Abstract：
Aspergillus oryzae β-D-galactosidase (β-Gal) efficiently hydrolyzes sesaminol triglucoside into sesaminol, which has higher biological activity. However, β-Gal is difficult to be separate from the reaction mixture and limited by stability. To resolve these problems, β-Gal was immobilized on amino-functionalized magnetic nanoparticles mesoporous silica pre-activated with glutaraldehyde (Fe3O4@mSiO2-β-Gal), which was used for the first time to prepare sesaminol. Under the optimal conditions, the immobilization yield and recovered activity of β-Gal were 57.9 ± 0.3 % and 46.5 ± 0.9 %, and the enzymatic loading was 843 ± 21 Uenzyme/gsupport. The construction of Fe3O4@mSiO2-β-Gal was confirmed by various characterization methods, and the results indicated it was suitable for heterogeneous enzyme-catalyzed reactions. Fe3O4@mSiO2-β-Gal was readily separable under magnetic action and displayed improved activity in extreme pH and temperature conditions. After 45 days of storage at 4 °C, the activity of Fe3O4@mSiO2-β-Gal remained at 92.3 ± 2.8 %, which was 1.29 times than that of free enzyme, and its activity remained above 85 % after 10 cycles. Fe3O4@mSiO2-β-Gal displayed higher affinity and catalytic efficiency. The half-life was 1.41 longer than free enzymes at 55.0 °C. Fe3O4@mSiO2-β-Gal was employed as a catalyst to prepare sesaminol, achieving a 96.7 % conversion yield of sesaminol. The excellent stability and catalytic efficiency provide broad benefits and potential for biocatalytic industry applications.
摘要：
米曲霉β-D-半乳糖苷酶(β-Gal)能有效地将芝麻酚三葡萄糖苷水解为芝麻酚,具有较高的生物活性。然而,β-Gal难以从反应混合物中分离并且受到稳定性的限制。为了解决这些问题,将β-Gal固定在戊二醛预活化的氨基功能化磁性纳米颗粒介孔二氧化硅（Fe3O4@mSiO2-β-Gal）上，首次用于制备芝麻酚。在最优条件下,β-Gal的固定化产率和回收活性分别为57.9±0.3％和46.5±0.9％，酶载量为843±21酶/gsupport。通过各种表征方法证实了Fe3O4@mSiO2-β-Gal的构建,结果表明，它适用于非均相酶催化反应。Fe3O4@mSiO2-β-Gal在磁作用下易于分离，并在极端pH和温度条件下显示出改善的活性。在4°C下储存45天后，Fe3O4@mSiO2-β-Gal的活性保持在92.3±2.8%，是游离酶的1.29倍，10个周期后其活性保持在85%以上。Fe3O4@mSiO2-β-Gal表现出更高的亲和力和催化效率。在55.0°C时，半衰期比游离酶长1.41。以Fe3O4@mSiO2-β-Gal为催化剂制备芝麻酚,芝麻酚的转化率为96.7%。优异的稳定性和催化效率为生物催化工业应用提供了广泛的益处和潜力。
