutaraldehyde was the optimal value. The materials after modification were used to characterize and immobilize FAEs. The results showed that the capacity of Fe3O4-CHO immobilized enzyme was stronger. When add the same quality of the immobilized enzyme, the activity of Fe3O4-CHO immobilized enzyme was twice the performance of the immobilized enzyme by Fe3O4-NH2. The Fe3O4-CHO immobilized enzyme also exhibited super operational stability, after continuous application of six,the immobilized enzyme still showed 67% remaining activity, and Fe3O4-NH2 immobilized enzymes only showed 38%.At last, we used the four materials Fe3O4, Fe2O3, Fe3O4-NH2 and Fe3O4-CHO to immobilize FAEs, and the immobilized enzyme as the catalyst to simulate the industrial production of ferulic acid. The results showed that the ability to release ferulic acid from the destarched wheat bran of immobilized enzyme was not as good as free FAEs, and the largest ferulic acid release rate was 11.25%,8.4%,11.7% and 11.4%, respectively, while ferulic acid release rate of the free enzyme was 12.38%. And the Fe3O4-NH2 immobilized enzyme showed the strongest capacity to decompose the destarched wheat bran, which provides a reference for future industrial production.